Thoughts on this setup

[the_jinj]

Old tenement flat in Scotland - the tails come into the flat direct to the meter then meter tails to CU. There isn't any main incoming fuse in the flat or outside door (main fuse for all flats on ground floor).

A shower has been installed with a seperate RCD fed off of the incoming side of the 100A switch in the CU (no spare ways available). So effectively there is no way of isolating the power to the RCD.

Would you have wired this differently bearing in mind that although there is no way to isolate the main board (from within each flat), if the 100A switch was thrown on the CU the RCD/shower are still juiced (no central isolation point for all circuits).

 

[BJC]

Not only can you not isolate it but you are using the main stair fuse as circuit protection. If a fault develops in your shower it is likely to take out the whole stairwell. Get it sorted. The REC will fit an isolator before your CU free of charge - certainly in Fife they do.

 

[the_jinj]

Not only can you not isolate it but you are using the main stair fuse as circuit protection. If a fault develops in your shower it is likely to take out the whole stairwell. Get it sorted. The REC will fit an isolator before your CU free of charge - certainly in Fife they do.

That's the standard way flats are wired (tenement types) - this isn't what I have, just querying as to peoples thoughts on it - I have seen it and have 2 lots of opinions on it (from different folk).

The REC won't fit that isolator as it is the way all tenements appear to be wired as standard - should have said there are a bank of fuses on ground floor - one for each flat.

As it happens I personally agree that this is the wrong way to do this....

 

[JohnD]

vague memory, this in England, might be different - there "has" to be an isolator (including removable fuse) within sight of the meter, so that a meter-changer can see that power is off and no-one's turned it on while he was working.

 

[the_jinj]

One way they could have got around it is to fit a Double Pole isolator to Henleys with one leg to the RCD and another to the CU.
Would have had to pull the fuse to all the flats though....

 

[the_jinj]

....

 

[JohnD]

One way they could have got around it is to fit a Double Pole isolator to Henleys with one leg to the RCD and another to the CU...

very good approach.

I think from the description that the installation needs, and hasn't got, a Main Switch.

 

[Adam_151]

Is there any overload protection to that shower other than the 100A BS1361 , I have heard of worse though by a rogue contractor, a henly block left where the DNO had removed a night rate meter, a shower was taken off this just through an RCD (so no overload protection and unmetered )

Doesn't seem right that there isn't any main fuse, I think sometimes in flats they are all sometimes in a separate area where the power comes in, but I think there is usually a fuseholder fitted with a solid link for isolation purposes near the meter

Reckon you could probably cut just the one flat, or possibly one or two, I don't think you'd have to shut off the old building, though finding them might be a bit tricky, and it might be a room that only the DNO have access to...

Other than live working with live tails ... cut the meter seals and pop the outgoing phase out or a section of busbar across the load side of the isolator, switch it with a broom handle while looking away, fit isolator, phone DNO to report power off

Disclaimer : Don't do any of the above

 

[JohnD]

'mmm and long tails to the main fuse on the ground floor... might be some hot tails before it blew!

 

[SparkyMarky]

Hmmm. I've never seen this type of setup before (never worked on block of flats). Without seeing it it's hard to know an acceptable way of solving the problem assuming you're stuck with the incoming arrangement as it is (non co-operative DNO etc.).

How about mounting an RCBO in a separate enclosure immediately adjacent to the CU, and supplying it from the load side of the 100A isolator? At least then you've got overload and earth fault protection provided to the shower circuit, and the 100A switch in the CU would still isolate everything....

 

[jondiy]

Why not replace the rcd unit that goes to the shower with a proper shower consumer unit, ie one with rcd and mcb protection.

This way you have your fault & overload protection, and can still use the RCD to isolate the shower (because it has 2 poles it is an acceptable isolating device!!)

If you need total isolation of all consumers, then you really need to split them tails into the henley blocks , and fit a DP isolator before the split. Personally, this is far better than looping off the main consumer outgoers, as you will get a far better connection on the tail ends, and less chance of them falling out from a slight tug!

If you are going to commence any work, make sure that fuse (The one solely for the flat!!) is off, and make sure nobody is there to put it back on whilst you are working. Having a friend to keep an eye on it while you work on the flat could prove to be very useful.

You could even install your own Switchfuse instead of a DP isolator, if you want your own protection instead of relying on the protection upstream. Obviously only install a fuse that is of a lower rating than the tails that are being used, but I'm sure if you are onsidering any of this work, then you should know all about cable current carrying capacity, correction factors, voltage drop etc , CPC size etc.

If you don't , then best leave it alone and get someone in.

 

[the_jinj]

Thanks for the replies - the reason i asked was because there were a few flats wired the same way - I am going to one tommorrow to rectify if I can.
Apparently there is a 2 way enclosure with the RCD and a blank plate so I may get a MCB for the other way (unknown make atm). No spare ways in the CU unfortunately.

Also going to try and get REC to fit that isolator if possible.