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Discuss 3p breaker feeding 3 x 1p circuits in the DIY Electrical Forum area at ElectriciansForums.net

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Hi everyone.

I may be blind but I can't find a definitive answer.

Can I use a 3 pole breaker (originally feeding a massive 3 phase heater) to feed 3 single phase circuits?

I've run seperate neutrals for the 3 new circuits and the breaker is rated for the load required - 30a per phase (I'd be installing 3 x 32a breakers if I could, but the age of the board makes this a pain).

Killing all the circuits in the event of a problem won't be an issue - they're all in my workshop.

So - is it permitted?

There are no socket outlets involved
 
It will still function as would a single-pole device but you will lose three circuits if a fault occurs on one. Not the end of the world but probably falls foul of Reg 314.2, what make is the board.
 
  • Thread Starter Thread Starter
  • #3
Not worried about losing 3 circuits in the event of a fault. Board is a square D circa 1990 full of old black QO breakers.

The whole installation is going to be inspected so it needs to be right - or at least acceptable.
 
Problem with the device you have reused is that it is a Type 4. How have you proved disconnection times will be met.
 

Charlie_

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Arms
A fault on one circuit shouldn’t effect another circuit?
Also because they are all on the same ocpd would it be classed as one circuit not 3?
 
  • Thread Starter Thread Starter
  • #7
Oh cool - saw those they're not exactly the same but the look like they'd fit.

I've attached an image - I'm replacing the top 3p breaker.
IMG_20190706_182822.jpg
 

telectrix

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Mentor
Arms
Esteemed
£14. that's cheap.had to get a 32A 3p QO MCB for a garage rolling road. £116 + VAT.
 

telectrix

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Mentor
Arms
Esteemed
if i remember, the rolling road was fed from a 20A 3 phase MCB with a 6.0mm SWA. clowns came and installed a new machine 27A/phase and wondered why it was tripping out on load.
 

Charlie_

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Arms
if i remember, the rolling road was fed from a 20A 3 phase MCB with a 6.0mm SWA. clowns came and installed a new machine 27A/phase and wondered why it was tripping out on load.
And the same clowns were still sat there in the van trying to drive home
 
Westward they are a big item 3phase breakers I’ve seen them from 15 amps to 4000 amps and they sell them a lot of them hers
We are talking miniature circuit breakers here the Square D QO range which are discontinued. Schneider who bought them out still produce single pole devices but not triple pole.
 

Megawatt

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Arms
We are talking miniature circuit breakers here the Square D QO range which are discontinued. Schneider who bought them out still produce single pole devices but not triple pole.
Sorry I didn’t know westward
 

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