neutral-earth voltage

[One_of_them]

guys,

head is battered its been a bad day and cant think straight.

Replaced a 3kW water heater element and everything went well. Circuit tested out fine so turned everything back on but when the element is pulling im getting L-N 238 L-N 234 N-E 4V!!! This was tested at element but is the same at the supply side of the 13A DP FCU but at the board (3phase) N-E is nothing (well mV anyway) When element or FCU is off everything is normal

I have checked all relative connections and even checked another heater on site and it is the same.

Is this just the way elements are?
Why would the supply side of FCU have 4V but the board not?

cheers all have a good weekend and some lovely cold beers

 

[Moses]

Maybe when Moses was a lad but when I went to school an Amp was a coulomb of electrons passing a given point in a second. Tbh though I haven't seen an electron or proton either!

Thats what I said, I haven't seen any electrons, so cant say they exist!!!

 

[Moses]

If you think of the N cable as having some resistance (as will the L conductor).

it will be possible to pull the N conductor at the end nearest the load towards the load (supply) slightly (raising it by 4V in this case) as it (the N conductor) has a slight VD along it's length, which is proportional to the current it is passing.

the E conductor meanwhile has no load on it, as it is not passing any current, hence the slight discrepancy.

Tony may be able to post the vector/phasor drawings better than I can.

Surely if you pull the N conductor it will stretch and get thinner and increase its resistance and all your maths will be wrong and to be done again.

 

[Moses]

And there was I, believing my old lecturer when he taught us it was all about electron-hole-pair movement....

What are you saying now, we have to fit the non-existent electrons in to Holes now?
This is just silly and a farce!!!!
How can you put something into a hole when you can't see it in the first place.:flowers:

 

[spark 68]

Surely if you pull the N conductor it will stretch and get thinner and increase its resistance and all your maths will be wrong and to be done again.

Yes mate it stretches it 4V high

 

[Moses]

Yes mate it stretches it 4V high

If its stretched then it will be 4V+

 

[Knobhead]

I think I’m loosing my sanity.

How can simple physics get so twisted and convoluted.

 

[Silly Sausage]

I think I’m loosing my sanity.

How can simple physics get so twisted and convoluted.

I think Mr Moses is avin a larf
(he is an E & E engineer)

 

[Rockingit]

And the dish ran away with the spoon!

 

[Silly Sausage]

Hahaha...call me naive, but I usually prefer to give people the benefit of doubt.
Well, I hope so...