The Straight Dope

Go Back   Straight Dope Message Board > Main > General Questions

Reply
 
Thread Tools Display Modes
  #1  
Old 03-01-2012, 07:32 PM
Caveat lector Caveat lector is offline
Guest
 
Join Date: Jul 2008
Help! Plugged my surge protector into an extension cord and got sparks.

I recently had a major electrical disruption in the place I rent where the cord from the meter to the breaker box got messed up. Part of the electrical items shut down, part of them browned out, and part of them got extra power. They fixed the problem, but two outlets still don't work. One of them was by my computer.

No problem, though I, I'll just run an heavy duty extension cord from the one that does work to the surge protector for the PC (the surge protector is one of those fancy ones with a replacement guarantee). Plug extension cord into the wall. No problem. Plug extension cord into surge protector....zapping noises and smoke immediately start coming from the protector. I pulled the plug and put the smoking protector outside.

Was I stupid by plugging the protector into the extension cord or is it possible that outlet is still pulling too much juice? I plugged in a lamp I don't care about into the outlet and it survived, but its twin survived the original power surge with no problem.
Reply With Quote
Advertisements  
  #2  
Old 03-01-2012, 07:58 PM
johnpost johnpost is offline
Guest
 
Join Date: Jul 2009
have your place looked at by the owner's electrician. your place seems to still have damaged wiring or receptacles.

your surge suppressor or computer may have been damaged by the electrical surge caused by the faulty building wiring. your insurance or the owners insurance may cover the damage to your stuff.
Reply With Quote
  #3  
Old 03-01-2012, 08:41 PM
Al Bundy Al Bundy is offline
Guest
 
Join Date: Apr 2010
miswired

I believe that receptacle is still not wired properly.
The light is just looking for power. If the voltage were too high, yes the bulb would be brighter and could burn out right away. I don't expect over voltage. I suspect cross wiring. The surge protector is expecting a hot, neutral and ground. Maybe the hot and neutral are reversed. The light would not know the difference.

You could easily check this with a simple VOM from the hardware for about $10. Or you could buy a universal socket checker for about $3 that has three neon lights and a legend that tells the status of the wiring at that point. When I do home inspections, this is the easiest way to verify wiring at an end point.
Reply With Quote
  #4  
Old 03-01-2012, 09:10 PM
Caveat lector Caveat lector is offline
Guest
 
Join Date: Jul 2008
Thanks for the replies so far. I am also considering the possibility that the protector was damaged in the original event and the reaction might have been due to that.
Reply With Quote
  #5  
Old 03-02-2012, 12:52 AM
Snnipe 70E Snnipe 70E is offline
Guest
 
Join Date: Oct 2008
Quote:
Originally Posted by johnpost View Post
have your place looked at by the owner's electrician. your place seems to still have damaged wiring or receptacles.

your surge suppressor or computer may have been damaged by the electrical surge caused by the faulty building wiring. your insurance or the owners insurance may cover the damage to your stuff.
I agree. If you have two outlets that are still not working there is still something wrong.

I would not plug the computer in any outlet until the voltage is checked on all outlets.

If you replace your surge protector I advise a good one. In our high rise building we lost the neutral on one set of circuits. When I checked the voltage at one outlet I got 190 VAC. The computers protected by the cheap surge protectors had the smoke let out of them. The ones protected by the expensive surge protectors the smoke was let out of the surge protectors and the computers were OK.
Reply With Quote
  #6  
Old 03-02-2012, 02:16 AM
aceplace57 aceplace57 is offline
Guest
 
Join Date: Oct 2009
The better surge protectors have leds that indicate if the receptacle is wired correctly. They're really good for catching ungrounded receptacles.

Some surge protectors are only meant to take one major "hit". That major surge fries the surge protector instead of your thousand dollar computer. You buy another $25 surge protector and you're protected again.

If a throw away protector was used again after taking a hit they shouldn't provide any power. They're designed to simply "die" after a major surge. Definitely shouldn't get any sparks from a dead one.

They make them also with a external push button breaker. But, I prefer the ones with internal diodes or fuse resistors because they can react more quickly to a surge than a mechanical breaker. milliseconds matter when a surge comes through and is threatening expensive equipment.

