Rcd protection for domestic inatalls.

[APE37]

Hi guys. Am I right in interpreting the regs with regards to rcds that they need to be rated equal to or higher than the main supply fuse? So not to overload them? Or am I reading it wrong?
Thanks on advance.

 

[Nigel]

The main switch needs to me equal to or higher than the upstream OCPD or equal to or higher than the combined ratings of the downstream OCPD.

 

[Toneyz]

Hi guys. Am I right in interpreting the regs with regards to rcds that they need to be rated equal to or higher than the main supply fuse? So not to overload them? Or am I reading it wrong?
Thanks on advance.

That's my understanding of the regs now that's why in a split RCD consumer unit Hager are fitting 100A RCD's by default.

 

[APE37]

So for reference,
If you have a 100a main tncs supply and a 100a main switch and 2 rcds of 63 amps then this complies? I thought that the rcds would need to be 100a so to not overload them? Just looking at boards in catalogues and noticed that the boards come with 2 63a rcds or 80a rcds and couldn't see how these still comply the only board I can see comply is hager.

 

[APE37]

The trouble is only hager have done this and none of the other manufacturers seem to have followed suit. So cant see how they comply?

 

[Charlie_]

The total load must not exceed the rating of the incoming device or the assigned assembly rating (InA) whichever is the lower

 

[Baddegg]

Just fit rcbos....

 

[APE37]

But what if customer dont/want the cost of rcbos

 

[APE37]

Charlie, when you say the incoming device, do you mean the main switch?

 

[Andy78]

The trouble is only hager have done this and none of the other manufacturers seem to have followed suit. So cant see how they comply?

It's up to the installer how the install complies. A total potential load after the RCD less than the rating of the RCD will comply. If the potential load exceeds the rating of the RCD, an OCPD before the CU less than the rating of the RCD will comply.

 

[Baddegg]

In a domestic situation the customer rarely will have an opinion and some of the wholesalers own brands don’t cost much more than a split board...

 

[APE37]

With potential load can max diversity be taken into account?

 

[APE37]

Or total load of mcbs on an rcd

 

[l4urence]

But what if customer dont/want the cost of rcbos

Sell the RCBO's... we are electricians and we know what is right. Split load boards belong in the 80's. Things have changed, DC leakage current / electronic equipment. I don't compete with the flooding of the market with £60 complete (split load AC RCD's) boards. Explain the difference - give the option and if they want to fit the cheap board - find someone else to do it.

 

[l4urence]

Just fit rcbos....

if I could give one piece of advice - it would be this (type A RCD obviously)...

 

[APE37]

Well that's the thing I cant seem to find any manufacturer that does a type apart from hager.

 

[l4urence]

Well that's the thing I cant seem to find any manufacturer that does a type apart from hager.

Lewden... fitted a couple so far. Good price, nice quality, loads of room and a spare SPD slot right at the end (longer than the busbar). The only thing I don't like are the square grommets but hey, I'm warming to them.

 

[Andy78]

Well that's the thing I cant seem to find any manufacturer that does a type apart from hager.

Hager do type A RCDs and RCBOs
Lewden do type A RCBOs
Wylex do type A RCDs and RCBOs
CP fusebox do type A RCBOs and are a cheap and popular option at the minute.
SBS trade sales do type A RCBOs

There are probably others too.

 

[l4urence]

Hager do type A RCDs and RCBOs
Lewden do type A RCBOs
Wylex do type A RCDs and RCBOs
CP fusebox do type A RCBOs and are a cheap and popular option at the minute.
SBS trade sales do type A RCBOs

There are probably others too.

I should confess, I'm a pretty new Lewden 'fanboy'. but really like Wylex too. The only brand I'm beginning to loath (for CU's) are MK - who should be top. Their boards are rubbish (IMHO) now (for 18th) - everything else they make is great but they are falling behind big time - don't even make an SPD yet - but endorse Surge Protection Devices for use in their boards... messy!

 

[Andy78]

I should confess, I'm a pretty new Lewden 'fanboy'. but really like Wylex too. The only brand I'm beginning to loath (for CU's) are MK - who should be top. Their boards are rubbish (IMHO) now (for 18th) - everything else they make is great but they are falling behind big time - don't even make an SPD yet - but endorse Surge Protection Devices for use in their boards... messy!

I've been using Lewden RCBO boards for a couple of years or more now. Can't complain at all, apart from maybe their SPD could be a bit cheaper.

 

[ipf]

MK - who should be top. Their boards are rubbish (IMHO) now (for 18th) - everything else they make is great but they are falling behind big time - don't even make an SPD yet - but endorse Surge Protection Devices for use in their boards... messy!

Yes, their CU's aren't up to the general standards of MK..........but CU's have never been their strong point. Never touch them.
The trouble with MK is that many of their 'superior' accessories are no longer superior....even for superior prices

 

[Charlie_]

Rated diversity factor (RDF) / Values of assumed loading
1way = 1.0
2way – 3way = 0.8
4way – 5way = 0.7
6way – 9way = 0.6
10way and above = 0.5
Note: RDF only applies to continuously and simultaneously loaded circuits.
In principle, this means adjacent circuit-breakers having a load ‘on’ time exceeding 30 minutes or where a load not exceeding 30 minutes has an ‘off’ time less than the ‘on’ time, will need to have the rated diversity factor applied as indicated.