An electrical question...

[TC10284]

Hey all,

Last night when my sister was using her hair drier, my parents noticed that an outlet they were plugging something into in my room was very warm to the touch. The outlets that were very warm did not have anything plugged into them. The outlets that did have something plugged in were not as warm.

My theory is (and please understand that I am not an electrician), the hair drier was sucking down a lot of current (because those things do obviously). I believe the three bedrooms in our house are all on the same breaker/circuit. Since all that current was running through the same circuit/wires to power the hair drier, the outlets with nothing plugged in became warm because the extra power had not much of a place to go compared to the outlets with something plugged in. Is this anywhere accurate? Also, is there any immediate danger with these outlets? They obviously shouldn't get that warm, but what can be done besides having her plug the hair drier (or iron) into a dedicated circuit?

 

[her209]

Your outlets are connected in parallell not in series

 

[TC10284]

Then, in other words, comparing to Christmas lights, if you disconnect one bulb, the rest after it will stop working (in general terms)?

 

[SagaLore]

Originally posted by: her209
Your outlets are connected in parallell not in series

Is that always the case?

So what is the answer to his question about the warm outlets?

I think he should turn the main breaker off, open the outlet cover, and see if its grounding properly and doesn't have any wires touching the box.

 

[her209]

Originally posted by: TC10284
Then, in other words, comparing to Christmas lights, if you disconnect one bulb, the rest after it will stop working (in general terms)?

If you disconnect one, all of them will go out (before and after).

 

[SagaLore]

Originally posted by: TC10284
Then, in other words, comparing to Christmas lights, if you disconnect one bulb, the rest after it will stop working (in general terms)?

No, in series would be the way christmas lights works. He's saying that each outlet terminates back at the circuit breaker - they aren't connected to each other in any way. I can't verify though 'cause I don't know.

edit:
I don't know what I'm taking about. I'm thinking DC, not real good with AC. Don't mind me.

 

[her209]

Originally posted by: SagaLore
So what is the answer to his question about the warm outlets?

In other words, if he doesn't have anything plugged into the outlet that is on the same circuit, no electricity is flowing to that outlet EVEN if another outlet on the same circuit is being used, e.g., the hair dryer.

 

[T9D]

If the entire line is being overloaded it could cause the wire and outlets to get warm. Your outlets can be on that same line that the hairdryer was on.

 

[her209]

Originally posted by: tk109
If the entire line is being overloaded it could cause the wire and outlets to get warm. Your outlets can be on that same line that the hairdryer was on.

But wouldn't the circuit breaker trip at that point?

 

[T9D]

Originally posted by: her209

Originally posted by: tk109
If the entire line is being overloaded it could cause the wire and outlets to get warm. Your outlets can be on that same line that the hairdryer was on.

But wouldn't the circuit breaker trip at that point?

May be just at the border of tripping. The line could also be really old or run to long and have to much resistance. Could have also put the wrong size breaker for the size wire they used.

 

[kranky]

Originally posted by: tk109
Could have also put the wrong size breaker for the size wire they used.

If that's the case, it's potentially unsafe and needs to be corrected.

 

[TC10284]

Originally posted by: SagaLore

No, in series would be the way christmas lights works. He's saying that each outlet terminates back at the circuit breaker - they aren't connected to each other in any way. I can't verify though 'cause I don't know.

edit:
I don't know what I'm taking about. I'm thinking DC, not real good with AC. Don't mind me.

So then, the reason the other outlets are getting hot is because the same amount of current is going to each outlet regardless if it is using it or not?

This page helps me understand a little. But I am still unsure as to why the outlets got warm: http://www.uvi.edu/Physics/SCI3xxWeb/Electrical/Circuits.html

 

[dmcowen674]

15 Amps at 110Volts is a lot of heat (current) 1,500 Watt hair dryer.

That's why Europe uses 220Volts. Takes only 7,500 watts to get the same heat.

Breaker didn't trip, so as long as everything is in good shape and up to code should be fine.

 

[Batti]

Originally posted by: dmcowen674
Breaker didn't trip, so as long as everything is in good shape and up to code should be fine.

