Woody.v8
Blue gluer
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Exactly this, I put 3ph sockets where needed and now I wish I had put 3p+n In at every point for the minimal extra expense.still worth running 3 phase and a neutral to the point
Exactly this, I put 3ph sockets where needed and now I wish I had put 3p+n In at every point for the minimal extra expense.still worth running 3 phase and a neutral to the point
Ive had quite a few problems with this on farms where either the steel wires rust or the gland to DB connection rusts and you end up with no earth continuity. So I run a separate earth wire alongside the swa.4 core swa the steel wire outer core is used as the earth
Exactly this, I put 3ph sockets where needed and now I wish I had put 3p+n In at every point for the minimal extra expense.
how old is the install?
there was a time when negative and earth were used interchangeably in 3 phase setups.....not sure how legit it was.... that's how it was at my work years ago (build 1966) , and I've seen other old places the same
Swapping the fourth core to neutral and using the armouring only as an earth is possible but there seems to be debate about the safety of this with cores less than 6mm (this is 6mm).
There's no debate to be had, it is fine to use the armour as the CPC (circuit protective conductor) for almost any size of SWA. It only possibly becomes a problem in the larger sizes, 240mm upwards IIRC
I think it may be a bit lower, I saw a chart years ago that showed the actual CSA of the armour versus the required CSA of the CPC, I seem to recall you needed a separate CPC over 90mm² for 3 core.
very broad brush you're painting with, there.the majority of farms had 415volt single phase
Yes, that chart has been around for years, and it has been wrong for just as long.
The chart is based on the quick method of selecting CPC size (table 54.7 method IIRC) and not the long-hand method using the adiabatic equation. If you calculate the required size of CPC using the adiabatic equation you will find that the armour is almost always, if not always, suitable as a CPC.
out of interest, is aluminium wire armour suitable to use as CPC? I think not, based on the fact that I've only ever seen it in 3P&E... but interested to find out...Yes, that chart has been around for years, and it has been wrong for just as long.
The chart is based on the quick method of selecting CPC size (table 54.7 method IIRC) and not the long-hand method using the adiabatic equation. If you calculate the required size of CPC using the adiabatic equation you will find that the armour is almost always, if not always, suitable as a CPC.
should have said a minority of farms ive worked on a dozen over 50 years and possibly the same 3 phasevery broad brush you're painting with, there.