Spur to ring main


Postby doozer » Sun Oct 18, 2009 8:44 pm

Hi all,

So, today I 'broke in to' the ring main in my garage and fitted a 30amp junction box, then from this have run a spur for a double socket (for a fridge/freezer and a not-continuously-used washing machine).

So;

30amp JB (one of those brown round ones), fixed securely.
2.5mm twin + Earth (earth is sheathed) - I am pretty sure it's 2.5mm, it is the same as the ring cable, about 1cm wide in total.
Spur length approx 3m
Cable down the wall is in plastic conduit.
Plastic wall mounted socket.

Everything works fine.

...Does all this sound OK? Am I missing anything?

Cheers.
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Postby ericmark » Mon Oct 19, 2009 9:46 am

Sounds OK but question has to be:-
1) How do you know it is a ring main? Did you test to see the ring was complete?
2) What was the earth loop impedance?
3) Was it under or over 3 meters as 3 meters is the maximum length of cable permitted when going from one current carrying capacity to another (32A to 20A) before the current limiting device (Fuse in plug) is 3 meters.

When filling in your minor works certificate you will need to know.
Type of earthing system (TN-C-S etc)
Method of fault protection (EEBADS etc OK new name now but near enough!)
Protective device (B32 MCB etc)
Insulation resistance Line/Neutral Line/Earth and Neutral Earth
Earth fault loop impedance
Polarity
RCD operation current and time.

I realise many DIY people will not test and inspect but that does not make it right. For me or anyone else to just say yes that’s grand without pointing out all the tests should be done would be wrong.

I was banned from the site for not telling people about the dangers, what always worries me with ring mains is where it was not a ring main but a centre spur where someone has taken a spur from a spur. Never assume always test. Even I have made mistakes and it is important to test then any errors are found.
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Postby steve the plumber » Mon Oct 19, 2009 12:55 pm

[quote="doozer"]Hi all,

So, today I 'broke in to' the ring main in my garage and fitted a 30amp junction box, then from this have run a spur for a double socket (for a fridge/freezer and a not-continuously-used washing machine).

So;

30amp JB (one of those brown round ones), fixed securely.
2.5mm twin + Earth (earth is sheathed) - I am pretty sure it's 2.5mm, it is the same as the ring cable, about 1cm wide in total.
Spur length approx 3m
Cable down the wall is in plastic conduit.
Plastic wall mounted socket.

Everything works fine.

...Does all this sound OK? Am I missing anything?

Cheers.[/quote]

You are joking aren't you???

You would have been safer to install a new circuit. I would turn this off immediately, and get a sparky to do it properly.
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Postby doozer » Tue Oct 20, 2009 11:45 am

thanks for the replies.

I'll get an electrician to check it's all ok.

I guess the thing is...is that there was just a 5m extension lead plugged into the nearest plug, with 2 sockets on the end that powered the fridge/wash mach. All this seemed fine for the past 2 years.

I thought that wasn't very good, and 'spuring off the ring' would be better.

I assumed it was ring, as the cable goes round the room (it's a garage and the cables are clipped to the rafters), also, the fuse says...'garage ring'.


Anyway, as advised, I'll get it checked out.

Thanks
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Postby sparx » Tue Oct 20, 2009 5:58 pm

Hi, taking on board all Ericmark has said, & leaving aside for a moment comments from steve the PLUMBER; what you have done can only be an improvement on trailing multiway extention lead.
My comment would be that to comply with current regs. if the circuit is not already RCD protected, as soon as you alter it you must fit such protection.
We are all assuming the garage is integral with the house, if detached then LABuilding Control Part-P comes into play as well See Projects section.
Regards SPARX,

(BTW Welcome back Eric)
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