Cable size - 3 Phase supply - Single phase loads

[fjr1300]

Hi All

Got a 3 phase 20A per phase supply coming in, feeding 2 gites. The owner needs the 3 phase supply to also feed a new house 66 meters away. The house will only single phase loads and probably be unbalanced most of the time

Now the tables I have, show that for a single phase - the wire needs to be 25mm sq (30Amps max - 83 meters max) but i'm thinking about the neutral wire.

If each phase is limited at 20A and the single phase loads were taking 20Amps - then would the neutral current be 60Amps ?

Is my thinking correct ?

lee

 

[Engineer54]

These units aren't RCBOS they are MCBs with adjustable trip settings incorporating an earth fault facility set at 500mA. We have exactly the same units in Cyprus...

I can't see how your limited supply of 20A per phase is going to adequately supply 2 Gites and a a new house. Time for your customer to bite the bullet and upgrade his EDF max KVA supply me thinks...lol!!

Oooops, that MCB above should be MCCB!!!

 

[Engineer54]

Going to put in a 40A/phase rated cable so that they can up the supply later.

For the house to have its own supply, EDF will start charging from 1500€ (and upwards) and the "Consuel" (Bit like a building inspector for electrical) will want to inspect the house later. - People try to avoid any Consuel inspections.
The idea behind the inspections is great, make sure everything has been installed per the regs and is safe - BUT (and it's a big but), some how a load of "wouldn't it be nice" items got added
EG.
All bedrooms must have telephone points - they've not heard of wireless phones :smilewinkgrin:

All phone points must the RJ45 type - most phones in the stores have the big French connections
Cable also has to be Cat 5 or 6 rated - 100M of old phone wire 20-30€ - Cat 5/6 out here 150-200€
(Thank god for CPC.co.uk - 300M = £60)

You must have a comms box next to the consumer unit - this has TV/phone lines coming in and RJ45 patch panel. Prices start at 160€ and got to 1000€. Great is you were building and office but not a 2 bed holiday home.

And I could go on and on especially about DCL light connectors but I won't bore you

I have perfect respect for the regs when they are there for safety reasons but when you add a load of other "but it would be nice if" under the "Safety label" it does make people start to ignore bits and some of those bits ARE there for safety

OK Rant over

Lee

With such draconian charges, is probably how EDF got the money to buy into the UK's electrical supply market!! lol!! Perhaps with the idea of trying to bring there money making tariffs with them...lol!!

You'll tend to find that every country has it's own numbty rules that hinder rather than enhance electrical installations... They have a rule in Cyprus about having a common Comm's/TV/SAT etc box, but without all the the gear. You can install what you need in the box certainly no requirement for RJ45 patch panels or even Cat cables if you don't want or need them...lol!!!

 

[sparkypaul2]

Very interesting to hear of all the other arrangements around the globe. Of course electricity does not care where it is being used, it acts the same. I can see that the members of this forum help each other to be that much better electricians.