Main swich between tails

[peteelecs]

Hi
could someone clarify for me please if I use a Henley block to add a shower unit next to my cu is it compulsory to put a 100A main switch between the meter and the Henley block?

 

[sparks1234]

Well, I am writing it here taking it straight from black and white and also from a phone call from the ECA a week or so ago so thats it as far as I can see, for £17 quid is it worth the risk?? not for me.

 

[Yooj]

I concur with JasonS and Des56 that there is no requirement in BS7671 for a single isolator covering an individual dwelling irrespective of the quantity of installations in said dwelling.

All the regs state is that each installation shall have a suitable isolator disconnecting all live conductors...therefore to Des56's point, adding an additional CCU just means that this is deemed a new installation and thus the main switch within the new CCU is the isolator which satisfies the regs, and therefore no need to add a further single isolator covering the whole dwelling/building.

I would say though that there would be a need to have a safety label/sign indicating multiple supply sources (537.1.6)

Look at Regs 537.1.3 to 537.1.6. A bit convoluted, arguably, the semantics of 'Installation' can cloud the issue here.

In terms of NICEIC/ELECSA/ECA/NAPIT perspectives...they are just perspectives based upon an interpretation of the regs, and therefore open to other viewpoints.

In summary, I would say that there is no need as per BS7671 to install a single isolator covering an entire dwelling/building, but there is no real harm either by doing so assuming the cost can be absorbed in the job...and to be fair, by adding one, it makes future ammendments/additions easier since you do not need to disturb the meter/cut-out fuse seals.

Yooj

 

[SirKit Breaker]

The installation work YOU do (eg sep cu) must have a single point of isolation, which would be the main switch for the CU that you have just installed.

Therefore, you would then have 2 installations in one building, with a main switch for each installation.

No need for a separate isolator.

Thats what i was trying to say, if it is a requirement to fit a DP isolator as stated in earlier posts, then every
cu in the land needs one fitting.

 

[peteelecs]

Didnt think my question would cause a bit of an argument but thankyou to all for replying

 

[sparks1234]

Didnt think my question would cause a bit of an argument but thankyou to all for replying

Pete.

I think it is up to you to make your own mind up on this, this argument has raged long and hard on this and another thread.
Read the regs and make up your own mind is the thing to do.

Good luck

 

[Spudnik]

Gotta love BS7671!!!!!!!

 

[Sintra]

I am going to ask a hypothetical question now.

Supposing the installation was installed as previously quoted with 2 CU's from a henley block without an additional main switch.

You are called in 10 years time to do a PIR on the installation.

1. Do you do 2 PIR's as some members say this is 2 installations.

or

2. Give a code for the installation for not having a main switch.

 

[SirKit Breaker]

Didnt think my question would cause a bit of an argument but thankyou to all for replying

Its always good to hear other peoples opinions and takes on the regs, at least on this forum there isnt anybody who has their heads up their a***s and assume that they know it all and try to belittle people.

 

[pennywise]

Surely you would only have to put the second board on a separate continuation sheet as there is only one supply into the building correct me if I'm wrong.

 

[Sintra]

Surely you would only have to put the second board on a separate continuation sheet as there is only one supply into the building correct me if I'm wrong.

Yes that's what I would think a PIR with a continuation sheet which makes it 1 installation so therefore you should have 1 main switch.

 

[Yooj]

It is a very good question, and it would have to be two PIRs, since the PIR paperwork only allows you to write details of a single main switch...therefore it would need to PIRs.

Would have to be the same even if there were a single isolator for both CCUs.

Yooj

Hmmm...just thinking about it though, you would get away with detailing the isolator as the main switch...Decisions, decisions.

Yooj

Ok...thought about it a bit...Two PIRs for no single isolator, as there are effectively two main switches, and thus two installations; one PIR when there is a single isolator for both CCUs as it can be classed as a single installation and use a continuation for the other CCU.

 

[pennywise]

Could you not just designate one board DB1 on the original PIR sheet and on the continuation sheet designate the second as DB2 and then use the first line on the sheet for the Main switch BS number, rating etc their are already spaces available for information like where it's feed from on the schedule and the nature of the source of supply.

 

[Yooj]

To be quite honest...let's say the second CCU was just a garage unit with two circuits for arguments sake - no single isolator...I have no problems with doing this on a continuation sheet.

However, let's say it is a big dwelling, with two similar sized CCUs feeding separate wings of the dwelling, all fed via a single supply...I would do two discrete PIRs for this as opposed to a continuation sheet.

Yooj

 

[pennywise]

Think I may ring the tech line at the NIC just for interest sake, we shall see what the grand arbiters of the electrical industry think tomorrow. If a PIR is needed for every CU attached to a Henley with a separate main switch or isolator , 5 sheets of paperwork for one two way shower unit will look like Bureaucracy gone mad.

 

[Yooj]

As I said before though...it is just their opinion/interpretation of the big red book.

Let us know what they say though.

Yooj