Upgrade of twin RCD box

[bsr]

Hi

For those with experience of BG Fortress...

In another post I've seen that my BG twin RCD box is no longer considered suitable as it uses type AC RCDs. The solar people also installed their circuit onto one of the RCD sections which is a bit naughty. The installation is TN-S if that makes any difference.

I'm having an extension done so will need some alterations done by a sparky soon as BC won't accept a minor works cert from me. Therefore to save cash I'm thinking I should upgrade to RCBOs and may as well add an SPD now so I'm fully 18th compliant.

Things I've thought about:

I think I'll need RCBOs, BG SPD kit, bootlace ferrules and crimper. For neatness I was thinking also to buy a new busbar, sheet of labels and the new type blanks that clip onto the DIN rail.

I'm planning on trimming the neutrals and thinking they are fine stranded so have to be ferrule crimped? Are the leads all 4mm or does it vary with RCBO rating? I believe the current range don't have a functional earth to worry about.

I'd like to get a new single neutral bar but can't find it for sale. Any ideas if there is a standard size block I can buy that will fit into the retaining clips? If not I guess I'll need to link the neutral bars, was going to cut links from the 16mm pre-cut RCD fly leads which won't be needed any more.

Would you mount the SPD right of the main switch and link the live from the MCB? Otherwise if I mount the SPD to the left of the MCB I'll need to cut a tooth out of the busbar and it seems a bigger electrical safety risk to have it running under the SPD? The kit comes with a cream functional earth lead and brown and blue links.

I was planning to use a type A RCBO for the solar inverter as that's what the manufacturer recommends. I know some people have said you shouldn't have RCD protection on the inverter due to nuisance trips.

My wiring is fairly well tested. For expedience I was planning to 250v megger at the main switch outlet but don't feel the need to redo polarity, loop impedance etc for every circuit since no one else has worked on it - unless you suggest there is a reason to. What I can't get hold of is an RCD ramp tester. Is it worth hiring?

Anything else to think of?

I thought about swapping the CU but funnily enough that would be notifiable whereas changing all the protective devices isn't! Plus the kits don't have the selection of RCBOs I need anyway.

Thanks

 

[Murdochcat]

Retro fit type A RCD’s ?

And yes the solar people made your installation more dangerous

 

[AndyPRK]

It may not be much more money to just start again or better in the long run.

Look at the fusebox brand. Or Verso

 

[ericmark]

You need to design what you want, it is not a case of just buying bits and fitting them. So in my case the CU isolator is rated 100 amp, the solar panels rated 6 kW and the battery charge at 2 kW and discharge at 3 kW but I have not looked at the rating of the inverter, however worse case scenario the DNO fuse is 60 amp and 9 kW = 39 amp so still within the 100 amp that the CU isolator is rated at.

I have two CU's as not enough room to add the solar in the original one. I also have a 3 kW UPS supply to freezers and central heating.

I did not plan it myself, as the fees and limitations of using the LABC route to notify the work was going to cost, plus doing all the paperwork for the solar panels. So the solar panel people did all the work and issued all the certificates required.

To change a consumer unit using the LABC route looking at in Wales where I live £100 plus vat to the LABC, and then depends if you can satisfy them you have the skill to inspect and test, if not then another £200 at least for the EICR they will want to be satisfied all done correctly, so looking at around £350 just to get the work signed off, seem to remember the parts for the orignal CU fitted was around £300, with new tails etc, so DIY your looking at around £650 to fit an all RCBO board, and to get a scheme member electrician to do the work will cost very little more, so simply no worth going down the DIY route.

As to test gear, when I did my perents house they wanted to see all the test gear and the calabration certificated, at that time I had it all, now my loop impedance tester and RCD tester has failed, although I have the rest, but the calabration certificate is out of date.

It is anoying as a time served electrician to have to get some one else to do the work, but the loop impedance tester and RCD testers are not cheap, I got an insulation tester for £35 new, but not the other two. And you have to test to be able to enter the figures on the installation certificate. I looked at hiring and even that was going to cost £70 so now looking at £720 to DIY.

 

[bsr]

@ericmark that's my point, by not changing the chassis of the CU then it's not notifiable! What are you saying is the issue in my design? I have a 100A DNO fuse and main switch, which is below predicted demand. No EV charger and 18 ways leaves plenty of space.

The RCBOs are £20 and the SPD kit £30 so I'd be saving £400!

