Electricity... so magical! So deadly!
September 22, 2011 12:22 PM Subscribe
Am I going to electrocute myself with my home extension cord repair?
So I cut off the male end of my 100' extension cord some time back and I'm finally getting around to repairing it. I bought something similar to this and have rewired it. I stripped the extension cord wires, wrapped the copper bits around the right... poles (I think) and sealed the thing up. I've got black on the big bit and the other two (white & green) around the other bits. What will happen if I have the other two on backwards? I'll be plugging this into a new, grounded outdoor outlet. Will it just not work if it's wired incorrectly? Or am I going to blow myself sky high? What's the best way to safely test this?
So I cut off the male end of my 100' extension cord some time back and I'm finally getting around to repairing it. I bought something similar to this and have rewired it. I stripped the extension cord wires, wrapped the copper bits around the right... poles (I think) and sealed the thing up. I've got black on the big bit and the other two (white & green) around the other bits. What will happen if I have the other two on backwards? I'll be plugging this into a new, grounded outdoor outlet. Will it just not work if it's wired incorrectly? Or am I going to blow myself sky high? What's the best way to safely test this?
Best answer: Acutally, yes I think you will give yourself a nasty shock.
If I understand what you mean properly you have black on the "big bit", meaning the one alone and round-ish. That is wrong and unsafe. The green wire (ground) should connect to the big half-circle. The white one (neutral) should connect to the larger of the two flat blades. The black one (hot) should connect to the smaller of the two flat blades.
As you have it now, when you plug something you will likely cause all the exposed metal parts of whatever you're plugging in to become 'hot', touching them will lead to painful shocks and other badness.
Once you've wired it up right you can use one of these to test it: Outlet tester.
Be safe.
posted by true at 12:32 PM on September 22, 2011 [2 favorites]
If I understand what you mean properly you have black on the "big bit", meaning the one alone and round-ish. That is wrong and unsafe. The green wire (ground) should connect to the big half-circle. The white one (neutral) should connect to the larger of the two flat blades. The black one (hot) should connect to the smaller of the two flat blades.
As you have it now, when you plug something you will likely cause all the exposed metal parts of whatever you're plugging in to become 'hot', touching them will lead to painful shocks and other badness.
Once you've wired it up right you can use one of these to test it: Outlet tester.
Be safe.
posted by true at 12:32 PM on September 22, 2011 [2 favorites]
You could use a multimeter or simple Continuity tester to check that the wires are attached to the same pole as the female end.
posted by cmdnc0 at 12:34 PM on September 22, 2011
posted by cmdnc0 at 12:34 PM on September 22, 2011
Don't plug this in until you know what black, green, and white mean. I'm seconding true here, sounds wrong, sounds like you've grounded incorrectly. A correctly set up and functioning setup of fuses and circuit breakers in your house wiring will catch your mistake - BUT - don't take that chance. Parachutes can fail.
posted by krilli at 12:36 PM on September 22, 2011
posted by krilli at 12:36 PM on September 22, 2011
Out of curiosity,what was your rationale for not putting the eight bucks you've already spent on the repair towards a new extension cord?
posted by crankylex at 12:37 PM on September 22, 2011
posted by crankylex at 12:37 PM on September 22, 2011
Best answer: Electrical outlets use alternating current, so unlike with batteries (which provide direct current) the "poles" of the circuit don't really matter. Polarity flips back and forth 50-60 times a second (50-60Hz).
The problem, as true points out, is that it sounds like you may have connected one of the power leads to the round ground prong rather than the parallel power prongs. This is no good. Not only are you more likely to shock yourself, given that power is going somewhere it isn't supposed to, but it's possible that you could fry anything into which you plug this thing.
So use an outlet tester and see what you've got. Worst that happens is that you fry the tester, which is pretty much what they're for. Next worst thing is that nothing happens. Or it could work just fine--we can't actually see what you've done here, so it's hard to say.
For future reference, here's the color code for electrical wiring. It sounds like you're in the US, so you need to put the black and white wires on the parallel, rectangular prongs, and the green one on the ground.
Good luck.
posted by valkyryn at 12:38 PM on September 22, 2011
The problem, as true points out, is that it sounds like you may have connected one of the power leads to the round ground prong rather than the parallel power prongs. This is no good. Not only are you more likely to shock yourself, given that power is going somewhere it isn't supposed to, but it's possible that you could fry anything into which you plug this thing.
So use an outlet tester and see what you've got. Worst that happens is that you fry the tester, which is pretty much what they're for. Next worst thing is that nothing happens. Or it could work just fine--we can't actually see what you've done here, so it's hard to say.
For future reference, here's the color code for electrical wiring. It sounds like you're in the US, so you need to put the black and white wires on the parallel, rectangular prongs, and the green one on the ground.
