The Straight Dope

Go Back   Straight Dope Message Board > Main > General Questions

Reply
 
Thread Tools Display Modes
  #1  
Old 07-29-2010, 10:12 PM
Markxxx Markxxx is offline
BANNED
 
Join Date: Apr 1999
Location: Chicago,IL
Posts: 14,962
Changing An Electrical Outlet Without Turning The Power Off

I recently had an outlet blow and my landlord came in, turned off the breakers and replaced the outlet in about five minutes. I didn't realize it was so easy to do.

Anyway I was talking to a mechanic at a factory where I have a temp job and he said, "Yeah, well you don't have to turn off the power to replace an outlet if you know what you're doing."

I said, I didn't buy it.

He said, it was simply a matter of knowning what wires to change in what order, so you don't shock yourself.

First of all is this even possible for true?

Second, why would anyone do this? Why WOULDN'T YOU turn off the breakers or pull the fuses?

And of course I would never advocate doing this if it was possible
Reply With Quote
Advertisements  
  #2  
Old 07-29-2010, 10:16 PM
beowulff beowulff is offline
Member
 
Join Date: May 2001
Location: Scottsdale, more-or-less
Posts: 10,670
Sure it can be done.
You just need to use insulated tools, and be careful not to short Hot to Ground.
I don’t think I would do it, if I had a choice, though.
Reply With Quote
  #3  
Old 07-29-2010, 10:18 PM
TheBori TheBori is offline
Guest
 
Join Date: May 2000
I've done it. Just too lazy to go out to the garage and turn off the breaker..especially if it's going to kill the lights in the room. No big deal, it's only 110v. If you only touch one wire at a time you don't get shocked. If you get bit, it's only a tingle. Now, 220v (for our European friends) will take you off a ladder.
Electricity is a very logical thing to work with...if you understand it, you can work with it safely.

Now go stick a fork in there and see what it feels like.
Reply With Quote
  #4  
Old 07-29-2010, 10:19 PM
pulykamell pulykamell is online now
Charter Member
 
Join Date: May 2000
Location: SW Side, Chicago
Posts: 30,197
Yes, it is possible. My brother and I wired several outlets in my parents house in this manner. Why? I can't remember. My brother was used to wiring circuits hot, so we did so. Perhaps we were just lazy. I did get a brief shock once, but it's really not that hard to do. Advisable? No. Stupid? Probably. Possible? Of course.
Reply With Quote
  #5  
Old 07-29-2010, 10:20 PM
Leaffan Leaffan is online now
Member
 
Join Date: Aug 2005
Location: Ottawa Valley, eh.
Posts: 16,043
You would not feel a thing if you were touching only the hot wire, and were isolated from ground.

Yes, it is not only possible, but even a lot of electricity providers have men in elevated "buckets" working on high voltage lines with no fear of electrical shock. Electricity needs a path back to ground. If one isn't available then no hazard exists. Take a look at birds perched on 10 gazillion volt lines.
Reply With Quote
  #6  
Old 07-29-2010, 10:47 PM
aceplace57 aceplace57 is offline
Guest
 
Join Date: Oct 2009
I turn off the breaker.

I know several electricians that prefer working live. It forces them to always work carefully and respect the voltage. That way they never assume a line is dead and touch both wires.

They make a good point. Those beeping circuit testers sometimes give false readings if there isn't a good ground or the batterys are low.

Mike Holmes uses one of these no contact testers on every episode of Holmes on Homes. Hold it near a wire and it beeps if its hot. Most of the time they are accurate. One false reading could lull you into grabing hot wires.
http://www.amazon.com/Fluke-1AC-A1-I...ef=pd_sim_hi_7

Last edited by aceplace57; 07-29-2010 at 10:48 PM..
Reply With Quote
  #7  
Old 07-29-2010, 10:48 PM
johnpost johnpost is online now
Guest
 
Join Date: Jul 2009
yes it is possible.

you can still get a shock when only touching the live hot and think you are isolated from ground. your clothes, shoes, surface ladder all can provide a path even though you think they are nonconducting, all depends on what is there at the moment.

to do work on live circuits depends on the nature of the circuit if it can be done safely. it also takes lots of experience and a sharp focus to do so safely. an energized wire looks the same
as an unenergized wire and it only takes half a second lapse of thought to do the wrong thing for that circumstance. for the safety of people and equipment i would walk a bit to shut off the circuit.

utility linemen do work live thought they have lots of training and expensive high quality protective equipment and tools and specific procedures.
Reply With Quote
  #8  
Old 07-29-2010, 10:51 PM
johnpost johnpost is online now
Guest
 
Join Date: Jul 2009
Quote:
Originally Posted by aceplace57 View Post
Mike Holmes uses one of these no contact testers on every episode of Holmes on Homes. Hold it near a wire and it beeps if its hot. Most of the time they are accurate. One false reading could lull you into grabing hot wires.
a careful electrician knows their test equipment works correctly before trusting it during work.
Reply With Quote
  #9  
Old 07-29-2010, 10:55 PM
johnpost johnpost is online now
Guest
 
Join Date: Jul 2009
Quote:
Originally Posted by aceplace57 View Post
I know several electricians that prefer working live. It forces them to always work carefully and respect the voltage. That way they never assume a line is dead and touch both wires.

