unfused spur from ring in db

[kung]

Hi all

Can someone please explain this for me ?

If you have a ring on 32a mcb etc and you install a new socket and wire it directly into the db on same 32a mcb as ring its a minor works as not a new circuit but i thought it needed an E.I.C. as its a one socket radial and a ring in same protective device as you can remove the ring and the socket will still work as a radial.

Regards

Kung.

 

[Robin Spark]

An Unfused spur supplying one socket outlet of either 1 or 2 gang is allowed to be taken from the consumer unit as you are only adding to an already installed circuit consisting of your protecive device (32a mcb) and ring cct conductor 2.5mm. This is an addition to a cct and so will need a Minor works certificate.

You are not installing a new cct so an EIC would be inappropriate.

PS The cable will not normally be overloaded as its only supplying one socket outlet (max 26amps) however this may depend on your installation methods and keeping the cable away from insulation.

 

[batty]

That does not make sense to me. Surely if you take the lid of the c/u you are adding a new circuit. Personally I would not be wiring a radial of a ring main in this way.

Batty

 

[Bez]

BRB Page 362, Unfused Spur

 

[Robin Spark]

That does not make sense to me. Surely if you take the lid of the c/u you are adding a new circuit. Personally I would not be wiring a radial of a ring main in this way.Batty

Cant see what the problem is if its only 1 socket outlet and its near to the consumer unit. Max current draw is going to be 26amps from a 2g socket outlet so the cable wont be overloaded and the cpc 1.5mm on a 60898 circuit breaker will safely allow any fault current to operate the protective device which can be proven using the adiabatic equation.

Common sense prevails in these sort of situations and you would be stupid if you spurred off the Consumer unit to a quite remote point supplying high load appliances that might be on for a while eg tumble dryer and other kitchen appliances, or if 3036 rewirables were the Protective device in the fusebox

 

[batty]

Cant see what the problem is if its only 1 socket outlet and its near to the consumer unit. Max current draw is going to be 26amps from a 2g socket outlet so the cable wont be overloaded and the cpc 1.5mm on a 60898 circuit breaker will safely allow any fault current to operate the protective device which can be proven using the adiabatic equation.Common sense prevails in these sort of situations and you would be stupid if you spurred off the Consumer unit to a quite remote point supplying high load appliances that might be on for a while eg tumble dryer and other kitchen appliances, or if 3036 rewirables were the Protective device in the fusebox

Well to me it is just poor workmanship so you carry on doing it and I won't.

 

[Bez]

Well to me it is just poor workmanship so you carry on doing it and I won't.

BrB page 362.

" An unfused spur may be connected to the origin of the circuit in the distribution board"

 

[sellers]

Well to me it is just poor workmanship so you carry on doing it and I won't.

I tend to agree with this, but I did ask an elecsa assesor on it on my assessment and he said its fine, and it is a spur off a ring. Not the best of practice but if its to the regs then it is ok.

 

[SPECIAL LOCATION]

Cant see what the problem is if its only 1 socket outlet and its near to the consumer unit. Max current draw is going to be 26amps from a 2g socket outlet so the cable wont be overloaded and the cpc 1.5mm on a 60898 circuit breaker will safely allow any fault current to operate the protective device which can be proven using the adiabatic equation.Common sense prevails in these sort of situations and you would be stupid if you spurred off the Consumer unit to a quite remote point supplying high load appliances that might be on for a while eg tumble dryer and other kitchen appliances, or if 3036 rewirables were the Protective device in the fusebox

Concur.

Fused spur can be connected to ANY point on the ring....

including the bit where cables terminate at the CU!

(obviously good workman would make sure any suitable labels or identification of cables are there to avoid confusion between legs of the ring & the spur cable!)

 

[SPECIAL LOCATION]

BrB page 362. " An unfused spur may be connected to the origin of the circuit in the distribution board"

Concur again! Guinness

Regs say its OK...

and thats OK with me!ROTFWLGuinness

 

[Robin Spark]

Hi Batty,

Of course there are other ways to do this job, we all want to leave a job feeling satisfied that its done the best way.

However as Bez pointed out its in BRB and states on p362

" An unfused should feed one single or one twin socket outlet only. An unfused spur may be connected to the origin of the circuit in the distribution board."

Also using the adiabatic equation and a disconnection time of 0.4seconds then any earth or short cct faults and everything will be fine.

For example i have seen loads of consumer units installed in halls (domestic) with a socket below added as a spur which only ever gets a vacuum cleaner plugged in, so that isnt going to cause any overheating of the cable.

If you want to spur off in 4mm, add another breaker if theres a spareway, or extend ring within CU then thats all good and more future proof. I was just trying to inform OP that it isnt against regs to do what was originally suggested and in reality is no different to adding a spur from any other part of the ring cct.

 

[ian932]

Totaly agree I'd rather see a third leg in the MCB than play hunt the JB for a loose connection in years to come or telling customer they need a new board as there is no spares cus last spark put the skt next to the cu on its own 20A mcb.

How can following the regs p362 be bad workmanship!

 

[Andy™]

That does not make sense to me. Surely if you take the lid of the c/u you are adding a new circuit. Personally I would not be wiring a radial of a ring main in this way.Batty

its still a spur. 7671 does state somewhere that a spur may be taken directly from MCB. electrically, its no different to taking it from a socket.

and how can you add a new circuit if you use an existing MCB for another circuit?! its all one circuit

 

[tom1]

i have done and would do it again, however if there was already a spur in there i would not

 

[Apache]

i have done and would do it again, however if there was already a spur in there i would not

pray tell why? Thought on a ring you could add a spur to each socket?

 

[tom1]

may be 2, but how many can u fit in befor it gets full, thats my only reason for it

 

[batty]

may be 2, but how many can u fit in befor it gets full, thats my only reason for it

On modern Mcb's probably ten.

 

[tom1]

On modern Mcb's probably ten.

would look a bit busy in there,

i bet thats a sight u would not like to see