Isolator between meter and CU

That's the supply to the new half of the house, and it's not an RCD - just a small CU with fuse and breaker. You are right that there is no earth between the henley block and this CU. However, there is an earth wired from the earth block into that CU.

Yes, thanks ARW, I've just been downstairs and swapped the cover on the one I'm going to fit sometime this week. [g]

can't you move all those nasty li8ttle balck and red wires to come off a spare RCD in the new consumer unit?

Only if he wants the RCD to trip!

I've bought several inline 10ma RCDs from CPC, and put them in some of the ancient wiring, they should trip earlier than 30ma standard RCDs and thus give me a bit more peace of mind.

I'd do them one by one, maybe with a 10ma RCD inline, they may trip, they may not...

If one does then why?

It is just a guess looking at the age of the wiring and my experience of dealing with such cables.

As the OP is only wanting an isolator switch installing prior to doing a full rewire then it does not really matter:-)

It could well be a 100A service. Probably a 25mm single cored armoured supply. Here's one I took to bits earlier that had a 100A fuse.

I'm actually planning to fit the isolator and consolidate the existing wiring at the same time, prior to the rewire. So will put all of the existing wiring onto a new CU with 2 RCDs. Just in case I've also got the extra busbar for the CU which will allow me to fit any circuits with leakage without going through an RCD, and they'd then be earmarked for the earliest replacement.

In article , ARWadsworth writes

Thanks. The N-E bonding strap is interesting.

If you find an old circuit that trips an RCD I dont tink you should connect it up until you find out why - safer to put in an extension lead to where it was.

I'm halfway through a rewire (and a reroof etc etc), I'v taken several old circuits out of the fusebox, connected a normal 13amp fused plug to their input, then plugged them into a socket coming from a 10ma inline RCD.

Perhaps illegal, but I feel its safer.

There are a couple more shots on the wiki here (all of the same cut out).

I recommend that you do not try to extend the black rubber cables into the new CU (you asked earlier about that). It will be a lot easier to replace the feed to the main switch of that fusebox from a MCB in the new CU than it will be to work on the rubber cables. Old rubber cables have a tendancy to drop to bits when you touch them.

Thanks for the advice. I strongly suspect I'll take it.

I take it the additional connections at the bottom of the cutout would be used if the supply was "daisy-chained" to the next door house?

Yes. I also have seen the additional connections at the top used to feed an Economy 7 type of meter.(two meters in one house)

BTW Any photos of odd or unusual cut outs or meters are more than welcome if you or anyone else spot any.

In article , ARWadsworth writes

Take a look at the "What's wrong with this picture" forum at

To whet your appetite:

1. Sort out your Earthing If your supply cable is TT you need a head-end RCD, and the earth to that needs to be 4mm gr/ye 6491X in conduit or 16mm gr/ye 6491X unprotected (IIRC).

1. Sort out your Main Equipotential Bonding To Cold-Water & Gas within 600mm of entry to the building, or where "reasonably practicable" (which in most cases it is!), use 10mm gr/ye

1. Add RCD protection to each CU as a box The reason is you have a fire hazard downstream (never mind the pre-CU cabling!).

2. Disconnect house, run temporary cables off that new CU RCBOs. Personally I would fit 3-4x 20A RCBO, then 2.5mm Arctic flex (cheap from TLC, Trading Depot, easily sold back out on Ebay) to an adaptable box (cable gland off), then extension leads supplied by 1.5mm Arctic flex to 2-way or 4-way Duraplug extension strips. That gives a robust solution. You can daisy chain extension leads, but if you do please cable tie the plug in so it can not be knocked out.

You can run the lights off a 3A plug, just have a torch on each floor or buy a cheap emergency light and stick it on the same circuit.

Modern supply cables are usually split-con, not armoured - ie, do not go waving spades around because the flash & bang are big.

No they are not .