They make a good point.
that assumption is a good one if you know the circuit is live or not unless you can lockout the circuit (like you might in an industrial or commercial installation).
Reply With Quote
  #10  
Old 07-29-2010, 11:00 PM
Joey P Joey P is online now
Charter Member
 
Join Date: Jun 1999
Location: Milwaukee, WI
Posts: 21,104
I've done it live...I usually avoid it, been shocked one to many times. As careful as I am, it's to easy for a hand to slip, or a wire to move or a screwdriver to slide towards your thumb or any number of other things. A 120V shock is more startling then painful, but it's not something I would do on purpose.

BTW, I've got one of those contactless voltage detectors. They're nice and all, but I would never assume the power is out just because it didn't beep. I've got a handful of these that I always have nearby when I'm doing electrical work. The only time I've gotten a false negative with this type was when I was working out in the sun and couldn't see the light.
Reply With Quote
  #11  
Old 07-29-2010, 11:14 PM
boytyperanma boytyperanma is offline
Guest
 
Join Date: Dec 2005
Quote:
Originally Posted by johnpost View Post
Quote:
Originally Posted by aceplace57 View Post
Mike Holmes uses one of these no contact testers on every episode of Holmes on Homes. Hold it near a wire and it beeps if its hot. Most of the time they are accurate. One false reading could lull you into grabing hot wires.
a careful electrician knows their test equipment works correctly before trusting it during work.
I'm a reasonable careful electrician and know to never trust those no contact testers. Every electrician I know or have worked with uses a volt meter for testing wires before handling them. I carry a volt meter on any given job. I have a non-contact test and a multi-meter the non-contact rarely leaves my bag. The multi- meter can do voltage as well but I'm not going to trust my life to a digital meter.

Changing switches and outlets is somewhere I will cut corners on. By code you are supposed to turn off and tag the breaker for any branch circuit work. Walking in for a short service call however it can easily take ten times as long to find the correct breaker as it would to just change the device. It can also be a nuisance to the people in the building if you have to flip through breakers to find the right one.

Someone familiar with electrical work can easily change an outlet life without any ill effect. It is simply safer to do so with the power off.

It is akin to walking around barefoot. If you know where your walking you can avoid stepping on anything sharp. If you are in unfamiliar territory putting on a pair of shoes is a really good idea so you don't find that random shard of glass.
Reply With Quote
  #12  
Old 07-29-2010, 11:35 PM
Rick Rick is offline
Charter Member
 
Join Date: Aug 1999
Posts: 15,493
You can turn off the breaker and still get one hell of a shock. Happened to me.
Here is my story.
It was summer, I was going to change the outlet behind my stove. I usually change outlets and switches hot. (yes I know it is a dumb idea, but it is me, I have lots of experience yada, yada, yada) Anyway this day my loving wife says "I wish you would turn off the power"
So to please her I plugged in a lamp turned it on, went to the panel, flipped the breaker and verified that the light was off.
so I pull the stove out, and am standing behind it leaning against my new gas stove, and since it is summer, and it hotter than hell I am sweating a goodly bit. As in my shirt is soaked.
So I open up the box. Unscrew the hot grab it with my hand and move it over to the new outlet and screw it on, no problem.
On the neutral side there are two wires, one comes in the bottom of the box, and the other comes in the top. I unscrew the lower wire and move it to the new outlet. I unscrew the top wire and grab it, and get the mother loving shock of my life. It traveled up my right arm, around my rib cage and out my back where it was leaning against my new gas stove. I say gas, because gas pipes are buried in the ground and are well umm grounded.
It turns out that I got shocked by a shared neutral. That wire that went out the top of that outlet went to the light on the ceiling that was on another circuit. When I disconnected the lower wire I broke the ground connection, and that upper wire became live with 120V looking for a ground. It found one though my body.
I hate shared neutrals.
When I rewired my garage (large sub panel, 7 different circuits, both 220, and 110) I did it dead, and when I was done, then I turned on the power. Oh, and there is not a single shared neutral in the garage. I don't care that I had to buy some extra wire, there aren't any.
bottom line is, just because one hot wire in a box is dead that does not mean that every wire in that box is dead. If you assume they are all dead, then you could get a shocking surprise. If you assume they are all hot then you won't go grab one by mistake.
But as they say, YMMV, do as I say don't do as I do, always follow all safety regulations, do not taunt the happy fun ball.

ETA I have never been shocked working hot on an outlet.

Last edited by Rick; 07-29-2010 at 11:38 PM..
Reply With Quote
  #13  
Old 07-29-2010, 11:58 PM
Sam Stone Sam Stone is offline
Charter Member
 
Join Date: Jun 1999
Posts: 25,508
A good electrician will shut off the breaker, test to make sure that the power is off, and then STILL treat the wires as if they are hot.

