3 Phase Supply Head Question

[hamazz]

Trying to work out is this a 3 phase supply head with just 1 phase being used currently to supply house?
there are fuses in the 2 boxed on the left, but the right one was always empty like that, but there is a cable coming into it from the supply head below,
i know its not easy, but can anyone guess-timate the size of the feed cable, or max i can run off it,
as doing a full refurb+extension (Large 7 bed house) and trying to decide if i should contact uk power networks for a new cable or not (the neutral as you can see in the pic is very small)




this is for a domestic setup.


hamazz

 

[jumpin jax]

Phone uk power up, get the head changed if they will, you may only have 2 phases if in farmland, very strange fuse holder is out of last one

by the way the consumer unit busbar is live with no cover on it

 

[hamazz]

based in central london, i was thinking of getting them to change the head as it is very old, i had the meter changed about 5 months back by edf as it should have been changed last year, they did not say anything about it.

hamazz

 

[Knobhead]

Rather than paying for a new cable, why not ask for a 2[SUP]nd[/SUP] phase. The neutral is small but the cable could be 3½ core. Paper-lead cables will run at higher temperatures and currents. Unfortunately BS7671 no longer give ratings for PILC.
That R/H fuse needs a blank putting in to it.

 

[hamazz]

im planning on using the 3 phase to load balance, rather than just use 2 of the 3
i have to run air source heat pumps and ac units, and im worried at running at the max of the line cable capacity

hamazz

 

[Knobhead]

Only the DNO can answer that for you.

Best of luck with them.

 

[Deleted member 26818]

Phone uk power up, get the head changed if they will, you may only have 2 phases if in farmland, very strange fuse holder is out of last one

by the way the consumer unit busbar is live with no cover on it

Of course the covers off.
Saves having to drill holes in the side of the CU when you want to add a couple of extra circuits.
It's not dangerous or anything, look the connector block has even been taped up.
All that's needed now, is a couple of extra phases and another couple of CUs, then they can cover the lot with hats and coats.

 

[Knobhead]

Being as you're pulling the rest of it to bits, I wonder where the tails go vanishing out the top of the picture?

 

[hamazz]

ok, just had uk power networks in today after a 4 week wait, to have a look, the last uncovered phase was live, which is what i thought, they said that the cable is probably a 3.5 or 3.25 core, and that if we had alot of motors or things with pumps/fans etc the cable could not handle even the 100amp that it says on it, probably 60 amp or so max
so would be best to upgrade the cable to a new 35mm 4 core, which is what they install as standard now for 3 phase, and capable of upto 70kva, they said the existing is probably a
bout 20kva max, should be upto 40kva but the neutral is very small so they doubt that i can load on it.

now if i did load upto say 100 amps on it or more, the cable would probably blow/melt right? whose responsibility would that be to put right, mine or there's? as the holder does say 100 amp on it??


anyone with any advice,


hamazz

 

[stef]

Sorry, this doesn't make much sense to me, what do you mean with 3.5 core? Either 3 or 4 you can't have half a core.
rephrase your question please.

 

[hamazz]

Sorry, this doesn't make much sense to me, what do you mean with 3.5 core? Either 3 or 4 you can't have half a core.
rephrase your question please.

its an old three phase lead supply cable from 1950's or so, and the neutral then was half or less the size of the positive, and if you check google quickly there are still alot of the 3.5core cables being made.

hamazz

 

[Engineer54]

Sorry, this doesn't make much sense to me, what do you mean with 3.5 core? Either 3 or 4 you can't have half a core.
rephrase your question please.

Think you must be very young if you have never seen, or never heard of 3 1/2 core cables ...lol!!!

Most of the DNO'S distribution networks installed prior to the early 80's will all probably be 3 1/2 core cables, the half sized core being the neutral. They are beginning to regret the use of such cables now, due to the high harmonic and leakage currents flowing back to TX's in those half sized cables!!!

 

[Knobhead]

It’s from before the 17[SUP]th[/SUP] E54, it can’t possibly exist.

 

[hamazz]

well had skanska out to swap the supply head after a almost 2 month wait, but the DNO never mentioned to them that it was a 3 phase supply even though i specifically mentioned this. and that the engineers were not qualified to work on 3 phase, and that they would have to cut the existing service to swap the supply head then do jointing again to the cable in the footpath. as they normally do single phase supply head swaps when they are live.
so i guess more waiting for them to do anything, any ideas how i can push them along or speed up the waiting process, as we were supposed to have a full rewire, as the 2 cu's in the picture are a bit of a mess, we were waiting for the new supply head to be fitted first because of the difference in dimensions etc, to make it look all neat once we re-wire


hamazz