Type of RCD required for HP

[JamesPa]

9 hours ago, sharpener said:

 

Do you have a view on fitting a 32A Loadstar mcb into a Starbreaker board @Mattg4321? AFAICS they are 100% mechanically compatible and are of course made by the same manufacturer.

 

If I did that I could feed it via a jumper from the incoming (line) side of the Type A RCD rather than from the busbar, so then the HP current would not go through the Type A unit at all and then there would be no risk of it being blinded.

 

(Installer says he has been told Electrium will launch Wylex Type B RCDs later this year and so probably Crabtree ones in 2025, however that is not much help to me.)

It sounds like your arrangement mean no RCD protection for the hp circuit, is this a correct interpretation?

Edited July 24 by JamesPa

[sharpener]

5 hours ago, JamesPa said:

It sounds like your arrangement mean no RCD protection for the hp circuit, is this a correct interpretation?

 

No, they are proposing to put one in a sub-board, the question is where is it to be fed from. I only unearthed this (sorry) at the w/e after I sent a reminder about the type of mcbs they would need to put in my existing CU, which was the plan agreed on a site visit months ago.

 

On 21/07/2024 at 14:31, sharpener said:

So my favoured approach to the current issue is to put a 32A Type C mcb in the existing board, and then take a 4 sq mm cable to a sub-board with their Type B RCD, the meter and a 6A mcb for the control circuitry inside it. Avoids the need for any heavy gauge meter tails too. Will phone them tomorrow with this proposition.

 

They raised further objections (as you said upthread they would!), have now suggested the variant posted last night.

 

Am now starting to worry about what other surprises are to come. Also discovered at the w/e Newark have made some small changes to the thermal store design for no reason, now too late to change it. They sent the sketch to the installers but not to me, installers did not reply or check it against my original drawing or forward it to me for checking.

 

Am also wondering it they have remembered I have a sloping site and what they are going to do about it.

[Mattg4321]

22 hours ago, sharpener said:

 

Do you have a view on fitting a 32A Loadstar mcb into a Starbreaker board @Mattg4321? AFAICS they are 100% mechanically compatible and are of course made by the same manufacturer.

 

If I did that I could feed it via a jumper from the incoming (line) side of the Type A RCD rather than from the busbar, so then the HP current would not go through the Type A unit at all and then there would be no risk of it being blinded.

 

(Installer says he has been told Electrium will launch Wylex Type B RCDs later this year and so probably Crabtree ones in 2025, however that is not much help to me.)

I would seek guidance from Electrium on that one to be honest. I expect they may well say no, they are not designed to be used in that way.

[sharpener]

On 24/07/2024 at 21:27, Mattg4321 said:

I would seek guidance from Electrium on that one to be honest. I expect they may well say no, they are not designed to be used in that way.

 

Sparkie came today and is happy to go with that solution. Whether his boss ever sought Electrium's advice I did not ask, just happy about the result.