Last edited by aceplace57; 03-02-2012 at 02:21 AM..
Reply With Quote
  #7  
Old 03-02-2012, 08:48 AM
westom westom is offline
Guest
 
Join Date: Jul 2009
Quote:
Originally Posted by Caveat lector View Post
Thanks for the replies so far. I am also considering the possibility that the protector was damaged in the original event and the reaction might have been due to that.
Grossly undersized protectors fail during a surge to promote sales. These ‘one shot’ devices are often designed with a thermal fuse to disconnect protector parts as fast as possible. So that a house fire does not result. And so that you will recommend that protector.

Unfortunately it does not always work properly. Many protectors did what yours did. Some even created house fires. Be concerned.

A protector designed 'to simply "die" after' any surge is only a profit center. Designed to disconnect its protector parts even on surges too tiny to damage any appliance. And leave a surge connected to the appliance. Grossly undersizing promotes sales and increases profits. Promotes rumors that were even posted above. And sometimes create a threat that you saw.

Profit center strip protectors have a thermal fuse to disconnect its protector parts. And a 15 amp circuit breaker to protect you. Its thermal fuse did not blow fast enough creating a fire threat. The (typically 15 amp) circuit breaker would not trip; left your computers connected to AC mains. All power strips (even non-protector strips) must have that circuit breaker. It is essential for human safety.

Power strip protectors should be located where sparks or flame will not cause a house fire. IOW do not use such protectors on a rug or behind furniture. Or even better, use power strips without protector parts. Then use something completely different; a different device (also called a protector) that does effective protection for everything. Not just the computer. It remains functional after every surge. Effective protectors are not ‘one shot’ devices. And do not create that fire threat.
Reply With Quote
  #8  
Old 03-02-2012, 08:55 AM
Chefguy Chefguy is offline
Charter Member
 
Join Date: Jun 2003
Location: Portlandia
Posts: 28,859
Quote:
Originally Posted by Al Bundy View Post
I believe that receptacle is still not wired properly.
The light is just looking for power. If the voltage were too high, yes the bulb would be brighter and could burn out right away. I don't expect over voltage. I suspect cross wiring. The surge protector is expecting a hot, neutral and ground. Maybe the hot and neutral are reversed. The light would not know the difference.

You could easily check this with a simple VOM from the hardware for about $10. Or you could buy a universal socket checker for about $3 that has three neon lights and a legend that tells the status of the wiring at that point. When I do home inspections, this is the easiest way to verify wiring at an end point.
Quite likely. Surge protectors do NOT like reversed polarity.
Reply With Quote
  #9  
Old 03-02-2012, 09:26 AM
westom westom is offline
Guest
 
Join Date: Jul 2009
Quote:
Originally Posted by Chefguy View Post
Quite likely. Surge protectors do NOT like reversed polarity.
AC electricity goes positive and negative 60 times a second. Protector parts do an equivalent of reverse polarity 60 times a second. No problem. In fact, those parts have no idea that polarity is reversed. Do not care. Remain inert (non-conductive) on both reverse or normal polarity.

Polarity exists for human safety reasons. Reverse polarity is not harmful to appliances or protectors since all appliances go positive and negative polarity 60 times per second.
Reply With Quote
  #10  
Old 03-02-2012, 11:36 AM
engineer_comp_geek engineer_comp_geek is offline
Robot Mod in Beta Testing
Moderator
 
Join Date: Mar 2001
Location: Pennsylvania
Posts: 8,594
Quote:
Originally Posted by Caveat lector View Post
Thanks for the replies so far. I am also considering the possibility that the protector was damaged in the original event and the reaction might have been due to that.
It's possible. Your typical surge protector will have things like a choke (just a coil of wire), a fuse and/or breaker, and some metal oxide varistors (MOVs). A surge could have punched through the insulation in the choke and it could be shorting out and making smoke now.

MOVs work by turning "on" when the voltage gets too high. The MOV then essentially creates a short circuit between the protected line and ground. By creating an intentional short circuit fault, the MOV clamps the incoming surge and shunts it to ground, but the MOV can only handle so much power before it gets completely fried. The higher the joule rating on your power strip, the more power the MOVs can handle before they get toasted.

Due to the way MOVs work, they are usually destroyed in the process of protecting a surge. If you are handy with electronics you can replace the MOVs yourself. Normal folks just buy a new surge protector.

