Can no longer have an 80amp supply?!

[EFLImpudence]

So, not necessary to alter anything, then.

Just limit load to 80A for tails protection.

 

[JohnW2]

I am. I thought that was all they fitted now.

I think it probably is, in mainland UK, but I have no idea about Jersey. We know that they are probably a bit different from the mainland, since I've never heard of a mainland DNO insisting that someone has a 100A supply when they've asked for an 80A one!

I think he was referring to both CUs.

If he has a single pair of tails leaving the meter which then split, then you would probably be right - but (until we hear from him) we can only guess whether or not that is the case.

Kind Regards, John

 

[Mikefromlondon]

By the way, I took this opportunity when my supplier wrote to me that they intend to swap my electric meter, I then thought what better time than now to fix a double pole 100A isolation switch next to the meter and between my old consumer unit, so that when it comes to changing my CU, I can isolate mains from this DP switch, when the guys came and did the swap, I asked them if they could terminate meter tails into the isolator, they did and I took my own time and replaced my CU without having to call then to isolate supply for the new CU.

 

[JohnW2]

By the way, I took this opportunity when my supplier wrote to me that they intend to swap my electric meter, I then thought what better time than now to fix a double pole 100A isolation switch ....

By pure co-incidence, I'm having my meter changed tomorrow (well today!) afternoon. Last time it was changed, only a few years ago, they actually asked me if I would like an isolator (in my case a 4-pole one) fitted at the same time - an offer which I happily accepted.

Kind Regards, John

 

[Mikefromlondon]

By pure co-incidence, I'm having my meter changed tomorrow (well today!) afternoon. Last time it was changed, only a few years ago, they actually asked me if I would like an isolator (in my case a 4-pole one) fitted at the same time - an offer which I happily accepted.

Kind Regards, John

makes perfect sense doesn't it John.

 

[JohnW2]

makes perfect sense doesn't it John.

For most people, yes (although some moan that it introduces an extra point of potential failure into the installation!). I actually hardly needed it myself, since I already had an up-front time-delayed RCD in each of the three phases, which can be used to isolate (and, conveniently, to isolate just one phase).

In my case, there were really only two benefits from my getting the isolator ... the only one which really mattered to me is that it would facilitate replacement of one of the TD RCDs if that ever became necessary. The second, of no great concern to me -) ) is that it makes my installation a little more BS7671-compliant, by providing a "single point of isolation" for the entire installation!

Kind Regards, John

 

[Mikefromlondon]

Yes true, and even in cases where you have pre-pay meters, you don't need one, let the credit run out and you have automatic isolation!

 

[phatboy]

Hi, seems this thread got busy overnight!

There are 2 pairs of tails leaving the meter. It's actually 3 tariff. 1 pair is for the storage heaters only, marked off-peak. The other pair is marked 'general domestic', and has a day rate and a night rate. I get 8 hours of off-peak storage heating, in a 4 hour night block, and 2x 2 hour day blocks.

I would not have space for any additional switches, this is all located in a cupboard in the hallway.

Thanks
Tim

 

[phatboy]

 

[phatboy]

Also, the supply is approved for 100amp, the cutout was replaced a year ago and a new earth provided.

 

[Mikefromlondon]

You have more 3 pin sockets in that switchboard cupboard alone than I have in my entire living room! one lucky man with 3 terrifs as well.

( In short a 100A supply or meter is not going to make you use all 100Amps, but it allows for any increased energy needs in future.Just that you are worried about the size of your meter tails, so if you were able to provide a double pole isolator switch near the meter or just below it, even if sideways, you could then replace your meter tails in your own time to handle 100amps, without having to ask them to come and isolate it for you and incur additional charges. They would wire their meter tails capable of handling 100A into your DP isolator and then you reconnect your new 100A CU tails into it.)

 

[ban-all-sheds]

I would not have space for any additional switches

 

[JohnW2]

.... so if you were able to provide a double pole isolator switch near the meter or just below it, even if sideways, you could then replace your meter tails in your own time to handle 100amps, without having to ask them to come and isolate it for you and incur additional charges.

He has two sets of meter tails, hence would require two isolator switches to do as you suggest. Unless he actually wanted isolators, I'm not sure that would offer a benefit over simply changing the tails now (if he feels he has to).

Kind Regards, John

 

[EFLImpudence]

Ok. I was wrong about one switch by thinking it was a new installation.

However, haven't we decided that at least the off peak doesn't need an additional fuse as the tails will be protected by the heater OPDs?
So, one switch for the 24 hour supply if not protected by the OPDs or, indeed, maximum demand.


This still comes back to the definition of a 100A supply. The DNO has installed a 100A supply - i.e. cables rated for a 100A fuse.

This does not alter the fact that an 80A fuse can replace the 100A one if you so wish.

 

[JohnW2]

Ok. I was wrong about one switch by thinking it was a new installation.

What we're seeing might still be the norm for new installations in Jersey.

However, haven't we decided that at least the off peak doesn't need an additional fuse as the tails will be protected by the heater OPDs?

I'm not sure that anyone has "decided" that, but it corresponds with common sense. It obviously leaves any faults within the tails themselves (very unlikely) getting fault protection only from the cutout fuse.

This still comes back to the definition of a 100A supply. The DNO has installed a 100A supply - i.e. cables rated for a 100A fuse. ... This does not alter the fact that an 80A fuse can replace the 100A one if you so wish.

Electrically, that's obviously true, but I can't speak for the policies of the Jersey DNO. As you say, the provision of a 100A supply seems to be a fait accomplis. However, I'm not clear as to whether phatboy has asked (if such is what he would like) if they could put in an 80A cutout fuse, despite it being a "100A supply".

Kind Regards, John