I think of it like handling a gun. If you hand me a gun and tell me it's unloaded, I'm still going to check. And even after I check, I'm still going to handle it as if was loaded. Too many people have been hurt or killed because they gradually get sloppier with dangerous things, until finally a weird cooincidence or mental lapse or a distraction kills them. This is why pilots don't skip checklist items even if they are certain that they don't need to do them; it's the routine that keeps them alive when the odds line up against them.
Reply With Quote
  #14  
Old 07-30-2010, 03:53 AM
Markxxx Markxxx is offline
BANNED
 
Join Date: Apr 1999
Location: Chicago,IL
Posts: 14,962
Thanks for the replies, it's interesting to know.

I still don't see why you'd not turn the electricity off. Yeah I know it's that you get complacent and such.

To me I will try anything like plumbing, painting, drywall etc, but I REFUSE to go anywhere near electricity. I do understand the pricinciples behind it, I just feel electricity is out to get me
Reply With Quote
  #15  
Old 07-30-2010, 04:31 AM
Superhal Superhal is offline
Suspended
 
Join Date: Sep 2009
Posts: 6,376
I did it once when I was like 12 years old. It was the only triple prong outlet in the house outside of the kitchen. Of course, it wasn't grounded (it just had three prongs.) I didn't get shocked. Years later, I decided to ground it. I blew the breaker and saw some nice sparks when I tried to connect the ground wire to a water pipe. The sparking convinced me to call an electrician. He came in, said I did it right, and charged me $50.
Reply With Quote
  #16  
Old 07-30-2010, 06:45 AM
Harmonious Discord Harmonious Discord is offline
Guest
 
Join Date: Apr 1999
The answer is you can change it live and live, but you could also die. Leave the Darwin awards to other people.
Reply With Quote
  #17  
Old 07-30-2010, 06:53 AM
rbroome rbroome is offline
Member
 
Join Date: Jun 2003
Location: Louisiana
Posts: 1,851
Quote:
Originally Posted by Markxxx View Post
I recently had an outlet blow and my landlord came in, turned off the breakers and replaced the outlet in about five minutes. I didn't realize it was so easy to do.

Anyway I was talking to a mechanic at a factory where I have a temp job and he said, "Yeah, well you don't have to turn off the power to replace an outlet if you know what you're doing."

I said, I didn't buy it.

He said, it was simply a matter of knowning what wires to change in what order, so you don't shock yourself.

First of all is this even possible for true?

Second, why would anyone do this? Why WOULDN'T YOU turn off the breakers or pull the fuses?

And of course I would never advocate doing this if it was possible
happens all the time. electricians don't bother to take the time to find and turn off the breaker. Most of the time they avoid a shock. The other times, I am told one gets used to it. I hate the feeling and always turn off the breaker, but many electricians don't. (I am not an electrician BTW, just a homeowner with some experience in wiring)
Reply With Quote
  #18  
Old 07-30-2010, 07:33 AM
Keeve Keeve is offline
Guest
 
Join Date: Aug 2000
Quote:
Originally Posted by Markxxx View Post
I still don't see why you'd not turn the electricity off.
Suppose some other device is on that same circuit, and you have a good reason why you don't want to turn it off. For instance, suppose that if you turn the lights out, you won't have enough light to change the outlet, but all the lights are on the same circuit as the outlet is. Catch 22 -- it is dangerous to change the outlet if you leave the power on, but it is impossible to change the outlet if you turn the power off. One solution is to get a good flashlight, but that might not be easy. So instead, leave the power on, and be very careful.
Reply With Quote
  #19  
Old 07-30-2010, 07:36 AM
boytyperanma boytyperanma is offline
Guest
 
Join Date: Dec 2005
Quote:
Originally Posted by rbroome View Post
Happens all the time. electricians don't bother to take the time to find and turn off the breaker. Most of the time they avoid a shock. The other times, I am told one gets used to it. I hate the feeling and always turn off the breaker, but many electricians don't. (I am not an electrician BTW, just a homeowner with some experience in wiring)
Any electrician that claims 'they get used to it' needs to be told to get the hell out. That's incredibly stupid. Even 120volt can kill you instantly, it's not like they get some special immunity for getting hit in the past. Their luck has just been good so far.

I've probably been shocked less then 5 times. I've never shocked across my body, only been hit on a singly hand.

I've blown up a number of good tools. I'll take chances with a screw driver or a pair of cutters. Though I'll admit you feel like a total moron when you turn a 40 dollar pair of linesmans to slag.
Reply With Quote
  #20  
Old 07-30-2010, 07:51 AM
JFLuvly JFLuvly is offline
Guest
 
Join Date: Dec 2008
Quote:
Though I'll admit you feel like a total moron when you turn a 40 dollar pair of linesmans to slag
My Kleins' have three holes in the cutters.

