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Yes I know, however the same regs also state manufacturers instructions shall only be taken account of ;) they cannot have it both ways. don't you just love the IET :)
 
And another thing the RCD is not a OCPD so as long as you stick below its design current Ina things should be fine, and no you cannot just add the breakers up as that would have a massive knock on effect wrt to diversity, The effing IET don't there ar*e from their elbow.
CIBSE should take over at least they seem to know what they are doing. :)
 
536.4.202 states that overload protection shall not be solely based on the use of diversity factors of the downstream circuits.

536.4.3.2 states that rccb’s and switches to BSEN 60947-3 do not provide protection against overload therefore they shall be protected by an over current protective device
 
The key sentence is that we can’t rely solely upon diversity of the final circuits and that manufacturers instructions are followed.
Given that Hager have jumped in and defaulted to using 100amp devices , my interpretation is that we must ensure the rccb is protected by not relying on the diversity factor
 
Are you telling me that say 3X 32A breakers plus a few 6A for ligting are going to exceed the 100A mains switch not to mention the absolute max of a 100A BS1361 type 2 incoming fuse ?
 
Are you telling me that say 3X 32A breakers plus a few 6A for ligting are going to exceed the 100A mains switch not to mention the absolute max of a 100A BS1361 type 2 incoming fuse ?
No however Jpel/64 or Beama who are on the panels aren’t they are tell us yes?
As if a domestic installation will ever exceed say 80 amps or even 63 amps depending on size and the likes of heavy loads like showers.
I think the fact the potential could be there to cause overload is the driving factor to the regulation(s)
 
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As I said, we always had to design around a split load board, ie. we divided the circuits up and tried to load split anyway, just the regs never explicitly said we should, although this was common? sense to anyone sparking professionally.
 
Historically we have used diversity of the final circuits to ensure that the rccb is not overloaded.
Now it seems we can not rely solely upon diversity of the final circuits downstream of the rccb and overload protection must be ensured by other means like having the upfront ocpd rated lower or equal to the rccb and main switch or ensure that the final circuits added are not greater than the rccb and ensuing manufacturers instructions are complied with.
I know with Hager they have taken the approach of fitting 2x 100amp rccb’s (Also now type A) in their dual rcd consumer units so obviously they intend to ensure that their rccb’s are not overloaded and have defaulted to use 100amp devices.
This is certainly the guidance also given by my companies scheme provider.

And the correct guidance.
 
The key sentence is that we can’t rely solely upon diversity of the final circuits and that manufacturers instructions are followed.
Given that Hager have jumped in and defaulted to using 100amp devices , my interpretation is that we must ensure the rccb is protected by not relying on the diversity factor

BEAMA, that speak on behalf of all UK manufacturers have stated that diversity cannot be used. So if a CU is being installed to the 18th it needs to either have RCCBs rated as you have stated.
 
Are you telling me that say 3X 32A breakers plus a few 6A for ligting are going to exceed the 100A mains switch not to mention the absolute max of a 100A BS1361 type 2 incoming fuse ?

Using that argument then why bother with OCPDs on lighting circuits? I mean they are never going to be overloaded...
 
Forgetting for a moment the last paragraph in reg 536.4.202 which I will come back to.
That reg still states it is the IB or design current that we should be designing to, which fair enough we always did, at least the better sparkies did.

Now one manufacturer tells us we were all wrong ? it remains to be seen if they all jump on the bandwagon? if they do the that just goes to show that it is just one massive con game.
The same F***ers should have been prosecuted for selling sub-standard CUs in the first place!
 
Might call around the wholesalers tomorrow and see who has a split load consumer unit in stock with 100A RCCB's
 
Why? Where does it state they should be ? When we don’t fit DP or SPSN Mcbs
because if you get a N-E fault this will of course trip the up front SP RCBO device, however by being SP will leave the N-E fault still present.
Now if this was a farm or agricultural install this will also trip the front 300mA RCD required for fire protection, with no means of being to isolate the fault, at least a (SPSN) single pole switched Neutral would Isolate the N-E fault.
This should have been designed in from the get go, even for domestic where a SP RCBO still would leave a N-E fault present.
 
because if you get a N-E fault this will of course trip the up front SP RCBO device, however by being SP will leave the N-E fault still present.
Now if this was a farm or agricultural install this will also trip the front 300mA RCD required for fire protection, with no means of being to isolate the fault, at least a (SPSN) single pole switched Neutral would Isolate the N-E fault.
This should have been designed in from the get go, even for domestic where a SP RCBO still would leave a N-E fault present.


I get this. As I do agricultural work and work in EX environments where it’s all double pole. But we were talking about domestic. I’m not saying it’s not a good idea. What I am saying is you said it should be DP, where does it say it “should “
consider this in an domestic environment, where you have a distribution circuit to a garage supplied with SWA, a neutral fault would go undetected on a MCB
 

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