RCD as a main isolation switch

[STI]

I have been asked to move a couple of socket outlets in a kitchen and add a new one. When I checked the CU for RCD, earthing etc i noticed that a RCD isolation switch has been fitted (30ma 60A) between the supply and the CU. I think the set up was likely to have been a TT system which at some point appears to be upgraded to a TNS. Its a victorian terrace house.

There is no RCD protection in the CU.

I realise this set up is not up to latest standards and is a single point of failure but does it satisfy the need for RCD protection for bathroom/kitchen/sockets. Ive read the special location regs 701.411.3.3 and 415.1.1, 531.2.4 and 314.1 iv and its seems to comply . My question is would a BCO refuse to sign off even if all the tests passed.

 

[Spark123]

Technically it won't comply as you have the single point of failure hence doesn't comply with section 314 of the regs.
Wether or not it will pass will depend on the inspector.

 

[1john]

Unlikely that a TT would be upgraded to a TNS, almost always upgraded to a TN-C-S. This arrangment was quite common in days gone by, infact until recently my LA would spec a CU with an RCD upfront on all works

 

[STI]

Yes i was going to call them today but missed the actual inspectors time when they are in. Interestingly when i spoke to the person who answered the phone and just asked them what they wanted from me the reply was just send in your test results and if ok we will issue the completion order, no inspection needed.

 

[STI]

Unlikely that a TT would be upgraded to a TNS, almost always upgraded to a TN-C-S. This arrangment was quite common in days gone by, infact until recently my LA would spec a CU with an RCD upfront on all works

Yes i was guessing about the upgrade i just havent come across a RCD isolation switch being put in other than in a TT. In this place the main earth is definitely to the collar.

 

[1john]

Yeah, I expect it to be a lead sheathed cable, more than likely original. I presume you haven't been doing the job long, it's a common occurance to have an RCD upfront of an old wooden wylex, seemingly put in as an upgrade.

 

[STI]

Yeah, I expect it to be a lead sheathed cable, more than likely original. I presume you haven't been doing the job long, it's a common occurance to have an RCD upfront of an old wooden wylex, seemingly put in as an upgrade.

Yeah not too long and until now nice 1970 bungalows which have all been upgraded to latest wiring (not by me unfortunately) The CU at this place is a MEM, 60898 MCBs but no stickers as to its installation time.

I will speak to the BCO and see if they will accept it as for the work to be done or whether this new socket is going to cost a lot more than expected.

Thanks

 

[1john]

Just list it as a departure from the regs on the cert, inform the home owner of the risks of an RCD upfront, they will know about it already as it's bound to have tripped.

 

[ericmark]

The question is does it regularly trip. If not then it complies. The book does not say you must have two RCD's and most caravans and boats only have a single RCD.

What it says is "(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced
by equipment in normal operation." and unless it trips on regular basis it passes this requirement.

Yes it also says "(i) avoid hazards and minimize inconvenience in the event of a fault.
(iii) take account of danger that may arise from the failure of a single circuit such as a lighting circuit."

But having a single suppliers fuse would also cause dangers if it was to blow so where lighting is a problem it should be battery backed rather than using two RCD's.
As to minimize inconvenience in the event of a fault. If we follow to letter then even two RCD's would not be enough we would need RCBO's on all circuits.
Unlike new installations where we don't have a clue what items the occupier may use so no idea as to if it will likely trip with this house you have a history so "By enquiry" you can easy find if it complies.

 

[STI]

Thanks everyone for the replies. If common sense and test results prevail then it should be acceptable but i will talk to the BCO as i dont want to do the work and then find its refused by them. I'll post back their response.

 

[STI]

Yep BCO said as long as tests are passed then its ok. Seems like common sense and maybe a heavy workload are prevailing

 

[ban-all-sheds]

I have been asked to move a couple of socket outlets in a kitchen and add a new one.

Wouldn't it have been cheaper for them to use a registered electrician?

 

[STI]

Nope mates rates and more experience for me Plus there is other work needed that is not notifiable so everyones happy.

As a general point ive found that once a job requires more that 5 pieces of work doing the £70 fee soon gets "lost" . I might not make as much profit on the job but thats my choice.

 

[riveralt]

Nope mates rates and more experience for me Plus there is other work needed that is not notifiable so everyones happy.

As a general point ive found that once a job requires more that 5 pieces of work doing the £70 fee soon gets "lost" . I might not make as much profit on the job but thats my choice.

I know its £75 in Birmingham City but that is still cheap - looking around one of the highest I have seen is £312 in Sefton Merseyside
No wonder people ignore Part P!

 

[ban-all-sheds]

As a general point ive found that once a job requires more that 5 pieces of work doing the £70 fee soon gets "lost" .

8-9 jobs/year makes it cheaper for you to register.

I might not make as much profit on the job but thats my choice.

A sensible choice?