 

[Murdochcat]

For expedience I was planning to 250v megger at the main switch outlet but don't feel the need to redo polarity, loop impedance etc for every circuit since no one else has worked on it - unless you suggest there is a reason to. What I can't get hold of is an RCD ramp tester. Is it worth hiring?

Really?

 

[ericmark]

@ericmark that's my point, by not changing the chassis of the CU then it's not notifiable! What are you saying is the issue in my design? I have a 100A DNO fuse and main switch, which is below predicted demand. No EV charger and 18 ways leaves plenty of space.

The RCBOs are £20 and the SPD kit £30 so I'd be saving £400!

You can get cheap (£45) plug in testers which state and will pass at 1.8Ω so only good for circuits below 24 amp. The proper tester costs around £60 to hire for a week. There are way to kid yourself you have done nothing wrong, technically a three phase distribution board is not a consumer unit, and a consumer unit with any item not listed by the manufacturer as being accepted with their type testing, makes it no longer a consumer unit.

But you know the whole idea of having a scheme member fit one is so all the testing is done, which should be done on change of occupant or every 10 years (5 for rented) which ever is sooner, and it is done for your families safety.

If you want to cut corners I can't stop you, but accept you are cutting corners, don't try and use the silly part P law as an excuse.

 

[Taylortwocities]

@ericmark that's my point, by not changing the chassis of the CU then it's not notifiable!

I havent spotted this, but if your old chassis is plastic then it will not comply with regulations, so you may as well bite the bullet and get a compliant new consumer unit.

I'm having an extension done so will need some alterations done by a sparky soon as BC won't accept a minor works cert from me

Why not have your sparky deal with the CU upgrade, then he can self-notify to LABC.

 

[EFLImpudence]

I'm having an extension done so will need some alterations done by a sparky soon as BC won't accept a minor works cert from me.

What does that mean?

Do you mean BC want an EIC and you think you are not allowed to do that?

The certificates (MEIWC and EIC) merely vary in the amount of information able to be recorded. The do not signify different types of work which some people may (are allowed to) do and others may not.

Therefore to save cash I'm thinking I should upgrade to RCBOs and may as well add an SPD now so I'm fully 18th compliant.

That definitely won't be covered by a MEIWC.

 

[bsr]

Hi @EFLImpudence

BC in my area won't accept a MWC or EIC from me as I'm not a member of a competent persons scheme (and a DIYer). I can issue one but they won't accept it even with evidence of calibrated test gear.

So if I upgrade from twin type AC RCDs to type A RCBOs now then I don't have to pay the sparky the extra to do that when he puts the sockets and lights in the extension. Plus hopefully I get an up to date board that will last for years.

I am a bit concerned that the next amendment will require AFDD on all socket circuits which is going to cost a fortune!

 

[EFLImpudence]

BC in my area won't accept a MWC or EIC from me as I'm not a member of a competent persons scheme (and a DIYer).

Ok. I just wasn't sure if you were aware of what the certificates mean.
Some people come on here and say things like "I can do that work because it is only requires a MEIWC" - not realising the type of certificate is irrelevant.

I can issue one but they won't accept it even with evidence of calibrated test gear.

Ok.

So if I upgrade from twin type AC RCDs to type A RCBOs now then I don't have to pay the sparky the extra to do that when he puts the sockets and lights in the extension. Plus hopefully I get an up to date board that will last for years.

Well, it is either part of the job so must be done or it is not so need not be done.

I am a bit concerned that the next amendment will require AFDD on all socket circuits which is going to cost a fortune!

Agreed. Just money making ruses.

 

[Murdochcat]

I am a bit concerned that the next amendment will require AFDD on all socket circuits which is going to cost a fortune!

More unnecessary expense and nonsense written in to BS7671

Problem is that the writers of BS 7671 have to come up with nonsense to justify the amendments which are thrust on the unsuspecting public and extremely frustrated Sparks

 

[bsr]

Thanks everyone, I've found a BG cu kit with RCBOs SPD etc for under £200 so I'll buy that, swap out the guts and leave the old box on the wall. Might even be able to sell the leftovers as a complete twin RCD CU on eBay!

@ericmark that plug in tester looks good, I didn't realise they did loop and RCD ramp test, I'll grab one.

@Taylortwocities it's a metal CU. I believe put in for original 18th ed. Hence me being grumpy that it's noncompliant already!

 

[ericmark]

It does test, but not a ramp test.