Neutral terminals cooking up

[barry wilkins]

Why do the neutral terminal overheat and cook up on high powered devices ,like water heaters ,showers etc?
Is it something to do with a voltage difference between the neutral and the ground earthing at the substation ?

Barry Wilkins

[SteveNielsen]

Re: Neutral terminals cooking up

No. It is because there is current flowing through the neutral wire as it should be, but if the wire is overheating then there may be a bad neutral connection inline nearby. The bad connection adds resistance to the circuit and it dissipates the heat through the wire.

[stj]

Re: Neutral terminals cooking up

it shouldnt.

if you have a good meter, check the voltage between LNE in all 3 possible combinations.

[barry wilkins]

Re: Neutral terminals cooking up

Hi thanks for your replies ,I have seen this over the years on showers etc. A lot of info seems to say the neutral terminal works loose ,but I dont think that is the reason ,so perhaps there is a voltage on the neutral wire above the earth voltage.

Barry Wilkins

[budm]

Re: Neutral terminals cooking up

It would be contacts resistance, I see it happens to both Line and Neutral, the connection will heat up when you have high contact resistance. See attached picture.
You can check the voltage drops on the connection, just measure it, when you have the Voltage and known current then you can find out how much power will be dissipating on that bad connection.
If it is arcing you can use AM transistor radio to hear the static on the blank band on the radio.

[delaware74b]

Re: Neutral terminals cooking up

Budm - if you look at the 2 blades on that plug, the neutral side has the most damage. 95% of bad outlets (and splices) I have seen over the past 10 years have had a neutral-side failure.

I don't have a good explanation as to why neutral connections fail more than the live side, maybe harmonics.

The 2 pics I am posting were taken in a rental house I moved into in July '09. Neutral side failure, screw terminals used, burned all the neutrals to the back of the outlet box. Called landlord, told her she almost lost this house from the previous tenants. Cause: 1500 watt space heater with matching burned plug I found in a closet. I fixed the mess for $$$ off the rent

To the OP - we usually don't see terminal or outlet damage on water heaters in the US. They're usually hard-wired with 240 volts. Our 'normal' outlet circuits are only 120 volts.

[goontron]

Re: Neutral terminals cooking up

OP, showers? here we take it outta the water heater. found some pics from my old apartment (now a hole in the ground) this was my fault.

[stj]

Re: Neutral terminals cooking up

that's a point,
isnt american wiring a 120-0-120 feed that can be used as 240 and/or a pair of 120's?
so if the house has a split pair of 120 feeds from the incoming box,
what happens when you have an uneven load on the 2 lines?

[budm]

Re: Neutral terminals cooking up

"Budm - if you look at the 2 blades on that plug, the neutral side has the most damage." The blade on the right is the Line (Hot) which is badly damage.
Here is the pin out of NEMA5-15P: http://www.leadsdirect.co.uk/technic...american-plug/

goontron's pictures on post 7 also show LINE side socket is burnt.
@ST, please read this: as you can see how the current in the neutral wire flows int he branch circuit 1 and circuit 2, the unbalance of the loads on #1 and #2 will not have any affect in the neutral branch circuit.
https://cdn.badcaps-static.com/pdfs/...198de6d760.pdf
The wire from the Neutral buss bar back to the center tap of the distribution transformer is the one that share the common neutral, not the branch neutral wires.
Mike Holt has good info on NEC.
http://www.mikeholt.com/dailycodetipcalendar.php

[kc8adu]

Re: Neutral terminals cooking up

this is the perfect example of why i wont use plastic j boxes!nor backstabs.

Budm - if you look at the 2 blades on that plug, the neutral side has the most damage. 95% of bad outlets (and splices) I have seen over the past 10 years have had a neutral-side failure.

I don't have a good explanation as to why neutral connections fail more than the live side, maybe harmonics.

The 2 pics I am posting were taken in a rental house I moved into in July '09. Neutral side failure, screw terminals used, burned all the neutrals to the back of the outlet box. Called landlord, told her she almost lost this house from the previous tenants. Cause: 1500 watt space heater with matching burned plug I found in a closet. I fixed the mess for $$$ off the rent

To the OP - we usually don't see terminal or outlet damage on water heaters in the US. They're usually hard-wired with 240 volts. Our 'normal' outlet circuits are only 120 volts.

[Sparkey55]

Re: Neutral terminals cooking up

It would be contacts resistance, I see it happens to both Line and Neutral, the connection will heat up when you have high contact resistance. See attached picture.
You can check the voltage drops on the connection, just measure it, when you have the Voltage and known current then you can find out how much power will be dissipating on that bad connection.
If it is arcing you can use AM transistor radio to hear the static on the blank band on the radio.

The hot side of that plug carried the largest load. Could also be that someone wired the outlet reversed, hot wire to nuetral spade and nuetral wire to hot spade.

