eddy currents???

[jonny1]

Does bunching lives and neutrals separately i.e terminating a distribution board cause eddy currents?

 

[bernardgreen]

Does bunching lives and neutrals separately i.e terminating a distribution board cause eddy currents?

Yes

But the effect is probably of no serious consequence

 

[jonny1]

how would you know if it could be a problem? is it the amount of cables? the distance between them?

 

[bernardgreen]

Unless the wires are coiled to make a "magnetic" coil or are carrying a few hundred amps the magnetic field from the current is unlikely to induce enough eddy currents to cause noticable warming of metal.

I have seen 300 amps at 40 volts AC ( the voltage is not important ) going up a vertical busbar on one side of a cabinet, distributed to many contactor in the middle and a bunch of several dozen wires ( but equivalent to one with the 300 amps going down the other side. So 300 amp turns and no noticable heating of the steel occurred.

Do you have a specific situtation in mind.

 

[Spark123]

Don't think it is much of a problem where all phases and neutrals are in the same enclosure following the same path as the eddys can cancel each other out, could be a different matter if theres metallic barriers inside. The favorite one which was explained to us at college is a supply from a metal 3 phase isolator to a metal trunking using 4 separate metal conduits, one for each phase and the neutral. Makes a nice route for eddys.

 

[Lectrician]

Eddy currents are an issue where the live and neutral enter a CU via differnet conduit entries / bushed entries etc.

I have seen on many PIR's where tails enter a 60a metal clad Sw Fuse etc with no noticeable problems, but always note it.

 

[jonny1]

i see a lighting control module with three 25mm couplers joining it to the trunking with the lives, neutrals and earths going through them separately....

 

[ColJack]

if it wasn't for the couplers, i would recommend cutting a slot with a hacksaw from hole to hole.. this stopr eddy currents round the individual holes, making it go round all the holes.

 

[Spark123]

Eddy currents are an issue where the live and neutral enter a CU via differnet conduit entries / bushed entries etc.

I have seen on many PIR's where tails enter a 60a metal clad Sw Fuse etc with no noticeable problems, but always note it.

From what I remember (ye oldern days) if they enter through separate holes we were told to cut a slit between the holes. Don't know if this makes much difference, I suppose the width of the metal and the current will have some bearing on this.

bah, beaten lol

 

[Spark123]

i see a lighting control module with three 25mm couplers joining it to the trunking with the lives, neutrals and earths going through them separately....

For some strange reason this sort of setup reminds me of a 3 phase transformer iron core.

 

[DESL]

Do you mean eddy currents or induced emf from electromagnetic field around cables?

 

[tim west]

Seen a 100A 3PH supply neutral at work go up in smoke for 6-8 inches above where it entered a trunking along with the phases all seperated by just an inch yet the eddies were enough to heat the neutral considerably, a specialist firm were called in and confirmed it was caused by eddie currents and as the install would have cost too much to replace, the trunking was cut in a specific pattern to create laminations which cured the problem and many years later have had no problems. moral don't run singles!

 

[Spark123]

Do you mean eddy currents or induced emf from electromagnetic field around cables?

Just really the shape of it being a good magnetic circuit.

 

[EddieCurrent]

 

[Spark123]

Ears burning la?