That's exactly what the electrician proposes as he phoned me to ask the size of the existing CU and if there was any space at the side.
Two consumer units, okay or not?
- Thread starter andyfr
- Start date
That's exactly what the electrician proposes as he phoned me to ask the size of the existing CU and if there was any space at the side.
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Then you would have a 25mm² (round) tail and the (flat?) live feed to the RCD both crammed into the bottom of a BS EN60947-3 switch.
I am not sure they are really designed to do that. When you get to large conductors, one per terminal is the rule. That is why they invented Henley blocks.
I am not sure they are really designed to do that. When you get to large conductors, one per terminal is the rule. That is why they invented Henley blocks.
FFS any electrical wholesale outlet can supply any CU config with 72 hours lead time.
Sounds like he either doesn't want to 'touch' the existing CU or he has a CU spare and intends to use that.
You will pay him, so demand he supplies a single whole house CU !
Sounds like he either doesn't want to 'touch' the existing CU or he has a CU spare and intends to use that.
You will pay him, so demand he supplies a single whole house CU !
From Hager technical:
Dear Sir,
An extra neutral link can be supplied from the load side of the
main switch to feed this extra bar or as you say run the existing neutrals
from this bar to the supply side of each RCCB
They are referring to a 3rd cable to feed a 3rd neutral bar.
Ok so they're talking about tri-rated internal CU flexible cables, not 'tails but presumably if the terminal is large enough and done up tight enough and all cables are secure then it's not a problem?
However having 2 identical CU's side-by-side it could be confusing for the user that one big red switch only switched off that board whereas the other one switches off both boards. Obviously the real Main Switch should be labeled but could easily still be confusing.
To the OP - Order a 12-way from Screwfix, pay the extra delivery and be done with it? Inverness might be pretty remote from the main urban centres but it's hardly a backwater, I find it hard to believe that there are no wholesalers who have a 'board big enough. Also a good spark would have checked out how much space you have in your CU cupboard when doing the initial survey.
Dear Sir,
An extra neutral link can be supplied from the load side of the
main switch to feed this extra bar or as you say run the existing neutrals
from this bar to the supply side of each RCCB
They are referring to a 3rd cable to feed a 3rd neutral bar.
Ok so they're talking about tri-rated internal CU flexible cables, not 'tails but presumably if the terminal is large enough and done up tight enough and all cables are secure then it's not a problem?
However having 2 identical CU's side-by-side it could be confusing for the user that one big red switch only switched off that board whereas the other one switches off both boards. Obviously the real Main Switch should be labeled but could easily still be confusing.
To the OP - Order a 12-way from Screwfix, pay the extra delivery and be done with it? Inverness might be pretty remote from the main urban centres but it's hardly a backwater, I find it hard to believe that there are no wholesalers who have a 'board big enough. Also a good spark would have checked out how much space you have in your CU cupboard when doing the initial survey.
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I think he forgot about it as it's been a few months since we started work on the extension. They were supposed to come today, snowed in so has been postponed, and he rang last night. As it's going to be a while before I can arrange for them to come I will ask for a 12 way.
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OK it says:- 537.1.4 A main linked switch or linked circuit-breaker shall be provided as near as practicable to the origin of every installation as a means of switching the supply on load and as a means of isolation.
A main switch intended for operation by ordinary persons, e.g. of a household or similar installation. shall interrupt both live conductors of a single-phase supply.
But in real terms two switches will do same job and the supply authority have to provide an isolator anyway as one is not allowed to work on live equipment so if the supply authority do their job right there is no need for separate isolator.
OK I know the supply authorities don't do what they should but it really is up to them not us to provide the first isolator.
A main switch intended for operation by ordinary persons, e.g. of a household or similar installation. shall interrupt both live conductors of a single-phase supply.
But in real terms two switches will do same job and the supply authority have to provide an isolator anyway as one is not allowed to work on live equipment so if the supply authority do their job right there is no need for separate isolator.
OK I know the supply authorities don't do what they should but it really is up to them not us to provide the first isolator.
As said before sounds like he has a spare cu he wants rid of,
http://www.yell.com/ucs/UcsSearchAc...leSeed=60814284&M=0&autocomplete=kw&x=17&y=17
from the link above ring round a few places to see who has 12 way cu in stock, think most will
http://www.yell.com/ucs/UcsSearchAc...leSeed=60814284&M=0&autocomplete=kw&x=17&y=17
from the link above ring round a few places to see who has 12 way cu in stock, think most will
Have a look at EDQ13 and EDA13 from the ESC:
EDQ13
If a dwelling has an existing consumer unit with an integral main switch, and an electric shower is connected by means of a second consumer unit with an integral main switch, is another 'main switch' required to isolate both consumer units simultaneously?
EDA13
Regulation 537.1.4 requires a main linked switch or linked circuit-breaker to be provided as near as practicable to the origin of every installation as a means of switching the supply on load and as a means of isolation.
However, it is permitted for a dwelling to have more than one electrical installation. Therefore a further 'main switch' is not required to isolate both consumer units.
Regulation 537.2.2.6 requires each device used for isolation to be clearly identified by position or durable marking to indicate the installation it isolates.
Pretty much the same thinking as the ECA when I called technical a while back about a similar situation.
EDQ13
If a dwelling has an existing consumer unit with an integral main switch, and an electric shower is connected by means of a second consumer unit with an integral main switch, is another 'main switch' required to isolate both consumer units simultaneously?
EDA13
Regulation 537.1.4 requires a main linked switch or linked circuit-breaker to be provided as near as practicable to the origin of every installation as a means of switching the supply on load and as a means of isolation.
However, it is permitted for a dwelling to have more than one electrical installation. Therefore a further 'main switch' is not required to isolate both consumer units.
Regulation 537.2.2.6 requires each device used for isolation to be clearly identified by position or durable marking to indicate the installation it isolates.
Pretty much the same thinking as the ECA when I called technical a while back about a similar situation.
get a 15 for future additions..you never know..
H
holmslaw
..
An installation in this case would be a number of final circuits from a consumer unit. The main switch in that consumer unit would be at the origin and labelled as such.
Two consumer units supplied independently from a 100A henley block could well be seen as two installations, exactly in the way the ECS and the ECA (to my experience) see it.
I think maybe another reason for not managing to get a 12 way at short notice is that it needs to be an MEM unit. This is so that all our existing MCBs can be reused. I am going to see if I can find one in stock myself, what model MEM would be the one to get?
MCBs cost a couple of quid each, so it isn't worth buying any particular brand in order to reuse what you already have. If he's not installing a dual RCD unit then he'll need to use at least some RCBOs as well, so your existing MCBs would be of no use anyway in that situation.
Whether you decide on one large cu or two smaller units, ensure you have plenty of spare ways for future additional circuits.
With two new smaller cu's you may have the advantage of having four RCDs to spread over the various circuits, eliminating the expense of RCBOs.
Tho RCBOs are more desirable...
With two new smaller cu's you may have the advantage of having four RCDs to spread over the various circuits, eliminating the expense of RCBOs.
Tho RCBOs are more desirable...
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