As far working on live circuits goes I would ask my friend, he was an electrician....key word being was....he's dead now!
Reply With Quote
  #21  
Old 07-30-2010, 08:11 AM
Joey P Joey P is online now
Charter Member
 
Join Date: Jun 1999
Location: Milwaukee, WI
Posts: 21,104
[QUOTE=Keeve;12744939]
Quote:
Originally Posted by Markxxx View Post
it is dangerous to change the outlet if you leave the power on, but it is impossible to change the outlet if you turn the power off. One solution is to get a good flashlight, but that might not be easy. So instead, leave the power on, and be very careful.
There was a Handy Manny episode about exactly that. They ended up using a bunch of mirrors to reflect light from the kitchen on to the work area.
Reply With Quote
  #22  
Old 07-30-2010, 08:35 AM
alice_in_wonderland alice_in_wonderland is offline
Guest
 
Join Date: Mar 2001
Quote:
Originally Posted by Keeve View Post
Catch 22 -- it is dangerous to change the outlet if you leave the power on, but it is impossible to change the outlet if you turn the power off.
Uh, no. A 'good flashlight' is a standard piece of equipment in an electrician's kit. The Mr. only does commercial and industrial jobs at work, but when he's putzing around the house he still turns off the breakers.

Honestly, it's pretty lazy not to, as well as being rather dumb.
Reply With Quote
  #23  
Old 07-30-2010, 09:14 AM
Claude Remains Claude Remains is offline
Guest
 
Join Date: Oct 2004
Do it all the time. This is the SDMB, and still I like to see that not everyone is a "know it all".-DO NOT PLAY WITH ELECTRICITY- And yes I have been zapped by 110 and 220. I used to work with 440 at the water plant but thank og we had to work in pairs to keep it (me) safe.
Reply With Quote
  #24  
Old 07-30-2010, 09:44 AM
The Great Sun Jester The Great Sun Jester is offline
Guest
 
Join Date: Mar 2004
Pretty much the only time I find myself replacing a wall outlet is in a 40+ year old house and I'm coming behind 3 or 4 other DIY geniuses. Many times I've come across what appears to be a simple 4-plug outlet the is actually a confluence of two separate circuits, sometimes sharing a common ground or negative. Other times I'v seen the white wire hot and the black negative. Out of habit I simply distrust anyone else's work and check every wire in a box and proceed accordingly, and it's just easier to leave the power on and be careful than to run out to the box, flip breakers until your lamp or radio in the subject outlet turns off, and then tear into the project only to discover there's another HOT circuit in the there waiting like a viper.

Balls. Leave it hot, know it's all hot, use one hand whenever possible and pay attention to what you're doing.
Reply With Quote
  #25  
Old 07-30-2010, 09:57 AM
johnpost johnpost is online now
Guest
 
Join Date: Jul 2009
when electricians have to work on live circuits in industrial and commercial settings they work in pairs for safety as mentioned. a good safety procedure is that they frequently look to each other (in a safe manner with themself not near any wires) to see the other guy is still breathing and yell a reminder that the circuit is still live to each other in order to help prevent that half a second lapse in thought that could kill you.
Reply With Quote
  #26  
Old 07-30-2010, 10:28 AM
billfish678 billfish678 is offline
Guest
 
Join Date: Jun 2006
Its doable sure.

As for working on a live line to keep you safe because you'll be more carefull...well, I think thats macho BS IMO.

I turn off the power and STILL assume its live when working on it. Thats the safest way to do it.
Reply With Quote
  #27  
Old 07-30-2010, 10:32 AM
CookingWithGas CookingWithGas is offline
Charter Member
 
Join Date: Mar 1999
Location: Tysons Corner, VA, USA
Posts: 9,659
Quote:
Originally Posted by Rick View Post
It turns out that I got shocked by a shared neutral. That wire that went out the top of that outlet went to the light on the ceiling that was on another circuit. When I disconnected the lower wire I broke the ground connection, and that upper wire became live with 120V looking for a ground. It found one though my body.
I hate shared neutrals.
IANAE but I have never run across a shared neutral. Does that conform to code?
Reply With Quote
  #28  
Old 07-30-2010, 10:58 AM
Claude Remains Claude Remains is offline
Guest
 
Join Date: Oct 2004
This is why you should never flip breaker switches till the unit you are gonna work on is "off". If you are not sure of what you are doing, please shut off the entire home at the main.
Reply With Quote
  #29  
Old 07-30-2010, 11:13 AM
Hari Seldon Hari Seldon is offline
Guest
 
Join Date: Mar 2002
Quote:
Originally Posted by Inigo Montoya View Post
Pretty much the only time I find myself replacing a wall outlet is in a 40+ year old house and I'm coming behind 3 or 4 other DIY geniuses. Many times I've come across what appears to be a simple 4-plug outlet the is actually a confluence of two separate circuits, sometimes sharing a common ground or negative. Other times I'v seen the white wire hot and the black negative. Out of habit I simply distrust anyone else's work and check every wire in a box and proceed accordingly, and it's just easier to leave the power on and be careful than to run out to the box, flip breakers until your lamp or radio in the subject outlet turns off, and then tear into the project only to discover there's another HOT circuit in the there waiting like a viper.