Good luck.
posted by valkyryn at 12:38 PM on September 22, 2011
As everyone has pointed out, worst case scenario here isn't the cord not working. What you could do, is you could electrify the casing of whatever you plug into this such that when you touch it, you are electrocuted. It would be safer (though still not really "safe") to just leave the ground prong ("the big bit") unwired.
Just buy a new cord. Electricity is best not learned about by diy trial-and-error.
posted by mr_roboto at 12:45 PM on September 22, 2011
Just buy a new cord. Electricity is best not learned about by diy trial-and-error.
posted by mr_roboto at 12:45 PM on September 22, 2011
Response by poster: "Green is ground." I knew that, too. Sheesh. Thanks y'all. This is what I get for trying to just get it done in a spare moment. Screw it, I'm buying a new cord....
posted by amanda at 12:45 PM on September 22, 2011 [4 favorites]
posted by amanda at 12:45 PM on September 22, 2011 [4 favorites]
Yeah, dunno why you'd risk it on something so easily replaceable. Good call.
posted by tremspeed at 12:47 PM on September 22, 2011
posted by tremspeed at 12:47 PM on September 22, 2011
so unlike with batteries (which provide direct current) the "poles" of the circuit don't really matter. Polarity flips back and forth 50-60 times a second (50-60Hz).
This is not correct. The black wire must go to the smaller flat prong and the white to the wide flat prong. Doing it the other way around will reverse the neutral and hot and can lead to a very dangerous electrocution hazard. The green goes to the round or U shaped prong.
Yeah, dunno why you'd risk it on something so easily replaceable. Good call.
A good 100' foot extension cord can easily cost over a $100. It'll certianly cost more than the replacement end.
posted by Mitheral at 12:56 PM on September 22, 2011 [6 favorites]
This is not correct. The black wire must go to the smaller flat prong and the white to the wide flat prong. Doing it the other way around will reverse the neutral and hot and can lead to a very dangerous electrocution hazard. The green goes to the round or U shaped prong.
Yeah, dunno why you'd risk it on something so easily replaceable. Good call.
A good 100' foot extension cord can easily cost over a $100. It'll certianly cost more than the replacement end.
posted by Mitheral at 12:56 PM on September 22, 2011 [6 favorites]
wrapped the copper bits around the right... poles (I think)
ummm... based on those few words alone, I think you should get an electrically-competent person to take a look at it IRL before you plug it in anywhere. I'm not exactly filled with confidence that any part of this job has been done correctly or safely.
if you know what you're doing, it's a 5 minute job. if you cannot verify 100% that the job has been done correctly, just bin it and buy a new one.
posted by alan2001 at 1:01 PM on September 22, 2011
ummm... based on those few words alone, I think you should get an electrically-competent person to take a look at it IRL before you plug it in anywhere. I'm not exactly filled with confidence that any part of this job has been done correctly or safely.
if you know what you're doing, it's a 5 minute job. if you cannot verify 100% that the job has been done correctly, just bin it and buy a new one.
posted by alan2001 at 1:01 PM on September 22, 2011
Mitheral has it correct. You can not just reverse the neutral and the hot. That is dangerous. And if it is a good extension cord, it is definitely worth doing $5 repair that will take 5 minutes.
However, if you do not know what you are doing, then maybe you should just buy another one. A little bit of knowledge can be surprisingly dangerous with electricity.
posted by Flood at 1:12 PM on September 22, 2011
However, if you do not know what you are doing, then maybe you should just buy another one. A little bit of knowledge can be surprisingly dangerous with electricity.
posted by Flood at 1:12 PM on September 22, 2011
(Note that - I THINK - there's a difference between US and European house wiring codes. Mixing up the non-ground poles is OK in Europe there's some kind of global breaker that catches this. In the US, you're in trouble. Hence the orientation-sensitive plugs and sockets in the US, and Euro plug having an indistinguishable up and down.)
posted by krilli at 1:47 PM on September 22, 2011
posted by krilli at 1:47 PM on September 22, 2011
Krilli - Houses in Europe use 240v for their basic lighting and receptacle (plugs) circuits. The US uses 120v.
posted by Flood at 1:54 PM on September 22, 2011
posted by Flood at 1:54 PM on September 22, 2011
A good 100' foot extension cord can easily cost over a $100. It'll certianly cost more than the replacement end.
Might cost less than replacing something plugged in at an improperly wired end though.
posted by yohko at 2:34 PM on September 22, 2011 [1 favorite]
Might cost less than replacing something plugged in at an improperly wired end though.
posted by yohko at 2:34 PM on September 22, 2011 [1 favorite]
Best answer: Here's what the three pins of electrical outlets do when they're properly wired:
1. Ground pin: quite literally wired into the ground. Appliances with exposed metal parts are supposed to have those parts internally connected to the ground pin.