There's the catch. I'm thinking poor connections at the outlets that got warm. Maybe the ones with things plugged in acted like a heat sink so it was not as noticable. You should have the outlets checked to see if they are "back-stabbed". That's a push-in connection as opposed to a screw terminal, and there have been problems with those.

Look here

 

[Born2bwire]

15 Amps at 110Volts is a lot of heat (current) 1,500 Watt hair dryer.

That's why Europe uses 220Volts. Takes only 7,500 watts to get the same heat.

Breaker didn't trip, so as long as everything is in good shape and up to code should be fine.

Power is heat, not current, so it would not matter if he was on 230V or 120V.

 

[TC10284]

Originally posted by: dmcowen674
15 Amps at 110Volts is a lot of heat (current) 1,500 Watt hair dryer.

That's why Europe uses 220Volts. Takes only 7,500 watts to get the same heat.

Breaker didn't trip, so as long as everything is in good shape and up to code should be fine.

I'm not sure where you get 7,500w.

Sorry, I'm trying to understand as much as I can. I know (or think) that you can calculate the amp (current) by dividing watts by volts.

 

[her209]

Remember you're dealing with AC not DC also.

 

[dmcowen674]

Originally posted by: TC10284

Originally posted by: dmcowen674
15 Amps at 110Volts is a lot of heat (current) 1,500 Watt hair dryer.

That's why Europe uses 220Volts. Takes only 7,500 watts to get the same heat.

Breaker didn't trip, so as long as everything is in good shape and up to code should be fine.

I'm not sure where you get 7,500w.

Sorry, I'm trying to understand as much as I can. I know (or think) that you can calculate the amp (current) by dividing watts by volts.

You got it. :thumbsup:

 

[DrPizza]

Originally posted by: Batti

Originally posted by: dmcowen674
Breaker didn't trip, so as long as everything is in good shape and up to code should be fine.

There's the catch. I'm thinking poor connections at the outlets that got warm. Maybe the ones with things plugged in acted like a heat sink so it was not as noticable. You should have the outlets checked to see if they are "back-stabbed". That's a push-in connection as opposed to a screw terminal, and there have been problems with those.

Look here

That's exactly what I was going to suggest. In all likelihood, your outlets are daisy-chained together (not a bad thing), but the wires are connected to your outlets by using the push inserts on the back of the outlet, rather than screwed down on the sides. I don't know why they make them that way; it adds resistance because the contact area is so small.

With the breaker turned off, simply unscrew one of the outlets that got warm from the box. Look at how the wires are connected. 10 to 1 says they're pushed into the back. If that's the case, then fixing the problem is a piece of cake. Don't forget, if the outlet is warm, so is the wire. You really don't want the plastic insulation to melt or become brittle eventually.

 

[Toastedlightly]

DONT TOUCH IT!

 

[DrPizza]

Originally posted by: dmcowen674

Originally posted by: TC10284

Originally posted by: dmcowen674
15 Amps at 110Volts is a lot of heat (current) 1,500 Watt hair dryer.

That's why Europe uses 220Volts. Takes only 7,500 watts to get the same heat.

Breaker didn't trip, so as long as everything is in good shape and up to code should be fine.

I'm not sure where you get 7,500w.

Sorry, I'm trying to understand as much as I can. I know (or think) that you can calculate the amp (current) by dividing watts by volts.

You got it. :thumbsup:

But, you don't get the same heat with 7500 watts. Heat is energy, and watts are the rate at which that energy is supplied. With 220 volts, you have half the current, not half the watts for the same amount of heat.

 

[dmcowen674]

Originally posted by: DrPizza

Originally posted by: dmcowen674

Originally posted by: TC10284

Originally posted by: dmcowen674
15 Amps at 110Volts is a lot of heat (current) 1,500 Watt hair dryer.

That's why Europe uses 220Volts. Takes only 7,500 watts to get the same heat.

Breaker didn't trip, so as long as everything is in good shape and up to code should be fine.

I'm not sure where you get 7,500w.

Sorry, I'm trying to understand as much as I can. I know (or think) that you can calculate the amp (current) by dividing watts by volts.

