Radial circuit and the use of spurs

[davesparks]

FYI: This DIYer has a first class Electrical Engineering degree. However that was many years ago and I am far from up to speed with currect Regs. I had hoped that this forum would provide reliable advice, rather than facetious comments.

Forget the degree, just use a little common sense!
Every joint is a potential point of failure, common sense says you don't add a load of unnecessary joints.
If you are insistent on adding unnecessary joints then why not use 4mm for the branches?

 

[Octopus]

As mentioned earlier, I was under the impression that there was a 33 metre limit on total cable length with this type of circuit. This I have seen referenced in various places e.g. Domestic Circuits - SimplifyDIY - DIY and Home Improvement Solutions.

Hum..........

 

[davesparks]

As mentioned earlier, I was under the impression that there was a 33 metre limit on total cable length with this type of circuit. This I have seen referenced in various places e.g. Domestic Circuits - SimplifyDIY - DIY and Home Improvement Solutions.

What a load of utter nonsense, how can people get away with publishing such Ill informed and incorrect rubbish?

Ignore the ramblings of strangers on the internet and follow the wiring regulations!

 

[Tradewind25]

If you are insistent on adding unnecessary joints then why not use 4mm for the branches?

1. I have already agreed that 4mm throughout would be better.
2. The "unnecessary" joints are due to my understanding that there is a max cable length.

 

[Octopus]

You can lead a horse to water......."

 

[Robson689]

What a load of utter nonsense, how can people get away with publishing such Ill informed and incorrect rubbish?

Ignore the ramblings of strangers on the internet and follow the wiring regulations!

I think it's on about the volt drop for clipped direct t&e it doesnt go into enough detail though

 

[Richard Burns]

After 33m the volt drop on a 4mm² cable will exceed the 5% limit indicated by the wiring regulations.
A run of cable in smaller size than the supply cable would be considered a spur, rather than a branch.
It is recommended that the number of spurs is fewer than the number of sockets directly on the circuit.

Whilst this is a potentially possible solution it is by no means ideal, also you can have exactly the same arrangement in 4mm² cable as you have in 2.5mm² cable you will have the same cable length, which is presumably less than 33m.

If you were to run the spurs as you have suggested then you are even more likely to have problems with voltage drop as the reduced conductor size will increase the volt drop and so reduce the allowable circuit length.

 

[Darkwood]

FYI: This DIYer has a first class Electrical Engineering degree. However that was many years ago and I am far from up to speed with currect Regs. I had hoped that this forum would provide reliable advice, rather than facetious comments.

It is clear your not up to date with regulations and tbh Electrical Engineering does not in itself give you the knowledge for domestic work so with all respect I would ignore the invited comments and let's move on with the thread ...

We all know the OP's background now ... had he answered my post 2 we could have avoided all this, so can we either offer good advice or refrain from comment