The idea of the ground wiring is that you are sometimes connected to the ground (e.g. if you're barefoot on a damp floor) and that there should never be any voltage difference between the part of you that's touching the ground and the part of you that's touching some electrical appliance. Ground wiring acts as a short-circuit around your body.
The ground wire is supposed to be completely independent of the actual electricity supply from the street, and only in the case of an electrical fault will it ever carry current.
In modern installations the house's ground connection point is a dedicated spike pounded into the soil. Really dodgy old wiring sometimes relies solely on a ground connection to the water pipes. If your house is wired that way, and there's electrical leakage somewhere in the house so that the ground wire actually does carry a small current, the water pipes can end up with a small voltage on them; if you feel a tingle under your fingernails while standing in the shower and adjusting the taps, get your wiring looked at and possibly modernised.
2. Hot/active and neutral pins: Both of these connect to the electricity supply, and it's the voltage difference between hot and neutral that drives current through your appliances.
The reason that one of those pins is called "hot" and the other is called "neutral" is because there's never supposed to be a voltage difference between the neutral wire coming from the street and the ground in your house; in fact they should be wired together at the main supply cabinet. If all is working well and properly wired, then in theory you could hold a bared neutral wire in your hand, stand on a wet concrete floor, and not get a shock. You might get a tingle if the neutral wire is carrying current from some other circuit.
The hot pin is the one that will shock you.
The fact that the supply is AC (Alternating Current) just means that for a nominal 110V supply, the voltage on the hot pin (with respect to the neutral pin) is vibrating between +160V and -160V; it does not mean that the hot and neutral pins are continuously swapping roles with respect to ground.
However, it's worth treating both those pins with equal respect - it's not unknown for outlets to be wired wrong, simply because switching the hot and neutral wiring won't stop appliances from working. Appliances work on the voltage difference between hot and neutral, and the fact of their being designed to work on AC makes them insensitive to polarity.
Electrical faults that result in hot and neutral becoming connected to each other, or hot being connected to ground, cause large currents to flow, and those are the faults that fuses or overload circuit breakers are designed to make safe.
In normal operation, any current that flows in the hot wire is exactly balanced by an opposite flow in the neutral wire. The only way those currents are ever different sizes is when there's some degree of connection to ground - maybe via the ground wire, or maybe via you or a child or pet. This is not supposed to happen by design. A residual current detector, aka safety switch or ground fault interrupter, detects even very small imbalances between hot and neutral currents and disconnects the circuit when it sees one.
US wiring generally uses black insulation on the hot wire, white on neutral, and green or none on ground.
Very old Australian wiring has red for hot, black for neutral and green for ground, but almost all of it now is brown for hot, blue for neutral and green/yellow stripe for ground; I believe this latter standard is also common in Europe.
This article on safe wiring is well worth reading.
posted by flabdablet at 10:52 PM on September 22, 2011 [1 favorite]
1. Ground pin: quite literally wired into the ground. Appliances with exposed metal parts are supposed to have those parts internally connected to the ground pin.
The idea of the ground wiring is that you are sometimes connected to the ground (e.g. if you're barefoot on a damp floor) and that there should never be any voltage difference between the part of you that's touching the ground and the part of you that's touching some electrical appliance. Ground wiring acts as a short-circuit around your body.
The ground wire is supposed to be completely independent of the actual electricity supply from the street, and only in the case of an electrical fault will it ever carry current.
In modern installations the house's ground connection point is a dedicated spike pounded into the soil. Really dodgy old wiring sometimes relies solely on a ground connection to the water pipes. If your house is wired that way, and there's electrical leakage somewhere in the house so that the ground wire actually does carry a small current, the water pipes can end up with a small voltage on them; if you feel a tingle under your fingernails while standing in the shower and adjusting the taps, get your wiring looked at and possibly modernised.
2. Hot/active and neutral pins: Both of these connect to the electricity supply, and it's the voltage difference between hot and neutral that drives current through your appliances.
The reason that one of those pins is called "hot" and the other is called "neutral" is because there's never supposed to be a voltage difference between the neutral wire coming from the street and the ground in your house; in fact they should be wired together at the main supply cabinet. If all is working well and properly wired, then in theory you could hold a bared neutral wire in your hand, stand on a wet concrete floor, and not get a shock. You might get a tingle if the neutral wire is carrying current from some other circuit.
The hot pin is the one that will shock you.
The fact that the supply is AC (Alternating Current) just means that for a nominal 110V supply, the voltage on the hot pin (with respect to the neutral pin) is vibrating between +160V and -160V; it does not mean that the hot and neutral pins are continuously swapping roles with respect to ground.