Balls. Leave it hot, know it's all hot, use one hand whenever possible and pay attention to what you're doing.
Every two outlet circuit in my kitchen (there are three of them) is wired to two separate circuits (the same two). The electrician who did this said the code required it. The reason he gave was that in a kitchen you might be tempted to plug in a toaster in the top and a coffee maker in the bottom and that would exceed the 15 amps of one circuit. Of course, there is no reason I couldn't plug the toaster into the top of one of the outlets and the coffee maker into the top of a different one, with the same effect. Nonetheless the point above is well taken. Unless you have tested every outlet, don't assume that if one is off, so is the other.

I suppose I could replace a live outlet, but I'll be damned if I would try.
Reply With Quote
  #30  
Old 07-30-2010, 11:21 AM
Chronos Chronos is offline
Charter Member
 
Join Date: Jan 2000
Location: The Land of Cleves
Posts: 54,072
Back when I worked for an electrician, the rule was to always have three layers of safety, such that if any two of them failed, you'd still be OK. Turning off the power at the breaker is one of the easier things you can do in this regard. Yes, it can turn out, for various reasons, that that doesn't work: That's why you have the other two layers of safety.
Reply With Quote
  #31  
Old 07-30-2010, 11:33 AM
engineer_comp_geek engineer_comp_geek is offline
Robot Mod in Beta Testing
Moderator
 
Join Date: Mar 2001
Location: Pennsylvania
Posts: 8,214
I personally shut off the breaker and then treat the wires as if they were hot anyway.

At work I occasionally deal with hot circuits. It's not that bad if you just keep safe and think about what you are doing. 110 and 220 don't bother me, but when I'm near 440 and above I really start consciously thinking more about safety.

Quote:
Originally Posted by boytyperanma View Post
Any electrician that claims 'they get used to it' needs to be told to get the hell out. That's incredibly stupid.
I agree with that. If you can feel the shock, it's already got more than enough current flowing to potentially stop your heart. It's not that hard to avoid getting shocked. Anyone who just thinks getting shocked is no big deal and doesn't take the proper precautions is just stupid.

I personally have only been shocked twice in my life. Once when I was about six years old I plugged in a record player with my fingers on each prong of the plug. The second time was at work. I was working on a prototype of an industrial controller and the machine was off but was still plugged in. I reached inside to fiddle with something and happened to contact some power filtering circuitry that I thought was switched off when the power switch was off. It wasn't.

Quote:
Originally Posted by Superhal View Post
Years later, I decided to ground it. I blew the breaker and saw some nice sparks when I tried to connect the ground wire to a water pipe. The sparking convinced me to call an electrician. He came in, said I did it right, and charged me $50.
For the benefit of anyone coming into this thread, you never, ever, want to use your water pipe as a ground. It used to be that you were required to ground the house through the cold water pipe. That was changed many years ago and now a separate ground is required. A lot of folks back then used to use water pipes as their ground, but what you really want to do is keep your protective grounds from your circuits completely separate from your water pipes. However, you also want to ground all of your metal water pipes for safety.

You want your water pipes grounded, but you don't want to use the water pipes as grounds for anything else.
Reply With Quote
  #32  
Old 07-30-2010, 11:47 AM
Magiver Magiver is offline
Guest
 
Join Date: Apr 2003
If there is substantial length to the wire and the outlet has spade connectors then it's doable to replace it safely. I always screw the wires in the side terminals so that would greatly increase the danger.

The one time I did an installation with live wires involved a color coding issue so I needed the power on to establish what was actually live. Since all the wires were away from a grounded box I was able to spread them out and cover each wire while working on the others. I would certainly never recommend doing it and in retrospect should have turned the power off when I was able to identify the wires but it was hot in the attic and I got lazy.
Reply With Quote
  #33  
Old 07-30-2010, 11:47 AM
dmatsch dmatsch is offline
Guest
 
Join Date: Mar 2006
Quote:
Originally Posted by TheBori View Post
I've done it. Just too lazy to go out to the garage and turn off the breaker..especially if it's going to kill the lights in the room. No big deal, it's only 110v. If you only touch one wire at a time you don't get shocked. If you get bit, it's only a tingle. Now, 220v (for our European friends) will take you off a ladder.
Electricity is a very logical thing to work with...if you understand it, you can work with it safely.

Now go stick a fork in there and see what it feels like.
I was an electronics engineer in the Air Force, so I know how it feels to get bit by 110 (5000v, 15,000v). It's the amperage. 1/4 of a volt will kill you if it's > .01 amp.

"Bites" were taken very seriously, and weren't as trivial as you put it above. Anyone who gets bitten proceeds immediately to the infirmary where they were hooked up to heart monitors for an hour.

Any one with a congenital heart defect can find themselves very dead where others would simply go "ouch" and move along (granted a little wobbly).

That being said, why take a chance. Turn off the freakin' breaker.