MOVs may make smoke when they first blow, but I wouldn't expect them to keep making smoke when you plug the power strip in later. Either you've got a shorted choke or you've got some fancier circuit in there that's been damaged, or maybe you've still got some problems in your wiring.

Quote:
Originally Posted by Caveat lector View Post
Part of the electrical items shut down, part of them browned out, and part of them got extra power.
This makes me think that they basically lost the neutral connection. With a floating neutral, you still get 240 volts from line to line, but your line to neutrals will be proportional to the current flowing between the two circuits. So if twice as much current is flowing through one than the other you'll get 80 volts on one circuit and 160 volts on the other, for example, and those voltage values will change as the current being drawn changes. The overvoltage can cause excessive current to flow which can then cause further damage to the electrical system, to you can easily end up with much more than just the original broken neutral problem.

Surge protectors don't do diddley to protect you from brownouts, and they won't protect you from an overvoltage until the voltage gets up high enough to trigger them. Surge protectors are designed for short high voltage surges. Many of them don't offer much protection against a moderate overvoltage like what you get from a floating neutral.

Quote:
Originally Posted by aceplace57 View Post
The better surge protectors have leds that indicate if the receptacle is wired correctly.
In a good surge protector, the LEDs also won't light if the MOVs are blown. It gives you a good visual indication as to whether or not you still have good surge protection.

With your typical el-cheapo surge protector, you have no way of knowing if the MOVs already took a hit and are blown or not.

Last edited by engineer_comp_geek; 03-02-2012 at 11:38 AM.. Reason: typo
Reply With Quote
  #11  
Old 03-02-2012, 12:21 PM
Chefguy Chefguy is offline
Charter Member
 
Join Date: Jun 2003
Location: Portlandia
Posts: 28,859
Quote:
Originally Posted by westom View Post
AC electricity goes positive and negative 60 times a second. Protector parts do an equivalent of reverse polarity 60 times a second. No problem. In fact, those parts have no idea that polarity is reversed. Do not care. Remain inert (non-conductive) on both reverse or normal polarity.

Polarity exists for human safety reasons. Reverse polarity is not harmful to appliances or protectors since all appliances go positive and negative polarity 60 times per second.
Fuzzy memory strikes again for me. I was recalling the years I spent in Europe and Africa, where everybody had autotransformers for their Amerian appliances/electronics. If the AT was plugged into a reversed plug, you ended up with a 220 potential to the frame of the damn thing. When you plugged in a 120 surge protector in that situation, much fun ensued.
Reply With Quote
  #12  
Old 03-02-2012, 12:56 PM
Michael63129 Michael63129 is offline
Guest
 
Join Date: Jan 2012
Quote:
Originally Posted by Chefguy View Post
Fuzzy memory strikes again for me. I was recalling the years I spent in Europe and Africa, where everybody had autotransformers for their Amerian appliances/electronics. If the AT was plugged into a reversed plug, you ended up with a 220 potential to the frame of the damn thing. When you plugged in a 120 surge protector in that situation, much fun ensued.
That's due to the hot and neutral lines being reversed, and the neutral is connected to the frame (which shouldn't be done even if it only plugs in one way); for the surge protector, it is because 220 v is applied between neutral and ground (most appliances probably wouldn't care; some do have MOVs themselves, but usually only across the hot and neutral; line filter capacitors are virtually always rated at 250 vac or more).

Also, when one talks of "polarity" in an AC circuit, they probably mean relative to ground, in this sense, the hot wire is "different" from the neutral wire, as a short would make evident (a ground-neutral short may still trip a GFCI if there is one and current is flowing since there will be a small voltage difference).
Reply With Quote
  #13  
Old 03-02-2012, 02:48 PM
Chefguy Chefguy is offline
Charter Member
 
Join Date: Jun 2003
Location: Portlandia
Posts: 28,859
Quote:
Originally Posted by Michael63129 View Post
That's due to the hot and neutral lines being reversed, and the neutral is connected to the frame (which shouldn't be done even if it only plugs in one way); for the surge protector, it is because 220 v is applied between neutral and ground (most appliances probably wouldn't care; some do have MOVs themselves, but usually only across the hot and neutral; line filter capacitors are virtually always rated at 250 vac or more).