However, it's worth treating both those pins with equal respect - it's not unknown for outlets to be wired wrong, simply because switching the hot and neutral wiring won't stop appliances from working. Appliances work on the voltage difference between hot and neutral, and the fact of their being designed to work on AC makes them insensitive to polarity.
Electrical faults that result in hot and neutral becoming connected to each other, or hot being connected to ground, cause large currents to flow, and those are the faults that fuses or overload circuit breakers are designed to make safe.
In normal operation, any current that flows in the hot wire is exactly balanced by an opposite flow in the neutral wire. The only way those currents are ever different sizes is when there's some degree of connection to ground - maybe via the ground wire, or maybe via you or a child or pet. This is not supposed to happen by design. A residual current detector, aka safety switch or ground fault interrupter, detects even very small imbalances between hot and neutral currents and disconnects the circuit when it sees one.
US wiring generally uses black insulation on the hot wire, white on neutral, and green or none on ground.
Very old Australian wiring has red for hot, black for neutral and green for ground, but almost all of it now is brown for hot, blue for neutral and green/yellow stripe for ground; I believe this latter standard is also common in Europe.
This article on safe wiring is well worth reading.
posted by flabdablet at 10:52 PM on September 22, 2011 [1 favorite]
US wiring generally uses black insulation on the hot wire, white on neutral, and green or none on ground.
This is not entirely correct. US wiring uses green or bare copper for ground. White or Gray for neutral. And all other colors for hot, including black, red, yellow, orange, blue, and purple. In standard residential 3wire, you commonly have black, white, and green. However, it is very possible (and allowable by code) to have other colors.
It is a huge mistake to tell people that black is the only color that will shock you.
posted by Flood at 1:24 AM on September 23, 2011 [1 favorite]
This is not entirely correct. US wiring uses green or bare copper for ground. White or Gray for neutral. And all other colors for hot, including black, red, yellow, orange, blue, and purple. In standard residential 3wire, you commonly have black, white, and green. However, it is very possible (and allowable by code) to have other colors.
It is a huge mistake to tell people that black is the only color that will shock you.
posted by Flood at 1:24 AM on September 23, 2011 [1 favorite]
The rule of thumb when attaching plugs to cable when you've got a standard black/white/green cable is that green is ground, the black wire goes to the brass terminal (black/brass) and the white to the silver terminal. Of course, with electricity, if you're not sure, don't risk it. Have someone knowledgeable double check your work, or just buy a new one.
posted by Morydd at 6:10 AM on September 23, 2011
posted by Morydd at 6:10 AM on September 23, 2011
Just take it to your local friendly knowledgeable (so, not Home Depot or Lowe's) hardware store and ask them for help. They'll get you fixed up in no time.
posted by xedrik at 3:00 PM on September 23, 2011
posted by xedrik at 3:00 PM on September 23, 2011
Best answer: And Mitheral is correct on the wiring. Neutral (White) goes to the larger of the two blades. Ground (Green, or bare) goes to the round or U-shaped third blade. Hot (Black, or other color) goes to the smaller of the blades.
l |
o
View looking head-on at the plug (not the wall socket), smaller/upper-left blade is hot (black, or other color); larger or upper-right blade is neutral (white), and bottom-center is ground.
Generally on a NEMA 5-15 (3-prong) plug, the blades will not be different sizes ("polarized") as they are on 1-15 (2-prong) plug. So you can't necessarily go by blade size for wiring up hot and neutral. But the orientation in the above diagram is correct.
Also, make sure you securely tighten the sheath clamp at the bottom-end of your new plug, whether it's molded in or an external clamp. Once I have the plug properly wired and closed up, I generally try to push in just a little bit of cord into the plug, and then tighten the clamp securely. This will give you some strain relief so that if someone just yanks on the cord, the stress isn't all going directly to your newly-wired contacts.
You can do this!
posted by xedrik at 3:18 PM on September 23, 2011
l |
o
View looking head-on at the plug (not the wall socket), smaller/upper-left blade is hot (black, or other color); larger or upper-right blade is neutral (white), and bottom-center is ground.
Generally on a NEMA 5-15 (3-prong) plug, the blades will not be different sizes ("polarized") as they are on 1-15 (2-prong) plug. So you can't necessarily go by blade size for wiring up hot and neutral. But the orientation in the above diagram is correct.
Also, make sure you securely tighten the sheath clamp at the bottom-end of your new plug, whether it's molded in or an external clamp. Once I have the plug properly wired and closed up, I generally try to push in just a little bit of cord into the plug, and then tighten the clamp securely. This will give you some strain relief so that if someone just yanks on the cord, the stress isn't all going directly to your newly-wired contacts.
You can do this!
posted by xedrik at 3:18 PM on September 23, 2011
This thread is closed to new comments.
posted by Marky at 12:31 PM on September 22, 2011