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Topic Title: double pole switches sharing a neutral
Topic Summary: Advice/opinions please
Created On: 30 April 2013 11:37 AM
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 30 April 2013 11:37 AM
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aligarjon

Posts: 2738
Joined: 09 September 2005

Hi guys.

i am after a little advice as i am not sure if the job i did this morning is compliant or not.

Last year i took an external supply outdoors for a pond with the provision to maybe do some garden lighting at a later date. I took a 4 core swa out. The circuit is on its own breaker, 17th edition board. It is terminated into an adaptable box and on to the water feature. I used a switched fused spur for isolation in the garage with the spare core made off.

Today i have been back as the customer now wants a filter fitted instead of lights on the spare core. The filter needs a 3 amp fuse also so i fitted a second spur alongside to feed the other core. The problem i have is the neutral. To be able to get both to work independantly i have had to loop the neutrals between switches otherwise if the one switch was off the other would do nothing. The 2 spurs are side by side and i have labelled them both as they are and also that both need isolating if double pole isolation is required. Is this acceptable ?

The CU is directly above the spurs and there is ample room as i fitted it last year, i do have the option of fitting a double pole mainswitch in here to isolate them and change both spurs to single pole if i need to.

I also have the option of using the armour as an earth and using 2 neutrals in my 4 core although this would be a bit of a pain.

Opinions and advice welcome please.

Thanks Gary

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Specialised Subject. The Bleedin Obvious. John Cleese
 30 April 2013 12:39 PM
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AJJewsbury

Posts: 10975
Joined: 13 August 2003

I think your setup - by consequence of the fuses in the FCUs rather than the switches - is effectively two circuits with a shared N, so prohibited by 314.4.

If conditions allow, I'd maybe think of putting the whole lot on one FCU, indicate that that's to be used for isolation, and add separate (SP) functional switching for the filter & pump if required.

On the other hand, if it's 4-core SWA, can't you use two for L+N for one circuit, the other two for L+N for the filter and the armour for c.p.c.?

- Andy.
 30 April 2013 12:49 PM
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aligarjon

Posts: 2738
Joined: 09 September 2005

Duh why didn't i think of that. a single spur with a 2 gang switch would have been easier anyway as it was quite tight . I went with the intension of doing it one way and couldn't see past it . I have to go back to connect the filter when its installed so i'll swap it then. I did tell them i wasn't sure that it was compliant and that i'd check.
Cheers Andy

Gary

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Specialised Subject. The Bleedin Obvious. John Cleese
 30 April 2013 08:06 PM
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Avatar for dickllewellyn.
dickllewellyn

Posts: 1133
Joined: 19 March 2010

Can the fusing be carried out at the pond end effectively making the armoured cable a submain?

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Regards
Richard (Dick)

"Insert words of wisdom and/or witty pun here"
 30 April 2013 09:06 PM
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aligarjon

Posts: 2738
Joined: 09 September 2005

There isn't the room there Dick but thanks anyway.

Gary

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Specialised Subject. The Bleedin Obvious. John Cleese
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