Also, when one talks of "polarity" in an AC circuit, they probably mean relative to ground, in this sense, the hot wire is "different" from the neutral wire, as a short would make evident (a ground-neutral short may still trip a GFCI if there is one and current is flowing since there will be a small voltage difference).
They fried a lot of motherboards at the embassy in Africa prior to my arrival, and several people had been shocked. I had to retrain the local electricians so they wouldn't do that anymore.
Reply With Quote
  #14  
Old 03-02-2012, 04:10 PM
Dallas Jones Dallas Jones is offline
Guest
 
Join Date: Apr 2008
As a general safety rule, surge protectors should be plugged directly into the wall outlet. Piggy backing using extension cords is a safety violation where I work.

But it does sound like the OP has other electrical issues.
Reply With Quote
  #15  
Old 03-03-2012, 02:19 PM
Caveat lector Caveat lector is offline
Guest
 
Join Date: Jul 2008
Thanks for the help you all. I am moving (today actually) so I will tell my landlord they need to do some more investigation to make sure everything is sound.

A slight hijack, as y'all seem knowledgeable about this, what kind of protector is recommended for my electronics when I go to replace the damaged one?
Reply With Quote
  #16  
Old 03-03-2012, 04:46 PM
engineer_comp_geek engineer_comp_geek is offline
Robot Mod in Beta Testing
Moderator
 
Join Date: Mar 2001
Location: Pennsylvania
Posts: 8,594
There are different levels of surge protection. A UPS not only provides more protection (since it isolates the load from the line) but also provides backup. However, a UPS is rather expensive.

If you are going with a regular surge protector, the things you want to look for are the response time, the clamping voltage, and the surge rating.

For the response time, the faster the better. Look for one that has a response time of a nanosecond or lower.

For the clamping voltage, the lower the better. Try to get one at least below 400 volts, preferably closer to 300 volts.

The surge rating will be in joules. This is how much energy it can absorb, so the higher the number the better. If it can only handle a couple hundred joules, then a really big surge will overwhelm the surge protection and will do damage to your electronics.

Also look for indicator lights that let you know if the MOVs are still functioning, otherwise you have no idea if your surge protection has been blown out or not.
Reply With Quote
  #17  
Old 03-03-2012, 05:06 PM
Michael63129 Michael63129 is offline
Guest
 
Join Date: Jan 2012
Quote:
Originally Posted by engineer_comp_geek View Post
There are different levels of surge protection. A UPS not only provides more protection (since it isolates the load from the line) but also provides backup. However, a UPS is rather expensive.
It should be noted that there are different types of UPSs; the most basic (and common type, usually referred to as an offline or standby UPS) only operates when there is a power disturbance; otherwise, the load is running directly off the line, although they do tend to have better filtering and surge protection than surge protectors, at least the ones I have seen internally. The best (and most expensive) type is an online UPS, which is constantly converting between line power and battery power and vice-versa for the load (i.e. think of an offline UPS with a battery charger that can also handle the load power); a surge would be very unlikely to cause damage in this case since ground is the only connection between the input and output; the input circuitry may be damaged but not the load.

(there are also terms like sine wave used to describe how the UPS produces AC; an online UPS should be sine wave since it will always be running, most offline (cheaper) UPSs produce a stepped square wave-like waveform which approximates the peak and RMS voltages of a sine wave)

Also, it is a pretty good idea to have one for your computer if you experience outages (frequency depends on how you use it; I see several a year, most for a few seconds or less), even if it is a basic offline UPS.
Reply With Quote
  #18  
Old 03-03-2012, 07:41 PM
westom westom is offline
Guest
 
Join Date: Jul 2009
Quote:
Originally Posted by Caveat lector View Post
A slight hijack, as y'all seem knowledgeable about this, what kind of protector is recommended for my electronics when I go to replace the damaged one?
Start with spec numbers. As noted earlier, grossly undersized protectors fail during a surge to promote sales. These ‘one shot’ devices are often designed with a thermal fuse to disconnect protector parts as fast as possible. So that a house fire does not result.

Compare its spec numbers to ones on retail shelves. All have the same ‘near zero’ protection. Some selling in Wal-Mart for $7 have protection equivalent to ones selling under the Monster name for $80 or $120. Read the specifications.

Protectors that sit next to an appliance and others that actually do protection are completely different devices. A protector located next to an appliance also needs protection provided by the 'whole house' protector. You already saw why.

