Cable to garage Ask questions and find answers to many subjects relating to electrics and electrical work

[Andy F]

Hi, our garage currently has a small shielded metal cable ( Mineral Insulated ??? ) with a gland at each end, This i think is pre 1960's.
How can I find out what it's current carrying capacity is? I would like to use it for putting a light and a twin socket in the garage, I don't want to replace it wit SWA or similar as it's laid under concrete and there's no real route for SWA.

Thanks
Andy

[sparx]

sorry for late reply, only just found forum,
smallest MI cable made was 1.0mm, but mainly 1.5 min used, current rating of 1mm =18.5A, 1.5 =23A
so safest way unless the cable gland has other info on it ie 2L2.5 which means 2.5 mm 2core light duty etc play safe and feed from house via RCD fused spur with 13A fuse fitted then can have double socket plus light via a local fused spur with 5A fuse as switch.BUT this is all part p work which needs a sparks to do, sorry
SPARX

[Andy F]

Thanks Sparx, this is the pic of the cable, how does the earth work on it?

http://i178.photobucket.com/albums/w254 ... geelec.jpg

[sparx]

the threaded gland you can see with the wires exiting was meant to fit into a metal enclosure with a locknut inside, this would then pickup the earth from the cables copper sheath, which has a larger cross-sect. area than the core wires.
there is a plumbing style olive fitted onto the cable between the hex. nuts to ensure good connection to sheath.
The copper clip in use is a common way of making up for losing the earth when changing from metal to plastic enclosure, the cable may have plastic outer sheath over copper. scaling 20mm/ 3/4 inch gland makes me think you may have a 2.5mm cable, rated at 31Amps.
cant see where red&black go to but they need to be protected better,,,,,,sparx

[Andy F]

Nice one Sparx, Thanks for the info. :D

[Andy F]

Sparx, one more quick question if I may?
The red and black cables come up and are wired into a plug, the plug is then into a socket which is fed of a dedicated mcb. Would it be better to get a new gland and have it running to a metal junction box ( With a blanking cover ) where it can be earthed to the box via the gland, and then use the earth of the 2.5mm from the mcb to finish the earth to the consumer unit? If that makes sense. And the same at the garage end but going into a Builders/garage consumer unit.
Thanks

[sparx]

andy
I didn't realise your photo was supply end but no matter,
BE VERY CAREFUL about bending cores they are hard copper which WILL break!!!!
do not attempt to do any thing to gland end seals, once disturbed your in trouble, special pot seals etc.
Your idea is good but doubt you will get 1inch locknut 25mm won't go on, adapters where available but doubt they still are, your pyro will go on for ever if not played with too much so suggest getting a box, cut a slot to allow cable end complete into it, connect red/black/earth to 30A chock block then connect to cable 'currently' feeding dedicated socket.
garage unit on other end with RCD/mcb's as suggested, remember garage is part p notifiable so you might want to befriend a registered sparky!

[Andy F]

Top advice as allways mate. Is that earth ok to use tho?

[sparx]

as long as it's tight and at least 1/2 size of main wires it should be ok but I always use crimps on cable then bolt to clamp