Three phase arrives - hoo blooming ray !!!!

Mar 11, 2009 7 Replies

Regular readers will recall the saga of my trying to get a beefy (160amp) three phase supply to my barn workshop. Well at long last on Tuesday the man duly turned up to install the 'CT Chamber' (current transformer) and meters, took one look and demanded that I built a brick kiosk outside the barn to house his kit. A heated discussion followed along the lines of how come the last three EDF jobsworths a/ didn't mention this and b/ suggested a suitable internal location for it. After many phone calls and heated words he agreed to install in indoors if a/ I replaced my 160a isolator with a fused isolator and b/ converted from 'TT earthing' to 'PME earthing'. Dead sure he expected me to not have the fused isolator available so he could walk away - I gave him the choice of two saying 'you choose' !!! (good old ebay )



Then he said he hadn't enough 120mm sq cable - ok get some more then !!! Second man arrives with blue (neutral) cable but we need brown (phase) cable - ends up wrapping about three metres of cable with brown insulation tape - argh !



Bear in mind that the overhead cable is 50mm sq, the down drop on the outside of the barn is 6mm diameter aluminium (so about 28mm sq) going into their 160 amp fuses, then they have 120mm sq copper coming out - where's the sense in that?



Photos here



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Still I do now have my beefy three phase supply, albeit with the phase rotation the other way from my Transwave converter so all my machines run backwards and need two wires swapping.



Oh Joy, back to laying concrete - only another 12 cu M to go !!!!!!



AWEM



So the incomer's undersized by a factor of two and the cable after the breaker is oversized by a factor of two. Based on the assumption of 90deg thermoset ali and 70deg thermoplastic copper. I think I'd be worried about the incomer being clipped to a flammable surface... What's the rating of the fuse on the pole?

Mark Rand RTFM

200amp, and they feed not only the workshop, but single phase to my house, a pair of houses half a mile away, a sizeable mower repair business, and an environment agency yard & office block ! I certainly intend to use my i/r themometer on the drop cable when I first start firing up my induction furnace.

AWEM

Do they realize that you don't understand the concept of "diversity factor" and that a 160A supply is for supplying 160A?

How do you like life in shades of grey, brown and black, with a bit of blue?

regards Mark Rand RTFM

It's just like red, yellow, blue, and black but not nessesarily in that order

John S.

& I suppose if you get it wrong it is red, yellow and blue flashes accompanied by black smoke...

Regards, Tony

On or around Thu, 12 Mar 2009 00:01:47 +0000, Mark Rand enlightened us thusly:

I take it they've redefined the colours for 3-phase as well, then?

Have to say, the whole thing sounds remarkably odd.

Mind, I've never really been convinced by the equipment used to supply any given size of supply, I'm damned sure they work on the principle that no-one uses it all except for brief surges on startup etc.

Reminds me of that organ in the shop in Philadelphia. It's got 7 blowers and a sequencer to start them one at a time, 'cos the startup load for all 7 simultaneously would take out the power for the whole block, supposedly.

Yep - European standardisation ....

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sums it up AND shows the problems it causes with every hire company having to rewire ALL of their equipment ...

Seen something similar on an irrigation system. Pumps can only be switched on in sequence. But it only took out the local fuse - for which there were always two spare on the shelf ;)

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