Protection is about where hundreds of thousands of joules dissipate. How many joules did that failed protector claim to absorb? Essential in any protection system is what absorbs hundreds of thousands of joules. Every facility that cannot have damage spends money on a well proven 'whole house' protector. Then everything (including power strip protectors) is protected. Then hundreds of thousands of joules dissipate harmless away from all appliances.

View spec numbers for the UPS. It typically has even smaller protection numbers. ‘Near zero protection means a UPS can claim 100% protection in advertising and sales brochures. Protection afforded by all three types of UPS is found inside electronic appliances. Therefore even 'dirtiest' power from a UPS causes no harms. And yes, some of the dirtiest power in any house comes from a UPS in battery backup mode.

A UPS provides temporary and dirty power during a blackout. Transient protection is best done elsewhere typically for tens or 100 times less money. But again, don't take my word for it. Read the spec numbers for each device.

A minimal 'whole house' protector is designed to make even direct lightning strikes irrelevant. That spec number is even printed on its box. A direct lightning strike is typically 20,000 amps. So a minimally sized 'whole house' protector (even sold in Home Depot and Lowes) starts at 50,000 amps. Spec numbers are important. Effective protection means even direct lightning strikes to utility wires causes no household damage. Even the protector must not fail.
Reply With Quote
  #19  
Old 03-04-2012, 12:21 AM
engineer_comp_geek engineer_comp_geek is offline
Robot Mod in Beta Testing
Moderator
 
Join Date: Mar 2001
Location: Pennsylvania
Posts: 8,594
Quote:
Originally Posted by westom View Post
A minimal 'whole house' protector is designed to make even direct lightning strikes irrelevant. That spec number is even printed on its box. A direct lightning strike is typically 20,000 amps. So a minimally sized 'whole house' protector (even sold in Home Depot and Lowes) starts at 50,000 amps.
Whole house surge protectors are a good thing. but this isn't applicable to the OP since they rent. For any home owners who happen to come into this thread though they are a good thing.

If you look at the ratings for whole house surge protectors, you'll see that the joule rating is usually significantly higher than what you will find in a power strip type of surge protector. It's also good to arrest the surge where it enters your house, so whole house surge protectors are a good thing.

A whole house surge protector will not protect you from a direct lightning strike, though. There isn't anything you can buy that will do that. Commercial buildings like radio stations can protect their entire buildings, but it involves a complicated overall strategy with things like Ufer grounds, Faraday cages, and all sorts of stuff. Buying one little thing and slapping it on the entrance to your home isn't even in the same ballpark as that type of lightning protection. For a typical home owner, though, a good whole house surge protector (maybe something a bit better than what you can get at Lowes or Home Depot) is about the best you can get and still be affordable.

A power strip type of surge protector may be able to handle a few hundred joules. A whole house protector may be able to handle a few thousand joules. A direct lightning strike however contains somewhere in the neighborhood of a few billion joules of energy. That's why you can't buy a simple whole house surge protector that can protect your entire house from a direct lightning strike.

Fortunately, though, direct lightning strikes are rare. You are much more likely to get an indirect surge, which a whole house surge protector can protect you from.
Reply With Quote
  #20  
Old 03-06-2012, 11:03 AM
westom westom is offline
Guest
 
Join Date: Jul 2009
Quote:
Originally Posted by engineer_comp_geek View Post
Whole house surge protectors are a good thing. but this isn't applicable to the OP since they rent. For any home owners who happen to come into this thread though they are a good thing.
Even all renters can have a 'whole house' protector. The electric company even rents them. Puts it behind the electric meter. So simple that often the girl who reads the meter will install it.

Surge protectors are for direct lightning strikes. Surge protectors that do not connect direct lightning strikes to earth are only profit centers.

For example, view spec numbers for a power strip or UPS protector. A surge that is hundreds of joules is made irrelevant by protection already inside every appliance. We earth one 'whole house' protector so that destructive surges (ie lightning) do not overwhelm superior protection inside every appliance.

Any protector that does not protect even from lightning often costs more money. Informed homeowners have protection even from direct lightning strikes. Only protectors that are earthed will do that protection. And do not create a fire threat.

Last edited by westom; 03-06-2012 at 11:05 AM..
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 03:20 AM.


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.