RCD PROTECTION OF REMOTE SPUR SUPPLY

[TedBrisket]

We have a spur taken off the kitchen ring main, extending to the adjacent store room at the back of the house then on via a short catenary to a garage.
In each location there is a single power socket and switched light.
The wiring needs tidying up and bring up to date etc.

This whole circuit comes from the house RCD protected supply and with a MCB of 32 amps. Is this RCD which is located at the front of the house able to protect the
remote spur wiring or is extra similar protection required?
I ask because "Garage Consumer Units" with RCD incorporated are available and could be located in either location if necessary.
If not needed could a simple 4 way consumer unit each with MCBs of 16 and 6 amp be installed in both store and garage for power and lighting. Very little power
is needed. Just the lawn mower and various electric tools!

Thanks

 

[RF Lighting]

When you say a spur do you mean a direct connection into the kitchen ring circuit, or is there a fused connection unit fed from the kitchen ring which supplies this feed to your store room and garage?

What size is the wiring which supplies your store room and garage?

What makes you think you suddenly need an additional consumer unit for the supply to your store room and garage?

 

[TedBrisket]

The spur is a diirect wired in connection.

In the store the lighting cct is taken off the main cable with no extra isolation or fusing!

In the garage there is an old fuse box with 15 amp and 5 amp wired fuse holders
None of this is good. Bad actually!

The spur wire size is 2.5mm T & E

It would seem logical to put separate small consumer units in each location so each specific area light and socket is protected to the correct value.

I was asking if an additional RCD in either store or garage is necessary and would provide any additional protection considering they are a bit of a way from the main house RCD.

 

[RF Lighting]

Right well first things first.

What you have currently is not acceptable, and putting extra fuse boxes in is only going to make it worse.

You are only allowed to feed ONE point via an unfused spur from a ring final circuit.

From the sounds of it, what you have now is just one big mess, and it's going to be easier to replace the whole lot rather than trying to re-work what's already there.

Is the cable attatched to the catenary wire to the garage just standard twin and earth too?

 

[TedBrisket]

Thanks again for the prompy reply.
I have had the feeling for a while that this whole section has to be rewired. For some reason this spur and attachments have been forgotten. The main house is fine.

Will have a look at the catenary cabling in the next day or so and let you know.
Is there some spec for this type of wiring?

Ted

 

[ericmark]

There are a host of regulations covering these locations and wiring conventions. This includes the type of earthing. You have not stated what type the house is TT or TN? or distances? and if there are extraneous conductive parts? all which will have a bearing on what is required.

Even as an electrician the earthing methods required are not always at first apparent. As a result I would not want to advise without seeing what is there. So easy to miss something vital which changes what is required.

If the house and outbuildings are on the same earthing system then no need for extra 30ma RCD's however not all RCD's are 30ma again you don't say what you have.

Twin and earth cable is not designed for outside and spurs from spurs without using a FCU when supplied from a 32A fuse/MCB is clearly against the regulations.

However with the Part P rules to rip out and replace as a DIY job is also expensive due to LABC charges and first step I would say is get a quote for an upgrade as if may be cheaper to get a scheme member electrician to do the work than to DIY.

There are a number of cables which can be used outside often steel wired armoured SWA is the answer.

 

[TedBrisket]

Thanks to both for helpful comments.
Problem has been resolved today with a visit from our electrical installer.
The plan now is to disconnect the spur from the identified ring main connection point. run a new radial cable from a spare 16a MCB slot in the house CU and tidy up / replace as necessary all the existing cables and boxes etc in garage and outhouse. This will include recabling the catenary route to required spec.