You got it. :thumbsup:

But, you don't get the same heat with 7500 watts. Heat is energy, and watts are the rate at which that energy is supplied. With 220 volts, you have half the current, not half the watts for the same amount of heat.

The conversion occurs at the point of resistance more so with the 220, much like transformers.

Easy, just trying to keep it simple for those that this stuff is new for.

 

[iamwiz82]

Originally posted by: DrPizza

Originally posted by: Batti

Originally posted by: dmcowen674
Breaker didn't trip, so as long as everything is in good shape and up to code should be fine.

There's the catch. I'm thinking poor connections at the outlets that got warm. Maybe the ones with things plugged in acted like a heat sink so it was not as noticable. You should have the outlets checked to see if they are "back-stabbed". That's a push-in connection as opposed to a screw terminal, and there have been problems with those.

Look here

That's exactly what I was going to suggest. In all likelihood, your outlets are daisy-chained together (not a bad thing), but the wires are connected to your outlets by using the push inserts on the back of the outlet, rather than screwed down on the sides. I don't know why they make them that way; it adds resistance because the contact area is so small.

With the breaker turned off, simply unscrew one of the outlets that got warm from the box. Look at how the wires are connected. 10 to 1 says they're pushed into the back. If that's the case, then fixing the problem is a piece of cake. Don't forget, if the outlet is warm, so is the wire. You really don't want the plastic insulation to melt or become brittle eventually.

To be sure, check he temp of the circuit breaker. An overloaded circuit will cause both sides to be warm, whereas a poor connection will only heat up one side. I just ran into this a few months ago with my cooktop. The cooktop side was getting up to 140F while the cirucit breaker was at room temperature. It ended up being a connection that just wouldn't stay with wire nuts, I ended up using split bolts and problem was solved.

 

[DrPizza]

Originally posted by: dmcowen674
The conversion occurs at the point of resistance more so with the 220, much like transformers.

Easy, just trying to keep it simple for those that this stuff is new for.

Are you suggesting that half of the power is lost to I squared R losses in the wire?? The difference between the two systems is meaningless; for the same amount of heat, you need the same wattage. The only difference is that we have twice the amps at half the volts in the U.S. (Or, they have twice the volts and half the amps.) The power loss in the wires is pretty negligible.

 

[jagec]

Originally posted by: DrPizza
The power loss in the wires is pretty negligible.

Well, clearly not, if the OP's outlets are getting warm

I think he's saying that since a 220V dryer will have a higher resistance for the same heat output, the resistance of the wires is less of factor, and they won't get as warm. Which is true, but if you have to rely on tricks like that to keep your outlets from overheating, clearly something is wrong and needs to be fixed.

Originally posted by: TC10284

So then, the reason the other outlets are getting hot is because the same amount of current is going to each outlet regardless if it is using it or not?

This page helps me understand a little. But I am still unsure as to why the outlets got warm: http://www.uvi.edu/Physics/SCI3xxWeb/Electrical/Circuits.html

Current only travels if there is a path. Each outlet is being supplied with a 110V potential, yes, but there will be no current flow until you plug something in, or cause a short.

It seems strange that the outlet would ONLY get warm while you're using something else in the circuit. Normally, if it had some kind of internal short, it would be warm all the time. It's possible that something else in the circuit is getting hot and the heat is being carried up the wire. It would have to get pretty hot to make the other outlet perceptibly warmer, though, so something is seriously wrong. I'd stop using that circuit until I get it fixed, if I were you.

One thing you can try is to get a multimeter, and check the resistance of the wires. Turn off the circuit breaker, unplug everything from that circuit, and measure the resistance from the wire to ground. It shouldn't register at all--if it does, you've got a short. You're looking for infinite resistance (or rather, much higher than the meter can measure). Now measure the resistance of an appliance (like the hairdrier) when it's on. Plug it into the circuit (the breaker's still off, right?) Measure the resistance again. It should be pretty much the same as the resistance of the appliance by itself, plus a few ohms or so. If it's higher, something is not making good contact, or maybe the wires are starting to rot. If it's lower, there is a short somewhere.