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

 

[telectrix]

as you rightly say, the separate enclosure RCD has been done to save money. as far as the regs. go. any work done has to be installed in accordance with current regs. there is no requirement to upgrade other circuits as they are not being altered. the only other thing is that the earthing and bonding must be checked and upgraded if necessary ( this is because it will have an effect on the new shower circuit, which has been installed ).

 

[tawraste]

"any work done", i understand. so that seperate rcd box could be for the sockets in a new extension kitchen?
i assume then that the remainder of an installation in this kind of example that was not up to date would simply be listed in the section "comments on existing installation" indicating that the contractor was aware but the client did not want the work done?

 

[Knobhead]

As you progress in life you will find installations that are pre 15[SUP]th[/SUP] edition. You can’t force the customer to upgrade but you must ensure your work is up to current regulations. If this means fitting a separate RCD protected CU then so be it.

You can only advise on, not enforce regulations. A dangerous installation notice can be enforced by the DNO if notified. But god help you in court it’s not correct! BTW I’ve seen a DNO inspector in Hitler mode, not a pretty sight!

Many years ago it was possible to get a disclaimer from the supply company to supply an unsafe installation. This usually came about with un-earthed brass light switches, the owner didn’t want them changed.

One day I’ll write down the episode of changing a baronial hall from DC to AC public mains.

 

[tawraste]

cheers guys, thats cleaned that up for me. this forum and it's members frequently provide far more in depth answers to things than the tutors/colleges and their courses. thanks again, now i shall return to the regs, find the section that describes the requirement for "any work done" and emblazon the reg number in my mind.
i'd like to read the story of that dc to ac conversion, stick a link here or pm me when you do!
regards,
tawraste

 

[malcolmsanford]

The very introduction to the regs on page 4 states

"Existing installations that have been installed in accordance with earlier editions of the Regulations may not comply with this edition in every aspec. This does not mean that they are unsafe for continued use or require upgrading"

And then onto reg 131.8 regarding the existing regluation which includes the earthing and bonding

 

[tawraste]

hi glenn,
could you post a link to that pack please? would be of interest. also, your boss installed an rcd instead of an rcbo because the main switch is the one in the old board?
cheers,
tawraste

 

[tawraste]

cheers malcolm!

 

[malcolmsanford]

hi glenn,
could you post a link to that pack please? would be of interest. also, your boss installed an rcd instead of an rcbo because the main switch is the one in the old board?
cheers,
tawraste

I would have assumed he fitted a double pole RCBO rather than an RCD/MCB. I would class a sub board like that as a seperate installation and so to reg 537.1.3 it should have main linked switch or a linked circuit breaker that will isolate boih LIVES.

If he had Henly blocked the tails as is normal, then by isolating the main switch on the existing CU, will not isolate the other installation covered by the sub board, and so technically then it is "another installation"

 

[telectrix]

hi, malcolm. did that CU thursday. look at the pic on my thread called yesterdays job. (incoming L tail).

 

[malcolmsanford]

hi, malcolm. did that CU thursday. look at the pic on my thread called yesterdays job. (incoming L tail).

Not to hijack the thread mate .......................bit of red tape??

 

[telectrix]

Not to hijack the thread mate .......................bit of red tape??

only had brown with me. not really a hijack tho, was a 3036 board so slightly relevant

 

[tawraste]

where there are seperate boards i can see that they will have their own means of isolation of supply, but the kind of arrangement i had in mind is where someone has literally attached a 2 way enclosure to the wall next to the old cu and wired in the protective device to the old rewireable boards' rails.
i've seen showers done this way twice, and that prompted my initial enquiry.
my question about the rcbo was based on the requirement for an rcd not to be a main switch. i.e, in the above arrangement where there is not an existing rcd, surely you would need to have an rcbo? if there was an rcd installed rated at 40A 30mA, then the rcd would not be rated to support an overload because the upstream main switch would be say, 100A?

 

[malcolmsanford]

yos malcolm, it was done through a henley block and an earth block for the earth upgrade 10 to 16mm so what you are saying is link the new board through the old board via a fuse which will be 5 second disconnection time and then you isolate everything via the old boards main switch.

No i'm saying the new board should have a double pole device as in regulation 537.1.4 for isolation at the origin of the installation. As that new CU is obviously a seperate installation within the house and should have a means of double pole isolation.

 

[malcolmsanford]

where there are seperate boards i can see that they will have their own means of isolation of supply, but the kind of arrangement i had in mind is where someone has literally attached a 2 way enclosure to the wall next to the old cu and wired in the protective device to the old rewireable boards' rails.
Yes though I would not class that as good practice. If you had a 25mm set of tails in that switch, then it would be nice a cozy, and could stretch reg 526.1. A better way in my mind to do that is feed the enclosure with the new protection devices off of a spare way in the CU, and if none are available then henly block the tails.
i've seen showers done this way twice, and that prompted my initial enquiry.
my question about the rcbo was based on the requirement for an rcd not to be a main switch. i.e, in the above arrangement where there is not an existing rcd, surely you would need to have an rcbo? if there was an rcd installed rated at 40A 30mA, then the rcd would not be rated to support an overload because the upstream main switch would be say, 100A?