Last edited by dmatsch; 07-30-2010 at 11:48 AM..
Reply With Quote
  #34  
Old 07-30-2010, 11:49 AM
Dallas Jones Dallas Jones is offline
Guest
 
Join Date: Apr 2008
The industiral electrician who used to do the work at a plant I worked for had a little device about the size of a pen that could tell if current was flowing through a wire.

I said, "That's neat! What do you call it"

He said, we call them liars.
Reply With Quote
  #35  
Old 07-30-2010, 11:52 AM
kunilou kunilou is online now
Charter Member
 
Join Date: Apr 1999
Posts: 17,362
It's a lot like jumping a car battery: start with wire A and terminal 1, then wire A and terminal 2, then wire B, etc. People jump start cars all the time with no problem. Of course, people also create sparks while jumping cars, brush one of the cables across a grounded section of the frame, accidentally connect the red thingy to the black thingy, etc. As the manual says "unpredictable results may occur."

Every outlet box I've ever had the unpleasure to work on has had a bunch of stiff wires stuffed into a small space. Sometimes the screw terminals on the old outlet don't want to be unscrewed. Sometimes the wires slip off the terminals while you're trying to screw them down. Sometimes you touch two things together that should be kept apart.

Unpredictable results may occur. Sure, maybe you can do it, but why the hell would you want to do it? Just go downstairs and throw the breaker.
Reply With Quote
  #36  
Old 07-30-2010, 12:02 PM
johnpost johnpost is online now
Guest
 
Join Date: Jul 2009
there can be confusion with terms and regulations and this also depends on where and when.

in the USA, at one time, if a person was on city water (with a metal water main) the water pipe going out of the house was the house grounding electrode and the electrical grounded conductor from the fuse/breaker box was connected to this. if the water pipe going out of your house wasn't metal (for 8 feet or more) then you used a grounding rod as your grounding electrode. if you have the water pipe as your house grounding electrode it is still OK as long as it is maintained and remains 8 feet of metal outside the house.

all the metallic water pipes in your house should be grounded for safety. the metal water piping should not be used as a grounding path for your house electrical system (except as the grounding electrode as mentioned above).
Reply With Quote
  #37  
Old 07-30-2010, 12:16 PM
Claude Remains Claude Remains is offline
Guest
 
Join Date: Oct 2004
Dude, ground yer pipe to yer lips and fire away!
Reply With Quote
  #38  
Old 07-30-2010, 12:26 PM
GusNSpot GusNSpot is offline
Member
 
Join Date: Mar 1999
Location: N/W Arkansas
Posts: 5,242
All of the above. I'm old and made all the mistakes, just ain't figured out I'm already dead.

If us humans always did it the right way, there would never be an accident. How's that been working?

I enjoying wiring up my shop I built. I did it all and it is better than code but I had never thought of 2 separate circuits to the same outlet, either 2 or 4 plex. This I will think about.

I hate working on my old house wiring that is goofy as can be. I don't even trust pulling the mains it is so bad. they mush have thought the copper was gold and saved every penny, wires guitar string tight, no excess in outlets, shared neutrals and I still have switches that only work when some other switch is in only one position. some switches are hot but control nothing I can find..... Need to win the lottery so I can have the place stripped and totally rewired.

I gave up and added the circuits from the mains box, put the wired under the house and back up through the floor so I could have good juice in our computer room.

It is a rock house and I'm not sure it can be rewired to all the things in it now without some major remodeling... ::; sigh :::
Reply With Quote
  #39  
Old 07-30-2010, 12:42 PM
alice_in_wonderland alice_in_wonderland is offline
Guest
 
Join Date: Mar 2001
Quote:
Originally Posted by rbroome View Post
Most of the time they avoid a shock. The other times, I am told one gets used to it. I hate the feeling and always turn off the breaker, but many electricians don't. (I am not an electrician BTW, just a homeowner with some experience in wiring)
My husband got a 277 volt shock at work a couple of weeks ago and he was REALLY lucky as his arm happened to be touching a copper pipe next to the box so the current went in his finger tips and out his forearm, not crossing anything particularly critical to living.

He was VERY shaky for the rest of the evening, and has assured me that you certainly wouldn't 'get used to it'.

(In case anyone was wondering, he was shocked because his coworker screwed up and turned on the breaker that was turned off without checking that anyone was working. This wasn't a residential job - it was commercial and I'm not sure of the actual details of the device hubby was working on).
Reply With Quote
  #40  
Old 07-30-2010, 01:11 PM
johnpost johnpost is online now
Guest
 
Join Date: Jul 2009
Quote:
Originally Posted by alice_in_wonderland View Post
(In case anyone was wondering, he was shocked because his coworker screwed up and turned on the breaker that was turned off without checking that anyone was working. This wasn't a residential job - it was commercial and I'm not sure of the actual details of the device hubby was working on).
if his place of work hasn't implemented a lockout procedure, or at least a tagout procedure, then they should.
Reply With Quote
  #41  
Old 07-30-2010, 01:14 PM
flight flight is online now
Guest
 
Join Date: Mar 2000
First, God I hate shared neutrals. That is some lazy, dangerous wiring. I once was changing a ceiling fan in a friend's old house. I killed the breaker before starting. While I was up there the friend turns the lights on in the kitchen and 'poof', on goes the light in my hands. Turned off the main after that.
Quote:
Originally Posted by Hari Seldon View Post
Every two outlet circuit in my kitchen (there are three of them) is wired to two separate circuits (the same two). The electrician who did this said the code required it. The reason he gave was that in a kitchen you might be tempted to plug in a toaster in the top and a coffee maker in the bottom and that would exceed the 15 amps of one circuit. Of course, there is no reason I couldn't plug the toaster into the top of one of the outlets and the coffee maker into the top of a different one, with the same effect. Nonetheless the point above is well taken. Unless you have tested every outlet, don't assume that if one is off, so is the other.

