Garage Wiring 1970s - is this correct?

[CanDoSafely]

Hi, my first post so apologies if it's in the wrong place. I have a 1970 house which has 2 garages, one attached and one detached. Wiring is original 1970s set up, but I have two queries:

The attached garage has a single socket which is wired from its own dedicated 15A fuse in the old style Fuse Box. The garage light is wired from the downstairs 5A lighting circuit, no obvious probs there. Where the 2.5mm enters the garage I'd like to put a RCD on the wall to protect the circuit, can I do that myself?

The detached garage was added back in the 1970s, it also has a single socket. The wiring for this starts at a 30Amp red fuse in the box, presumably they took a supply from the downstairs ring main fuse. This exits the house via attached garage on 2.5mm T&E, then through thick metal conduit disappears underground and reappears in the detached garage (approx 10 metres). Is this correct even for the 70s?, any suggestions bearing in mind limited budget and what would be notifiable here? Thank you.

 

[CortinaV8]

I think the CU addition would be notifiable, as an easy fix why not just fit sockets with an RCD built in, i'm sure people will be along shortly suggesting a board change but if you can't afford it, you can't afford it.

Re the cable in buried conduit, not ideal, but it could be worse, my father in laws detached garaged is supplied by a PVC cable suspended on a wire between the house and garage, has been since 1979 when he bought the house.....

 

[Steve]

i'm sure people will be along shortly suggesting a board change but if you can't afford it, you can't afford it.

What? Usually when people say they cant afford electrical work, its because they have spent (or would rather spend) their money on plasma TVs, sky+HD etc. They can afford it, just need to prioritise better!

 

[CortinaV8]

Prioritise would suggest changing the board was a priority, which it simply isn't, how many houses will still be using old 70's wylex boards and VIR cable in 10 years time, hundred of thousands I would imagine.

 

[ban-all-sheds]

The wiring for this starts at a 30Amp red fuse in the box,...2.5mm T&E...Is this correct even for the 70s?

No - it's never been OK to have 2.5mm² on a 30A fuse.

You need to put a larger cable in or reduce the fuse rating.

 

[CanDoSafely]

i'm sure people will be along shortly suggesting a board change but if you can't afford it, you can't afford it.

What? Usually when people say they cant afford electrical work, its because they have spent (or would rather spend) their money on plasma TVs, sky+HD etc. They can afford it, just need to prioritise better!

Steve thanks but as a pensioner I don't have a particularly modern telly let alone plasma. My main concern is not going bang when I'm using a drill or jigsaw or a transistor radio in my garage and I thought the easiest solution might be to add a couple of RCDs as near as poss to the source. RCD sockets is a good suggestion thanks CortinaV8 (I used to have a Cortina GXL 2.0, twin headlights.... lovely).
My other concern is that a new consumer unit may be unecessary and that an electrician may condemn my existing 1970s garage wiring and the work would snowball.
As for prioritising better then it's food and heat first and using electrical appliances in the garage will have to be prioritised after that, but thanks for your words of wisdom steve.

 

[chapeau]

The wiring for this starts at a 30Amp red fuse in the box,...2.5mm T&E...Is this correct even for the 70s?

No - it's never been OK to have 2.5mm² on a 30A fuse.

You need to put a larger cable in or reduce the fuse rating.

Are you now forbidding the use of 2.5mm2 cable for use in an unfused spur?

 

[chapeau]

Where the 2.5mm enters the garage I'd like to put a RCD on the wall to protect the circuit, can I do that myself?

Very sensible idea of yours. Install one of these

http://www.screwfix.com/prods/83049...eed-_-Electrical Supplies-_-Volex 13A RCD FCU

and leave it at that until you can come back and sort the rest out.

 

[Chri5]

The detached garage was added back in the 1970s, it also has a single socket. The wiring for this starts at a 30Amp red fuse in the box, presumably they took a supply from the downstairs ring main fuse. This exits the house via attached garage on 2.5mm T&E, then through thick metal conduit disappears underground and reappears in the detached garage (approx 10 metres)

The single TE is likely to be a spur off the ring, so somewhere there will be a socket with 3 cables. This needs converted (take cable off spur fit to load side of RCD spur and run supply link back to the socket the spur cable was removed from) on to a fuse spur, so track the cable and consider adding one of these at £25.00 or so:-

Then everything in the detached garage is RCD protected and fused down to 13a- win, win.

The detached has ONLY a single socket, so the load is limited to the fuse rating of the device plugged in..... but people often tee in the lighting, add extra sockets and the TE single run / spur cable isn't designed for the load that (could be) run from it.

As for the other circuit it would be better to keep the RCD back near / adjacent to the board- Why not interrupt the feed there and site a suitable RCD and enclosure there ?

You are inside regs (flame suit time ?) for the spur RCD fit, but the other job needs a cert / registered spark / LABC notification.

Some sparks are good folk and will offer our elders softer costs

Phone around a few.



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[ban-all-sheds]

Are you now forbidding the use of 2.5mm2 cable for use in an unfused spur?

I wouldn't say that I was forbidding it, I don't have those sorts of powers.

Don't forget:

1) The cable is 10m long, and improperly installed.

2) The protective device is a BS 3036.

 

[bongos]

If you just want to protect yourself when using portable equiment without changing any wiring then you could use a RCD plug top adaptor.

 

[sparkwright]

a new consumer unit with rcds would solve all the problems listed and also some not listed.

the detached garage could be put on a separate circuit. and rcd protection on probably all circuits.

in the meantime it would be sensible to use that plug-in rcd as shown by bongos.

 

[Paul_C]

Are you now forbidding the use of 2.5mm2 cable for use in an unfused spur?

I wouldn't say that I was forbidding it, I don't have those sorts of powers.

Don't forget:

1) The cable is 10m long, and improperly installed.

2) The protective device is a BS 3036.

While I'm not at all keen on 2.5 sq. mm spurs from 30/32A rings, they are still permitted by the Regs. today, as they were in the 1970's.

The cable length isn't excessive for voltage drop, considering the maximum design load wouldn't exceed 13A, and the rating enclosed within conduit is still within the permissible limit for 2.5 sq. mm cable.

And again, while personally I'm not keen on T&E run in metallic conduit, there's nothing in the Regs. against it.

 

[ban-all-sheds]

If you can find a manufacturer to say that it's suitable for continuous immersion in water you might be OK, but as you probably can't then it is not suitable for that use and therefore it has been improperly installed. Plus, is the conduit earthed?

As for the fusing, in terms of overload protection, the design load for a socket can't really be anything other than what BS 1363 requires it to be able to support, which is 20A. What's the capacity of 2.5mm², Installation Method D, BS 3036 protection?

In terms of fault protection, did you do an adiabatic calculation?

 

[Gees]

If you can find a manufacturer to say that it's suitable for continuous immersion in water you might be OK, but as you probably can't then it is not suitable for that use and therefore it has been improperly installed. Plus, is the conduit earthed?

As for the fusing, in terms of overload protection, the design load for a socket can't really be anything other than what BS 1363 requires it to be able to support, which is 20A. What's the capacity of 2.5mm², Installation Method D, BS 3036 protection?

In terms of fault protection, did you do an adiabatic calculation?

Did the OP not say the conduit went underground ? Would that not be earthed then?