Difference of Temperature of Live wire and Neutral wire

[Son]

Hello everyone;

As you knew, normally, from a power supply source, the current flows in the live wire to the load and through the neutral wire to neutral terminal of the source.

But why is the temperature of live wire hotter than the neutral wire ?

Please, spend your time to explain for me.

Thank you and Merry Christmas.
Son.

 

[kbsparky]

It ain't.

You are confusing temperature with potential when using the term "Hot"

It's common practice to use the term hot when describing the presence of potential difference (e.g: VOLTAGE).

While a neutral conductor will carry the same amount of current as its corresponding "live" wire, the potential difference between the individual conductors and "ground" is considerable.

If you touch a neutral conductor while standing on a grounded surface, there may be little if any effect. Try that with a "hot" conductor and it could be lethal. Both conductors carry the same amount of current in the circuit, however.

 

[Besoeker]

It ain't.

You are confusing temperature with potential when using the term "Hot"

It's common practice to use the term hot when describing the presence of potential difference (e.g: VOLTAGE).

While a neutral conductor will carry the same amount of current as its corresponding "live" wire, the potential difference between the individual conductors and "ground" is considerable.

If you touch a neutral conductor while standing on a grounded surface, there may be little if any effect. Try that with a "hot" conductor and it could be lethal. Both conductors carry the same amount of current in the circuit, however.

I wonder where Son is from......
In my experience, the term "hot" is mostly used in North America. In the UK and many of the ex British colonies, it is usually referred to as "live" - as in the title of this thread. Maybe that's a clue in itself.
Anyway, I'm sure you're right. Maybe Son wasn't familiar with the use of hot in this context.

 

[infinity]

As you knew, normally, from a power supply source, the current flows in the live wire to the load and through the neutral wire to neutral terminal of the source.

I would refrain from using this terminology. The current is alternating at 60 Hz or 60 times per second. It simply does not only flow out on one conductor and return on the other.

 

[ceb58]

While a neutral conductor will carry the same amount of current as its corresponding "live" wire, the potential difference between the individual conductors and "ground" is considerable.

Another way to in-vision what is going on is to look at a spigot and drain in a sink. The water coming out is under pressure. When it his the drain it is the same amount of water but it has now lost potential.

 

[hurk27]

Hello everyone;

As you knew, normally, from a power supply source, the current flows in the live wire to the load and through the neutral wire to neutral terminal of the source.

But why is the temperature of live wire hotter than the neutral wire ?

Please, spend your time to explain for me.

Thank you and Merry Christmas.
Son.

Welcome

In a multi-wire circuit a ungrounded conductor (live) can be warmer then the neutral because the neutral only Carry's the unbalanced current, but in a single circuit where conductors are exactly the same size and type, the heat should be close.

There can be many causes of heat in one conductor verses another, these can be induced inductively, the way the conductor was run, size, and material type its made of, a bad spot in the conductor, wire stretched thinner, load current flowing another path back to source.

checking amprage readings is a must to understand what all is going on.

 

[Jim W in Tampa]

SON we will try to help you but you need to clear up what your asking. Hot as others have mentioned is just a trade slang word for the ungrounded conductor and has nothing to do with temperature. But you will let go of it fast as if its hot should you touch it while live.
And if in a shared neutral condition the 2 LIVE (ungrounded conductors) will carry most of the current if not all so yes they actually are hotter than the neutral.

 

[Besoeker]

And if in a shared neutral condition the 2 LIVE (ungrounded conductors) will carry most of the current if not all so yes they actually are hotter than the neutral.

Yes, I thought about the possibility of a neutral in a three phase system but the question indicated one live and one neutral.

 

[Son]

Thanks to you.

According to the above answers, I could understand but whether it is true ?

- With 3 phase system : the N is only hot when the system is not balance.
- With 1 phase system : the N is the same as the ungrounded conductor.

 

[readydave8]

Thanks to you.

According to the above answers, I could understand but whether it is true ?

- With 3 phase system : the N is only hot when the system is not balance.
- With 1 phase system : the N is the same as the ungrounded conductor.

neutral carries unbalanced current.

so in single phase with a hot from each leg sharing a common neutral (MWBC), current on neutral will be the difference between current on each leg.

 

[infinity]

neutral carries unbalanced current.

so in single phase with a hot from each leg sharing a common neutral (MWBC), current on neutral will be the difference between current on each leg.

That would be true in a single phase, 120/240 volt system but it may not be true in single phase circuit from a 3 phase Wye system.

 

[kwired]

Thanks to you.

According to the above answers, I could understand but whether it is true ?

- With 3 phase system : the N is only hot when the system is not balance.
- With 1 phase system : the N is the same as the ungrounded conductor.

Neutral (if grounded on a grounded system) is same potential as ground, it will vary slightly from ground because of voltage drop when it carries current.

Forget about 1 phase vs 3 phase, you are likely wanting to ask 2 wire circuit vs multiwire circuit.

Multiwire circuits with balanced phase current whether 2 or more phases results in zero net current on the neutral. What goes in the load(s) on one phase makes its way back through the others. The neutral is needed for voltage stabilization and for if the load on a phase would increase then the neutral will carry the unbalance.

With a two wire circuit it does not matter what is hot or grounded or anything else. The amount of current on one wire of the circuit will be the same as in the other wire what goes in has to come out.

 

[roger]

Thanks to you.

According to the above answers, I could understand but whether it is true ?

- With 3 phase system : the N is only hot when the system is not balance.

You really need to quit using the term "hot", the neutral carries current in an unbalanced circuit and in a balanced circuit it would not carry any current, this would be true of a four wire three phase circuit or a three wire single phase circuit.

- With 1 phase system : the N is the same as the ungrounded conductor.

Only in a two wire circuit, in a three wire circuit it would carry no current in a balanced circuit.

In a two or three wire circuit of a three phase circuit the neutral (better described as the grounded conductor) will carry current and will in fact carry the same current as the ungrounded conductors if they are balanced,

Roger

 

[acrwc10]

It ain't.

You are confusing temperature with potential when using the term "Hot"

It's common practice to use the term hot when describing the presence of potential difference (e.g: VOLTAGE).

While a neutral conductor will carry the same amount of current as its corresponding "live" wire, the potential difference between the individual conductors and "ground" is considerable.

If you touch a neutral conductor while standing on a grounded surface, there may be little if any effect. Try that with a "hot" conductor and it could be lethal. Both conductors carry the same amount of current in the circuit, however.

This would be a really bad idea because it also could be lethal. Just think about why we need to put so much bonding around pools, if what you suggest was accurate we wouldn't need to go to such extremes.

 

[Son]

Thanks for explainings. I got it

I have used the word "hot" in order to describe the difference about temperature of the neutral conductor (grounded conductor) and the ungrounded conductor.

So, with DC circuit, as the explainings, is it the same as 2 wire circuit ?

 

[glene77is]

So, with DC circuit, as the explainings, is it the same as 2 wire circuit ?

It has been 30 years since I've seen a poly-phase DC motor circuit,
so I don't think you will ever see one.

In general,
(1) with reference to the Neutral carrying the "unbalanced" currents,
(2) 1 phase, 2 phase, 3 phase, any # phases circuits,
(3) the AC and DC circuits operate the same.

Keep reading those text-books.
Hope that helps