I suppose I could replace a live outlet, but I'll be damned if I would try.
OK, that was a confused electrician. My (amateur) understanding is that new installations and remodels require two 20 amp breakers for kitchen outlets (not 15, but I am not sure if that is a code requirement or just a recommendation) but they are generally run to different outlets. So, half of the outlets will be on one circuit and half on another, but both plugs on a single outlet will be on the same circuit.

Still, you should always be wary of the potential of one plug being on one circuit and the other on a different one. This should be readily apparent as soon as you open the box. It is usually done so that you have one standard wall plug while the other one is dedicated to a lamp that is controlled by a wall switch. I am unsure if the lamp plug is usually included on the outlet breaker or the overhead light breaker (haven't had cause to install this way before). For any given room the overhead lights and the outlets should be on separate breakers if for no other reason than to make it easier to work on one (while getting light from the other).
Reply With Quote
  #42  
Old 07-30-2010, 01:15 PM
Chronos Chronos is offline
Charter Member
 
Join Date: Jan 2000
Location: The Land of Cleves
Posts: 54,072
Quoth dmatsch:
Quote:
I was an electronics engineer in the Air Force, so I know how it feels to get bit by 110 (5000v, 15,000v). It's the amperage. 1/4 of a volt will kill you if it's > .01 amp.
People are always saying that it's not the voltage that kills you, it's the amperage, but that's really misleading, since for any given resistor (like, say, the human body), there's a 1 to 1 correspondence between voltage and current. And really, when you look at the actual processes involved, it's not the volts or the amps that kill you: It's either the watts or the hertz.
Reply With Quote
  #43  
Old 07-30-2010, 01:23 PM
Joey P Joey P is online now
Charter Member
 
Join Date: Jun 1999
Location: Milwaukee, WI
Posts: 21,104
Quote:
Originally Posted by alice_in_wonderland View Post
(In case anyone was wondering, he was shocked because his coworker screwed up and turned on the breaker that was turned off without checking that anyone was working. This wasn't a residential job - it was commercial and I'm not sure of the actual details of the device hubby was working on).
LOTO
Reply With Quote
  #44  
Old 07-30-2010, 01:32 PM
johnpost johnpost is online now
Guest
 
Join Date: Jul 2009
Quote:
Originally Posted by Rick View Post
So I open up the box. Unscrew the hot grab it with my hand and move it over to the new outlet and screw it on, no problem.
On the neutral side there are two wires, one comes in the bottom of the box, and the other comes in the top. I unscrew the lower wire and move it to the new outlet. I unscrew the top wire and grab it, and get the mother loving shock of my life. It traveled up my right arm, around my rib cage and out my back where it was leaning against my new gas stove. I say gas, because gas pipes are buried in the ground and are well umm grounded.
It turns out that I got shocked by a shared neutral. That wire that went out the top of that outlet went to the light on the ceiling that was on another circuit. When I disconnected the lower wire I broke the ground connection, and that upper wire became live with 120V looking for a ground. It found one though my body.
I hate shared neutrals.
using a device (receptacle in this case) to provide neutral conductivity is an electrical code violation in the USA
Reply With Quote
  #45  
Old 07-30-2010, 02:09 PM
alice_in_wonderland alice_in_wonderland is offline
Guest
 
Join Date: Mar 2001
Quote:
Originally Posted by Joey P View Post
Quote:
Originally Posted by alice_in_wonderland View Post
(In case anyone was wondering, he was shocked because his coworker screwed up and turned on the breaker that was turned off without checking that anyone was working. This wasn't a residential job - it was commercial and I'm not sure of the actual details of the device hubby was working on).
LOTO
Lord of the Oranges?

FWIW, his company does have a lockout procedure which they may or may not follow and the doof that flipped the switch was actually the site supervisor. They're not suppose to work live, ever.

Hubby assures me that the supervisor is actually not a twit, but I'm not convinced. However, that job is wrapped up and hubby is now on a different project with a different supervisor who hopefully is a bit more on the ball.
Reply With Quote
  #46  
Old 07-30-2010, 02:16 PM
engineer_comp_geek engineer_comp_geek is offline
Robot Mod in Beta Testing
Moderator
 
Join Date: Mar 2001
Location: Pennsylvania
Posts: 8,214
LOTO = lock out / tag out

The way it is supposed to work is the guy doing the work turns off the breaker and installs the lock or tag on the breaker so that no one else will turn it on. When the guy is done working, he removes the lock/tag and turns the breaker back on.

