its not a proper ring!

[stevie2011]

In a domestic, none of the 3 ring mains comply with the 0.05 difference between sockets, some readings varied drastically, anyway I'm sure they're not proper rings, rewiring them is not an option. Could I just fuse it down to a 20amp breaker and leave both tails in the MCB or would I have to leave one out and put it in connector block?

I think ring mains shouldn't be allowed in places that don't get regular periodic inspections, (such as domestic) but anyway thoughts?

 

[tony mc]

When your testing what are the readings and how far out are they?

 

[stevie2011]

readings between .68 and .134 on r1 and r2 downstairs. which was my main worry. End to end LL - 1 NN 1.05 EE 2.12

 

[tony mc]

Is you final ring cable 2.5/1.5 or 2.5/1.00 ?

When testing are you sure you have the correct legs cross connected in the figure of eight.When testing at socket outlets without removing the socket you can get high readings.
If you are going to reduce the mcb down to a 20 A you will have to split the ring at the CU and somewhere on the ring to make two radial circuits.
If you leave both legs in the same mcb you will have one mcb covering 2 radial circuits only allowing a max of 4600w.
So you will have to see what the demand for the circuits are going to be.
I would trace the fault and leave the CCT as final ring circuit.

 

[PC Electrics]

Worn contacts in sockets?
Worn socket switches?
loose connections somewhere?
mix of cpc sizes?
long 'spurs'?

Have you done any fault finding yet?

 

[Octopus]

readings between .68 and .134 on r1 and r2 downstairs. which was my main worry. End to end LL - 1 NN 1.05 EE 2.12

Your end to end figures makes me think you've got 2.5/1.0 cable

Could your other readings be down to spurs?

 

[stevie2011]

the sockets are old, i really should have taken them off and checked it from the inside, I was going through it a bit quickly since I'm basically just doing it as a favour for a mate as I'm out of work and got nothing better to do. I going to go back anyway and I'll thoroughly inspect it next time and try and trace whats going on. The upstairs and the kitchen I can easily believe its just the sockets from what I was getting and the state of the sockets but I'll have a closer look. Just really wanted to know if it came down to it what would be the non rewire option. thanks tony, I doubt it'd get up to 4600w, but hey who knows.

Edit:
the ones with high readings i did open up and they weren't spurs atleast they shouldn't be having in and out, but when i look again maybe i'll find a strange end of line. probably should have tested them again from the inside while I had the ones that i had open, but this time i didn't. I think you might be correct about 2.5 / 1.0 cable thats unusual, when was that ever allowed? Now it has to be 2.5/1.5 or 1.5 / 1.0 if it has been fused down. I havn't managed to get around to fault finding yet. Just had a quick look really.

 

[stevie2011]

IR test just did off the busbar got like 8 megaohms for the circuits on the board. After reading these posts and thinking about what i saw, It could just be a combination of faulty sockets (as i was testing off the sockets) and change in CPC sizes, as theres stranded AND solid core cable in the circuit same for the others and i think theres 2.5 / 1.5 and 2.5 / 1.0. even having it cross connected at the board, testing at different socket outlets a change in cpc size could affect the readings right?

 

[stevie2011]

well I did the cross connection to opposite legs (R1 to R2), tested Zs which varied aswell, stupidly didn't write down anything except the highest which was .50 oddly. Just baffled now thinking if its just because of cpc changing size how will I be able to prove its a proper ring without being able to trace the cable, or am I over thinking it now? Man I just want to go back and do a fresh install where I don't have to fault find unless some idiot has pinched a cable on a trunking buckle.

 

[B6 7BU]

I think ring mains shouldn't be allowed in places that don't get regular periodic inspections, (such as domestic) but anyway thoughts?

Take a look at this

[video=youtube;l5Mmz1OnCR8]http://www.youtube.com/watch?v=l5Mmz1OnCR8[/video]

 

[Engineer54]

Take a look at this

[video=youtube;l5Mmz1OnCR8]http://www.youtube.com/watch?v=l5Mmz1OnCR8[/video]

Award Winning Training Provider, Think that about says it ALL!!

 

[SPARTYKUS]

Or just one MCB per socket run in 6mm, radial. If you'll indulge me

 

[telectrix]

in a 40 way CU no doubt.

 

[stevie2011]

hahaha, I love that video. "but all the sockets would still work"

and "I have this tester, if you get 3 green lights it works"

hahahaha love it.

 

[Engineer54]

Ring Finals for the main house sockets/radials in 4mm for kitchens and 2.5mm garages/outhouses. Reduce the in between times for periodics on domestic. The idea with rings was to spread the load evenly (although this is sometimes abused) but the disadvantage is if there is a break in the cable it will still be energised both sides of the break

Why are you trying to label and restrict uses for final circuits here?? You design and install a final circuit as to the requirement of the installation, and for no other reason. There are up sides and down sides to both ring and radial final circuits.

This old chestnut about breaks in ring finals, is what many highlight, in reality they are about as common as a radial losing it's CPC along the line, ...Rare!!!