On your scenario you would need either a combination of RCD/MCB or a RCBO as the RCD alone would not be giving you overload protection,

 

[nickblake]

what i will say regarding these boards although they do still comply, there are issues regarding them,the main one is you can use almost anything instead of wire ive see pieces of nail crews tin foil if it will fit through the holes it will be used , the other thing when these boards where installed the demand was very low now we have dish washers washing machines and loads of electrical appliances they were not around when the were originally installed all these appliances put greater loads on the 5419 isolators and the elasticity of these contacts go causing poor connectons and consiquent overheating and fires especially in the boards with the wooded frame holding the fuse carriers i have been to a few fire jobs where this has been the cause so would recommend they are upgraded have alook at the ESC website some intresting info on there

did a job for a guitarist he didnt have fuse wire in his carrier he had guitar strings

 

[tawraste]

yes, the esc website is brilliant. i think their downlighter safety guide needs to read by everyone, clients included. my mate's ceiling went up the other day as the cowboy diyer had not installed fire hoods.

malcolm - your reply was exactly what i was looking for. thank you very much indeed. whilst i'm doing all this learning i look at every single install i can see and try and apply what i have learned. these old boxes seem to raise more questions than anything else, especially as they seem to be in all my friends and family's houses (future pound signs in eyes loL).

 

[malcolmsanford]

Also a lot of the older 3036 boards, ie the wood backed ones, the fuse ways were not rated over 30amp, The bakerlite/plastic ones did have 40 amp ways available, normally a single one next to the switch.

 

[nickblake]

Also a lot of the older 3036 boards, ie the wood backed ones, the fuse ways were not rated over 30amp, The bakerlite/plastic ones did have 40 amp ways available, normally a single one next to the switch.

they did your right ,one thing that is also a little concerning when the DNO replace a cutout they now normally install a 80 amp fuse well they do round here , if you have one of these boards the weakest part is the main switch and that is only rated at 60 amps so there is a possability these can now be overloaded and a greater chance of fires ,dont you just love electricity eh lol

 

[Paul P]

What are the thought of the asbesdos in the fuse sheilds on the old porciline fuse ways i.e. MEM?

 

[telectrix]

hold your breath

 

[madmac]

Fire proof!:winkiss:

 

[telectrix]

asbestos ain't no problem as it takes at least 25 years for the damage to become apparent , so you get an old fart like me to remove it.

 

[1shortcircuit]

I took some pictures of an installation I spotted today. I was going to start a new thread but then I found this one whilst using the forum search function.

I hope the OP doesn't mind me adding this but it does sound like I have found an installation that was being described :thumbsup

As you should be able to see the tails come out of the meter and go straight into the new RCD Main Switch CU where tails then come out and go to the old rewire-able fuse-board.

 

[Engineer54]

What are the thought of the asbesdos in the fuse sheilds on the old porciline fuse ways i.e. MEM?

What about them??? Why would you need to touch the asbesdos flash sheilds in the first place??

There are guys on here, that would have you believe that pulling too many of those old fuses and your ''doomed'' to an early death. They don't want to listen, that these shields were made from the least harmful asbestos, and was in a form that made it less likely to become airborne. ...And that the amount in even a large fuse way board is Tiny. Plus there is rarely a need to touch or disturb the fuse shields.

If what these doom and gloom guys say had any validity to them ....i would have long since been gone!!! Training in a large industrial environment, i was exposed to far more of this stuff than most. We had a policy of replacing those shields every 5 years, section area by section area, whether they needed changing from flash damage or not!!! So as an apprentice, i've replaced literary thousands of the dammed things, ....And i might add, the shield came on a roll, so that it had to be cut to size to fit the carrier...


All you really need to stay safe when pulling rewirable fuses with asbestos flash shields, is basic ''commonsense'' !!! ..... Or as Telectrix suggested, ...get an old geezer to pull erm !!!

 

[tawraste]

no problem at all mate, keep them coming!

bit different from what i saw though. my one had the rcd after the main cu, but simply linked on to the rails with 10mm t&e. not even tails.

in your example i think they were trying to provide rcd protection for the whole install perhaps? blatantly contravening 415.1.2.

would that install be ok if it had been an rcbo rated below 60A?

edit: bearing in mind 415.1.2, how can wylex manufacture this unit with 'main switch' printed on it?

edit: whilst 415.1.2 is relevant i should have mentioned section 314 too!

 

[malcolmsanford]

Tawraste I/m not sure what your post is menaing mate.

415.1.2 alluded to having overload protection and the Bs 3036 fuses will give you that. I think your trying to evoke reg 314.1 division of the installation.

The RCD may have been fitted prior to the 17th edition in 2008 and so then not contravening any regs. It may have been fitted to the BS 7671-2008 because the system is TN-S and it may have an High Ze value because of cables being change/upgraded exterior to the installation. It may even be a converted TN-S to a TT and therefore needed 30mA protection.

What do you do if the customer didn't want the expense of a board change, you have to deal with the situation at hand, and by fitting an upfront RCD, though not a perfect solution, it does leave the installation safer.

 

[tawraste]

thanks malcolm, just after my post i remembered 314 and noticed my mistake. i was searching for reference to a rcd not being used as a main switch.

in the case of the customer in your example yes, it's definately safer - so would you then put that down as a departure form 314?

 

[malcolmsanford]

on a PIR or a EIC ?

On a PIR then no code for me, as the RCD may have been fitted under the 16th regulations. I may put a cover letter to the report advising the client of the drawbacks on this.

On an EIC I would most likely make a note of it under existing installation .

 

[tawraste]

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!

 

[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"