old rewireable fuseboxes

[tawraste]

hi everyone,
just wondering about homes that still have these old rewireable fuseboxes and where the owners want some work done.
please excuse any apparent ignorance in this or other questions i have asked/will ask, i am in the process of learning and these are hypothetic situations where i am trying to link the requirements of the regs with "real world" scenarios.

this is what has got me wondering - in a couple of properties i've been in as a visitor i've noticed (always looking now i'm learning lol) that where someone's had a shower installed, the electrician has mounted a one way enclosure to house the rcd as the old rewireable board does not have one. i always think that this arrangement looks like a "make good" scenario instead of a replacement of the cu. now i can understand that certain customers won;t have the money for a new cu, and i know that if the existing installation is still safe that cost can be factored in. however, is this acceptable under the regs?

i ask this because this arrangement always seems to leave bathroom lights and kitchen sockets etc non rcd protected, so a job has been done and the tradesman has left knowing that these special locations are not protected?!

what if new bathroom downlights were installed for example and were protected by the same method? i.e one way enclosure next to the old cu. i've never seen that arrangement! but if the shower is ok then surely this would be ok?

in my mind these kind of things do not seem the right way to go about things. but surely everyone does not walk away from a job on the basis the customer won;t pay for a full modernisation of their installation? could someone please clarify this for me ?

many thanks,

tawraste

 

[malcolmsanford]

cool, thanks again! things like this are great for getting the regs straight in my head. reading them every day and still finding more understanding is constantly required!

well if it is any consolation i've been reading the Regs from the 14yh edition and I'm still baffled by many of them

 

[1shortcircuit]

The RCD may have been fitted prior to the 17th edition in 2008 and so then not contravening any regs.

This RCD unit was only fitted last month, month before max. I believe it was done when the boiler was upgraded?

I think it was TNC-S, I'll see if I can pop back and take another peek.

I understand the part about leaving it in a safer condition it just looked a little odd having this setup.

I'm wondering if perhaps the old boiler is on a spur on the sockets and therefore had to have RCD protection installed before the new boiler could be commissioned?

 

[malcolmsanford]

I agree it does look odd, and whoever fitted it must have assessed if leaving the installation protected by a single 30mA RCD, and therefore safer, out weighed 314.1 and division of installation.

Without all the relevant facts, like Zs values for the circuits, etc it's difficult to assess the reasons for it, I have to be honest it would be perhaps the last way I would have done it.

 

[1shortcircuit]

I agree it does look odd, and whoever fitted it must have assessed if leaving the installation protected by a single 30mA RCD, and therefore safer, out weighed 314.1 and division of installation.

Without all the relevant facts, like Zs values for the circuits, etc it's difficult to assess the reasons for it, I have to be honest it would be perhaps the last way I would have done it.

Can I just run a scenario past you please?

"IF" future work was requested on this installation (Let's say an additional double socket on the downstairs ring) that no further protection would be required as the Mains Bonding is up to current regs and the Installation is protected by 30Ma RCD?

This installation is in a home owned by an elderly couple. I believe the Boiler was upgraded because they pay a small amount every year into some kind of scheme that helps them with GAS/Electric repairs? I'll try to find out more :thumbsup

 

[malcolmsanford]

Yes all future work on the installation will be 30mA RCD covered.

I have to admit that knowing that the owners of the house are an elderly couple makes the use of an upfront RCD protecting the whole insulation even more of a surprise.

How was the boiler wired, was it spurred of an existing ring final? The thing is it seems the job had been done by one of these government type scrapage schemes.

What I would have most likely done was if the boiler was spurred of the ring final. then I would have fitted an RCD for that, that way you would at least provide RCD protection to all the sockets on that circuit.

It is an hard call as we said on one hand they have left the installation safer with RCD protection, on the other you could get the situation of the whole installation tripping out leaving a vulnerable couple without power.

 

[1shortcircuit]

How was the boiler wired, was it spurred of an existing ring final?

I'm pretty sure it's spurred from the downstairs ring although I haven't checked to see for sure. I just don't recall see a dedicated circuit for it though?

on the other you could get the situation of the whole installation tripping out leaving a vulnerable couple without power.

Luckily enough they have umpteen family members close by that would drop everything and get to them as quickly as possible if needed... yes, they do have a mobile phone lol

Whilst they are elderly, they are still able and always active. It's another one of those situations though where they have lived in the same house for decades.

What I would have most likely done was if the boiler was spurred of the ring final. then I would have fitted an RCD for that, that way you would at least provide RCD protection to all the sockets on that circuit.

This is exactly how I would have expected so see it done and how I would have tackled the situation myself. :thumbsup

Thanks for your help malcolmsanford, this thread has been of great use to me.

Thanks tawraste, I'm glad I found your thread before creating my own:thumbsup

 

[1shortcircuit]

I agree it does look odd, and whoever fitted it must have assessed if leaving the installation protected by a single 30mA RCD, and therefore safer, out weighed 314.1 and division of installation.

Without all the relevant facts, like Zs values for the circuits, etc it's difficult to assess the reasons for it, I have to be honest it would be perhaps the last way I would have done it.

Hope nobody minds me continuing this :thumbsup

I manage to lay my hands on a few further details this afternoon

The home uses a TT system, 1362 Protective device supplying 3036 board.

IR Test results were recorded as

170 Mohms LN
170 " " LE
170 " " NE
170 " " L/N/E

Earth Fault Loop Impedance 17.5 Ohms

RCD Trip times 10/18 ms


The boiler is indeed spurred from the ring and there is also an additional note :-

"Recommend Fuse Board Upgrade"