Only the guy who installed the lock or tag can remove it. It doesn't matter if Mr. Doofus is the site supervisor, president of the company, or whatever. He can't remove the tag and flip the breaker on since he's not the one who put the tag on in the first place. At least that's the way it is supposed to work. Obviously it didn't work in this case.
Reply With Quote
  #47  
Old 07-30-2010, 02:16 PM
md2000 md2000 is offline
Guest
 
Join Date: Feb 2009
Yeah, my father-in-law helped me change the outlets in my house when we remodelled. It was an old house, and we needed to change to 3-prong. He had worked with electricians and showed me how to do it carefully. Fortunately the wiring had been 3-wire (grounded) to the metal outlet boxes even if the plugs weren't, so it was easy to hook up a safe ground.

Theoretically, you never touch anything to anything (or to yourself) to complete a circuit, so it's no different than the wires just sitting in the wall - until you go "oops".

You unhook the wires one at a time from the old outlet and attach to the new socket- first the two white, then the two black; do the ground last or first; don't touch anything. I still burned one outlet when it touched the side of the box while being pushed in.

And yes, any house but especially the older ones- wiring can be wonky.Reversed black and white are common - especially if some DIY amateur like me has added an outlet and not understood colour-codes. Even the pros are sometimes useless; a friend once had a (electrical) fire in the house he rented out, the fire department turned off the power, and he got a shock while checking for what needed to be repaired. The mains were hooked up backward, so the FD turned off the neutral connection.

I recall the building engineer where I worked hitting the roof when he found that some departments were talking to a guy who sold dimmable flourescent light kits. In our large building, he said, they ahd wired a LOT of common neutrals - several phases charing a neutral in 3-phase wiring. Dimming flourescents by clipping the power wave would create out-of-phase power in amps vs. voltage - the additive amperage if phases overlapped could overload the neutral and set the building on fire.

So, yes you can do anything live. I have accidentally touched an exposed wire when I was a kid, and my dad once had me hold the spark plug to the engine block while he cranked the lawnmower. My unprofessional observation - electricity hurts like hell.

So if you really don't know for sure what you are doing, don't. Or, in the words of John Belushi from Animal House - if you can't fly, don't f*ck with the eagles.

Last edited by md2000; 07-30-2010 at 02:17 PM..
Reply With Quote
  #48  
Old 07-30-2010, 02:19 PM
Lare Lare is offline
Guest
 
Join Date: Jun 2010
My Dad worked as a construction electrician and had this device that took multiple padlocks.
https://www.signet.net.au/App_Assets...hasp_10257.jpg
Everyone had their own padlock and there were no master keys. When locking out a circuit, he put his padlock on the device--which made it impossible for anyone to throw the switch and energize the circuit. If someone else was working on the same circuit this person added his own padlock. There could be up to 6 padlocks on the lockout device and no one could re-energize the circuit until all the padlocks were removed.
Reply With Quote
  #49  
Old 07-30-2010, 02:20 PM
alice_in_wonderland alice_in_wonderland is offline
Guest
 
Join Date: Mar 2001
Quote:
Originally Posted by engineer_comp_geek View Post
LOTO = lock out / tag out

The way it is supposed to work is the guy doing the work turns off the breaker and installs the lock or tag on the breaker so that no one else will turn it on. When the guy is done working, he removes the lock/tag and turns the breaker back on.

Only the guy who installed the lock or tag can remove it. It doesn't matter if Mr. Doofus is the site supervisor, president of the company, or whatever. He can't remove the tag and flip the breaker on since he's not the one who put the tag on in the first place. At least that's the way it is supposed to work. Obviously it didn't work in this case.
Ahh - yes!! We discussed this. Apparently hubby wasn't given a lock/tag, and neither were any of the other guys on site - only Mr. Supervisor. Now, hubby and I have agreed that from now on he will insist on getting his tag (nothing like an 8.5 months pregnant wife getting all hysterical/screaming/yelling/crying on your ass to motivate) and using it, but I still think supervisor is kind of a boob.
Reply With Quote
  #50  
Old 07-30-2010, 02:27 PM
johnpost johnpost is online now
Guest
 
Join Date: Jul 2009
Quote:
Originally Posted by md2000 View Post
Even the pros are sometimes useless; a friend once had a (electrical) fire in the house he rented out, the fire department turned off the power, and he got a shock while checking for what needed to be repaired. The mains were hooked up backward, so the FD turned off the neutral connection.
the neutral should only be switched if the hot wires are also switched at the same time, a ganged switch.

your story is incomplete as to how the fire department turned off the power; did they do so with a switch or disconnect wires.

what you've said doesn't make sense to me as you've stated it.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 08:17 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@chicagoreader.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Publishers - interested in subscribing to the Straight Dope?
Write to: sdsubscriptions@chicagoreader.com.

Copyright 2013 Sun-Times Media, LLC.