So many Spurs it's like the wild west

[ericmark]

It would seem you have not understood what I said about spur or ring. Unless you know the PSCC is above 244 amp at the centre of the ring, then you don't know if extending the ring would be permitted.

 

[motorbiking]

I understood, but was coming from a different angle. If I ask can we have abc and they so no because of xyz then u can be confident it's a considered response based on some testing/investigation. however if they answer we usually do 123 not abc because it's quicker/easier/how we do things then it's not.

at the end of the day some of the spured sockets were installed as ring by another qualified electrician but needed to be temporarily cut for building work. it's these that I asked to have back on ring. to be fair when I've asked, they've done it. Hence why I asked if there was a specific reason for Spurs now.

and you've answered that so thank you.

 

[securespark]

I have wired a warehouse using all spurs from the ring, it had a 6mm² ring with a junction box above every socket with a 2.5mm² cables down to the socket, it was done this way to reduce the cable used in the ring and so keep the earth loop impedance within the required limits.

Surely a ring final can only have as many spurs as points on the ring final?

 

[DetlefSchmitz]

Surely a ring final can only have as many spurs as points on the ring final?

Quote the regulation!

 

[EFLImpudence]

I have wired a warehouse using all spurs from the ring, it had a 6mm² ring with a junction box above every socket with a 2.5mm² cables down to the socket, it was done this way to reduce the cable used in the ring and so keep the earth loop impedance within the required limits.

Surely a ring final can only have as many spurs as points on the ring final?

Not sure what you are getting at - you can always make more points.

 

[EFLImpudence]

Surely a ring final can only have as many spurs as points on the ring final?

Quote the regulation!

He didn't say sockets.

 

[DetlefSchmitz]

Surely a ring final can only have as many spurs as points on the ring final?

Quote the regulation!

He didn't say sockets.

...and...

 

[EFLImpudence]

I thought you were referring to the oft quoted cobblers "You can't have more spurred sockets than there are sockets on the ring".

About which supposed regulation were you asking then?

 

[securespark]

That was it.

Oft-quoted cobblers maybe, but it's in the OSG, as is "unfused spur lengths should not exceed 1/8 the cable length from the spur to the furthest point of the ring."

 

[securespark]

Surely a ring final can only have as many spurs as points on the ring final?

Quote the regulation!

A38, 14th Ed.??

For ring final sub-circuits...the total number of spurs shall not exceed the total number of socket outlets and stationary appliances connected directly in the ring.

OK, it's not a reg, but in the OSG it states something very similar:

...the number of non-fused spurs is not to exceed the total number of socket outlets and items of stationary equipment connected directly in the circuit.

 

[EFLImpudence]

Not arguing with you but the rules.


No limit to fused spurs? What's the difference?

Anyway, in the OSG doesn't count if not in 7671.

Is this a remnant, which should have been removed, which comes from when there were, for no reason, a stated limit to the number of sockets/points allowed on a ring final?

If you want to comply with the OSG today then put more sockets on the ring.
Does it seem sensible when that is the remedy?


I have an idea.
Let's get together the authors of the innumerable guides and approved documents and the authors of BS7671 so that they can all draft, edit and get right first time the eighteenth edition so that that it will be all that is necessary.

 

[securespark]

I agree there is a lot of stuff in the OSG which are remnants from the 14th.

Just comparing the wording of the 14th Ed reg with the snippet from today's OSG will show you that.

Also in the OSG is the 2m rule about cooker switches.

 

[EFLImpudence]

It's not good enough is it?

Registered electricians have to buy and keep buying the OSG for the scheme to accept and keep accepting them.

At one assessment, I said I didn't have the latest as I never looked at it, other than to find mistakes, and thought it was a very poor publication (rubbish). I had to order one online there and then otherwise he would not continue.

 

[ericmark]

I suppose at every junction box we could have put a socket box instead then run the spur from the socket, but since the ring was in the roof space and all the sockets were in the fridge space it would have been rather pointless, they were only there for cleaning, some one had worked out the length of lead on the cleaning tools and given instructions on where the sockets were needed. At +5°C it was unlikely any spur would over heat, and there was no need for sockets in the loft space.

We looked at the size of the fridge it was about 20 foot high and around 100 yards square and with the drops to each socket the volt drop even with 6mm² cable would be too much, it would add around 30 foot at each socket, it does not take rocket science to work out using spurs will reduce the volt drop problem. Yes could have increased to 10mm² instead of 6mm² but then it would still need a junction box next to socket to reduce cable to a size which would fit the socket. I know "Historically, limit of 100 m² has been adopted." but what should one do with a single room which exceeds 100 m²? Anyway when it was done it was not historically it was rule of thumb.

 

[securespark]

It's not good enough is it?

Registered electricians have to buy and keep buying the OSG for the scheme to accept and keep accepting them.

At one assessment, I said I didn't have the latest as I never looked at it, other than to find mistakes, and thought it was a very poor publication (rubbish). I had to order one online there and then otherwise he would not continue.

You obviously upset an OSG lover!

I was assessed by someone once who asked me how far away a cooker switch should be placed, so my reply was there was no regulation covering that.

He went on about the OSG mentioning this that and the other and I asked him to quote a regulation number. He said he would get back to me on that, but never did.

The same guy on another assessment asked me the maximum trip times for a non time-delayed RCD.

"Built to which standard?" I asked.

"It doesn't matter", was his reply.

"300ms" I said.

"Actually, it's 200."

"Yes," I agreed, "for 4293 it is but for 61009 it's 300."

That had him reaching for his books...