18th Edition Compliant Consumer Unit

[RutlandFox]

Hello all.

Quick question: Are 17th reg 3rd amendment metal consumer units compliant with 18th edition regs?

eg Hager VML716RKO

Many thanks (Newbie)

 

[Nigel]

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.

 

[Nigel]

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.

 

[Nigel]

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...

 

[spark 68]

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!

 

[spark 68]

Please tell me where in reg 536.4.202 it says diversity cannot be used ?

 

[spark 68]

And another thing as of 17th AMD 3 the 200 regs was only a UK reg, so much for harmonisation, a big FU to the IEC and CENELEC

 

[jamie-spark]

Oh I don't disagree, a full RCBO board is always nice to have if the customer will go for it, however they should always have been DP, or at least SPSN from the get go for obvious reasons.

Why? Where does it state they should be ? When we don’t fit DP or SPSN Mcbs

 

[mattg4321]

Might call around the wholesalers tomorrow and see who has a split load consumer unit in stock with 100A RCCB's

 

[spark 68]

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.

 

[jamie-spark]

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

 

[spark 68]

It should be at least SPSN, if not DP which is what I originally said, because leaving a N-E fault present is short sighted in my opinion, which is what the vast majority of RCBOs do.

 

[jamie-spark]

It’s all very well if the circuit requires RCD protection , if it doesn’t as stated above a N-E fault would still go undetected, should we be installing sub main supplies in SWA with rcd protection in case there is a N-E fault. Think of the distription due to discrimination this would inflict

 

[spark 68]

I did not say that all, I suggest you re- read what I actually said,
your last post was pretty much incomprehensible

 

[jamie-spark]

I did not say you said that either , I suggest you re-read my post. What is incomprehensible about it and I will try to elaborate for you.

What you are saying is that all RCBO’s (in your opinion and not “should be “ Double pole . What I am trying putting across ,is why do you feel this should only be limited to RCD protected circuits . N-E faults would go undetected on most other circuits where RCD protection is not required

 

[jamie-spark]

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.

It would be ---- poor design to have a upfront 300mA rcd with a SP rcbo down stream . I totally agree