[goontron]

Re: Neutral terminals cooking up

The hot side of that plug carried the largest load. Could also be that someone wired the outlet reversed, hot wire to nuetral spade and nuetral wire to hot spade.

no. my socket was wired proper. my hunch was wear. top sockets where all worn more than the bottom ones, and with the bottom missing the cover material i wasn't going to try and plug anything into it. a line to earth short is not fun. especially when you have a zinsco panel...

[Sparkey55]

Re: Neutral terminals cooking up

no. my socket was wired proper.

I am talking about Budm photo not yours. Outlets in US should be wired so that the wide slot is connected to Neutral and the narrow slot is connected to Hot. The round hole should be Ground.

[goontron]

Re: Neutral terminals cooking up

I am talking about Budm photo not yours. Outlets in US should be wired so that the wide slot is connected to Neutral and the narrow slot is connected to Hot. The round hole should be Ground.

you see the chunk missing out of the top of the line pin? that says arcage. whether that was caused by the heating, or caused the heating is another story.

[budm]

Re: Neutral terminals cooking up

"The hot side of that plug carried the largest load. Could also be that someone wired the outlet reversed, hot wire to nuetral spade and nuetral wire to hot spade." The current flows from the power source to the outlet into the load in one of the terminal and the same amount of current will flow back through another terminal, the current flow reverse direction at 60 time per seconds, so how can you have more current one one terminal. If the load draw 10A of current, the 10A will flow back to source. Just put the clamp on amp meter on the hot wire and then on the neutral wire then you will see.
The plug is properly wired, the real cause of that burn plug was due to poorly crimping of the wire to the HOT blade inside the plug, we no longer use that supplier for our products. I design and build products from 10A up to 120A.
BTW, you can easily check the voltage drops on the connection, I also have to check the temperature of the blades for the UL compliance testing.

[Sparkey55]

Re: Neutral terminals cooking up

"The hot side of that plug carried the largest load. Could also be that someone wired the outlet reversed, hot wire to nuetral spade and nuetral wire to hot spade." The current flows from the power source to the outlet into the load in one of the terminal and the same amount of current will flow back through another terminal, the current flow reverse direction at 60 time per seconds, so how can you have more current one one terminal. If the load draw 10A of current, the 10A will flow back to source. Just put the clamp on amp meter on the hot wire and then on the neutral wire then you will see.

Look, all i am saying is that the Spade on the plug that you show in the photo that is the most burnt would normally be the end that is connected to the HOT SIDE of the outlet not the NEUTRAL SIDE.

[budm]

Re: Neutral terminals cooking up

Well, it is connected to the hot side and plugged into properly wire outlets, I also investigate why it burnt up. Should see what it looks like inside once we removed the molding.
The bottom line is that you can have cooked hot or neutral line on your outlets or at the plug,, The same amount of current will flow in and out of the outlets Hot and Neutral.

[ben7]

Re: Neutral terminals cooking up

To the OP - we usually don't see terminal or outlet damage on water heaters in the US. They're usually hard-wired with 240 volts.

Indeed. Besides, since the water heater doesn't get changed/unplugged often, there is really not much of a need for a plug.

that's a point,
isnt american wiring a 120-0-120 feed that can be used as 240 and/or a pair of 120's?
so if the house has a split pair of 120 feeds from the incoming box,
what happens when you have an uneven load on the 2 lines?

Yes, the L1 and L2 voltages can sag/increase, but that should not be much of an issue (if at all) when you have properly sized wiring and good connections. The big issue comes when you have a bad neutral connection, and an unbalanced load. The voltage on one leg can go up to 240, and cause damage to a lot of things.
http://www.mikeholt.com/mojonewsarch...d~20040506.php

[Longbow]

Re: Neutral terminals cooking up

All the discussion about load balancing and neutral lifting is irrelevant. Local arcing or heating in an outlet or at any connection point is caused by high contact resistance. Some HVAC guys refer to this (their term) as a series short. It is actually a point of high resistance that produces hot spots and later arcing. You can see it clearly with an IR thermometer or just measure the AC voltage drop across the terminal.

[budm]

Re: Neutral terminals cooking up

It would be contacts resistance, I see it happens to both Line and Neutral, the connection will heat up when you have high contact resistance. See attached picture.
You can check the voltage drops on the connection, just measure it, when you have the Voltage and known current then you can find out how much power will be dissipating on that bad connection.
If it is arcing you can use AM transistor radio to hear the static on the blank band on the radio.

That is what I had indicated, current leave the power source and goes into the load through one of the terminal of the AC outlet and the same amount of current returns back to the power source through another terminal of the outlet, both terminals see the same amunt of current, but some people think more current flow in one terminal than the other, if that the case the GFC type out will trip and will never work since GFC detect the difference between the Line and Neutral and tripped if unbalance occur which is around 3~5mA. The AC current also reverse direction 60 times a second.