What are your thoughts on this 3ph domestic.

[charlie76]

The installation on the attached pic is a property with a 3-phase supply and a range of fuse boards. I am currently in training but this is a family friend and I have discussed carrying out a rewire for them once I get my papers. I intend notifying the works to BC and then getting NAPIT in to use it as an inspection site to get my competent persons sign of.

My query with this is, I was of the understanding with a 3ph supply, the consumer was obliged to balance their load amongst the 3 phases. This has recently had new fuses fitted by the DNO and as can be seen they have quite happily only connected one of the phases. If I carry out a rewire, should I design the system to utilise all three phases and leave 3 tails for connection by the DNO when complete or is this unnecessary in a domestic system due to the minimal load?

 

[Simonslimline]

How do you know there are actually fuses in the other 2 carriers?

 

[davesparks]

As far as the installation is concerned that is an SP supply.

How far through your apprenticeship are you? It would be sensible to get your mentor to have a look at this with you.

Did the DNO guys open up the hole for the PME connection or tell you that you can use it?

 

[davesparks]

How do you know there are actually fuses in the other 2 carriers?

There aren't, they're blanks, fuse carriers will be labelled like the one on the left

 

[telectrix]

and if the wiring is all pvc, does it need a rewire? maybe an upgrade of the DBs and a tails tidy up is all that's required.

 

[charlie76]

It's a 3ph supply to the property of which only 1 phase is in use

 

[ian.settle1]

What a bloody mess

 

[charlie76]

It's not all pvc there is also VIR plus the client wants a rewire, would you talk them out of it?

 

[davesparks]

It's a 3ph supply to the property of which only 1 phase is in use

How do you know? There could be only 2 in the box.

As far as anyone working on the installation is concerned it's a single phase supply.

 

[Octopus]

It's not all pvc there is also VIR plus the client wants a rewire, would you talk them out of it?

I would do an EICR before anything else is discussed and agreed!

 

[davesparks]

If a customer comes to me asking for a rewire, and the rest of the installation is as much of a mismatched mess as the intake appears to be then I'd not argue.

 

[UNG]

It's a 3ph supply to the property of which only 1 phase is in use

How have you verified this ? just because it is a 3ph cutout doesn't always mean it's a 3ph supply

 

[davesparks]

The supply, as made available to the consumer at the suppliers terminals is single phase.

The suppliers terminals is the point of connection between the consumers equipment and the public electricity network, in this case the outgoing terminals of the electricity meter.

 

[charlie76]

How have you verified this ? just because it is a 3ph cutout doesn't always mean it's a 3ph supply

[FONT=Calibri, sans-serif]He's been told by DNO it's 3ph. Anyone want to answer the OP?





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[davesparks]

[FONT=Calibri, sans-serif]He's been told by DNO it's 3ph. Anyone want to answer the OP?





[/FONT]

Ok so the supply up to the head is TP, but that is before the meter and not part of the consumers installation.
The consumers supply is at the point of connection to the distributors network, which in this installation is single phase.

I'm surprised you haven't come across this before during your apprenticeship.

 

[charlie76]

Thanks Dave. the answer I was after.

 

[davesparks]

That's ok, it's only been said a half dozen times already in this thread.

Now, more importantly, did they say you could connect to the earth terminal in that cutout?

 

[charlie76]

That's ok, it's only been said a half dozen times already in this thread.

Now, more importantly, did they say you could connect to the earth terminal in that cutout?

It's a tns arrangement. You can't see in that photo but the existing earth is connected to the supply braid below

 

[Lucien Nunes]

Returning to the original question for a moment, the DNO are not obliged to make the three phases available, nor would they have any complaint about the lack of balancing as they have provided a single-phase supply to the customer. For all you know, there's another TP+N head next door with an SP installation on L2. If the distributor is only 3 1/2 core it's up to them to know how to balance the supplies they dish out.

There are situations in which two phases (not a two-phase supply but two of the normal three) are present, where the service cable was put in for 3-wire DC. Unlike the pic above, my head at home has two cutouts with 100A fuses in of which I only use one, because the original installation was large enough to warrant having both the outers (lines). I could request another SP supply up to 100A, but if I wanted TP they would have to dig up the road.

As to whether TP supply would make for a better installation, you haven't stated anything about the demand so we've no clues other than guessing the functions of the cables in the picture.

 

[assegayer]

only god knows how someone can walk away from an installation looking as rough as that...