How dangerous is your home electrical system?

My mother was electrocuted about two years ago. While painting the outside of a house, her metal ladder touched a wire that carried all of the juice into the home. (The insulation on the wire was almost gone.) It threw her about ten feet, and burned a two-inch-deep grove into the ladder itself. Amazingly, after a short hospital stay, she was fine.

But when it comes to dangerous electricity, there’s a risk in older homes that I was not aware of until I was negotiating to purchase one. Older homes sometimes still have what’s called “knob and tube” wiring.

The inspection on our prospective home revealed that the house, built in the '20s, had this type of wiring. Curious, my husband made a few calls, and found out that it’s a huge fire risk. When we called our insurance company to inquire about coverage, they told us they would not insure the house unless the wiring was updated to code, which would mean tearing out walls to get rid of all of the old wiring, and replacing it with new.

Sometimes homeowners are not even aware that they have it. Unscrupulous electricians will sometimes “jump” the wiring into a new box to enlarge the juice flow, and this is even riskier, since the old wires can’t handle the higher loads.

I once lived in an apartment that was a converted warehouse. The landlords had reconditioned everything… but left the electrical system untouched.

The place was still wired for 220 volts, instead of the 110 that most household appliances use. Each and every power socket in that place had enough juice to run your refrigerator, or your dryer, or your washing machine.

This caused one of the light switches to explode in my hand one evening. Zapped the hell out of me, stunned me, and was otherwise an extremely unpleasant experience.

Furthermore, we all got to experience it at LEAST twice, due to the fact that it was in the main bathroom, and all us Americans are conditioned to reach out with a hand and flip on the lights when entering a dark room. Took WAY too long to get that damn switch fixed.

But, I point out, myself and my roommates are still alive…

[ul]Is there an OSHA inspector around? :p[/ul]

Well, *handy, it’s been nice knowing your.

A couple of things here.
From my Fluke Multimeter manual is a warning


and from the IEEE (page 5) I found the following


it is clear that a shock from 120V line voltage can kill if it lasts long enough. half the men could not let go at 16mA and the human body can conduct about 15 times that.

(Personal story)
I usually wire outlets live, and treat the system like the OP said as enriched plutonium. I needed to change out the outlet behind the stove one warm summer day. My wife, whom I love dearly, ragged on me to turn off the power. So to please her I plugged in a lamp and went out to the box. I flipped off the breaker and the lamp was off. Circuit is dead right?
Anyway I pulled out the stove a couple of feet and started to rewire the socket. I was leaning back against the gas stove, sweating like a pig (hot summer day remember?) I undid the hot lead and grabbed it, no problem and attached it to the new socket. I then undid the neutral (white lead), grabbed it and got the shock of my life. I felt the current run up my left arm through my chest and out my sweaty back into the stove. I could not let go of the wire, but I did manage to move my feet, and pulled away from the wire.
I found out later what happened. I had grabbed the neutral (return) wire, which is common to all the circuits in the house. Because I had only turned off the one breaker, my hot sweaty body made a good ground for the rest of the circuits, and I got juiced.
My advice is turn off all the circuits AND treat the wires like they are made from enriched plutonium

Actual Electrician Here.

Quickly; the term electrocute, electrocuted, electrocution all mean that someone has been killed by electricity.
I almost pooped myself when Lissa said her mom had been electrocuted.
See Santa`s reply.

120 volts is not to be taken lightly.
The odds of death are low, but still too high to mess with.

What causes death/damage to the body are three things.

  1. amperage
  2. the path through the body
  3. the amount of time exposed

If your not grounded or dont complete the path to another voltage phase or the nuetral then your not going to be hurt. If these conditions are met you wont even realise you are in contact with a live voltage source.

Treat all wires as though their hot and turn off the circuit before you work on it. Freak things happen all the time with electricity and it would not take much for you to be hurt/killed by house wiring.

Hi Rick. It did NOT take me twelve minutes to type that.

It took me forever to type mine as the docs I qouted from were in adobe and I’ll be dammed if I know how to C/P from them. :slight_smile:

Thanks for all the responses/stories.

Just to clarify to those who are questioning my sanity.
I do not use the “touch and swear” method to determine if a wire is hot. I was merely wondering if was likely to touch a live wire and live to tell about it.
Also one more question to the more knowledgable electrical folk: How do you work on wires without being grounded? Doesn’t just standing on the ground ground you, or will your shoes insulate you (provided, of course, you don’t have copper soled shoes!)?

Thanks again

That is the tricky part.

You can never guarantee that you are not grounded. Wearing rubber soled shoes helps. You could also stand on dry cardboard, plastic, or a rubber mat. If you do wear shoes, your feet should be dry and the soles should not be cracked or have any metal filings or nails in them. Be sure that you are not touching anything grounded with your other hand or any part of your body for that matter.

FYI - What I do if I have any doubt, and I HAVE to work on a hot circuit, is quickly tap the exposed part of the wire with my finger.
If I don`t get the TINGLE then I consider myself safe. I also wear good work boots that keep me from being grounded.

A friend of mine told me a technique he uses when working with household circuits. First, he turns off the circuit. Then he takes a screwdriver and shorts out the wires (and through Rick’s story, I’d short them to ground too.) If huge sparks fly out, the circuit is still live; otherwise it’s much more likely to be safe. Why risk your life when you can risk a hand tool instead?

Since detailed searches in burning buildings are often by feel we were taught in fire academy to pat around under and behind furniture with the back of our hand/glove for that very reason.

My big question is this.

I know that sometimes it is not feasible to shut off power before working on something (like part of a main on/off in a breaker box) is there any way to reduce the likelyhood of getting cooked like heavily insulated boots or some kind of ground strap to make you a path of greater resistance.

I have a very useful tool, but I’ll be damned if I know what to call it in English.

Basically it measures the electrodynamic field around conductors to tell you if they’re hot or not.

I don’t quite understand how it works (which is really bugging me), but it has this single wheel where you set the sensitivity, and then when you get close to a hot wire it starts beeping. A bit like a GM counter, but for EM-fields.

Since an unfortunate accident when I touched 220V (hurt like hell, but I’m here to tell the tale) I always test wires with this tool before touching.

A very handy tool for anyone fiddling with wiring.

I assume #1 refers to actual current through the body. Because the current capability of the circuit, whether it be 15 Amps or 1500 Amps, doesn’t matter…

Sounds like a good way to start a fire. Why not just purchase a $2 neon bulb tester?

This explains a lot! :smiley:

"Wearing rubber soled shoes helps. You could also stand on dry cardboard, plastic, or a rubber mat. If you do wear shoes, your feet should be dry and the soles "

Well, don’t forget gloves! They are the most important.

People can take a Taser shot, which is what, 50,000 volts? Thats kinda small compared to 120V. Does it matter if its AC or DC?

What matters is the amount of current. The tazer puts out high voltage, but damn near no current. As soon as you put a load on the terminals of the tazer, the voltage drops. A tazer has (or at least should have) a current limiter or regulator to keep the current below lethal levels. Also, a tazer jolt doesn’t normally pass through the heart.

Good questions, but you’re opening a can of worms that will result in endless discussions. Does it matter where current enters & exits the body? Yes. Is there a difference between AC and DC? Yes. Does frequency matter? Yes. Does source impedance matter? Yes. Is there a difference between peak voltage vs. RMS? Yes. Does anyone agree on all of this stuff? No.

Righto. Short and simple:
Electricity can kill you. Do you really want to discover by personal experience under just exactly which circumstances?