Can i spur more then once with bigger cable?

[davesparks]

The onsite guide is not for comercial installations.

So im taking a different footing here, the ring circuit design in the onsite guide is for the purpose of a domestic single phase system amongst other prerequisites. So the installed ring is the design of someone? You need to prove it meets the requiremnts of BS7671. Specifically 433.1.103 plus the other general requirements.

Cheers

I thought we were talking about the ring circuit design in bs7671 not the idiots guide?

 

[GEOFF S]

I thought we were talking about the ring circuit design in bs7671 not the idiots guide?

Where is this ring design?

Cheers

 

[davesparks]

Where is this ring design?

Cheers

Read the whole thread, the answer is in post 2, appendix 15.

 

[GEOFF S]

Read the whole thread, the answer is in post 2, appendix 15.

Dave, thats not a ring circuit design, its sets out the special regulation 433.1.103, that asisde its down to the deisgner to meet all the other general requirements.

Cheers

 

[davesparks]

Dave, thats not a ring circuit design, its sets out the special regulation 433.1.103, that asisde its down to the deisgner to meet all the other general requirements.

Cheers

I've not got the book in front of me but I thought that was where there is a full page illustration of the standard ring final circuit with spurs etc clearly illustrated.

 

[GEOFF S]

I've not got the book in front of me but I thought that was where there is a full page illustration of the standard ring final circuit with spurs etc clearly illustrated.

Yes it shows you a typical arrangement, no design spec. The standard circuits in the onsite guide have prerequsites set out, if these are not met then you need to design the circuit and show compliance.

Cheers

 

[Charlie_]

Also that little diagram is based on the ring being wired in 2.5.
In this case as initially explained the ring is wired in 4mm with a proposed 4mm spur

 

[shanky887614]

i wouldn't just guess its 4mm based on vd.

we were laughing at the way overspeced supplies on some jobs.

they were told your not allowed to use anything smaller than 4mm XD

it was for little smoke damper boxes controlling an individual smoke damper.

another personal favorite was a 70mm supply to a panel that only had 50a isolator

 

[davesparks]

Also that little diagram is based on the ring being wired in 2.5.
In this case as initially explained the ring is wired in 4mm with a proposed 4mm spur

Without further information we have to assume a worst case scenario that 4mm has been used due to de-rating factors making the ccc of 2.5mm too low for a ring. So without further information we cannot assume that the 4mm when de-rated has only got the ccc of the 2.5 in the standard circuit.