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Topic Title: 110V and 230V in a RCD consumer unit
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Created On: 28 September 2017 08:29 AM
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 28 September 2017 08:29 AM
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chrisbell911

Posts: 2
Joined: 27 September 2017

Hello, I am wondering if you can have multiple voltages in a RCD consumer unit, but have found it hard to clarify.
Can you have 1 consumer unit (but split) so 1 RCCB and 2pole MCB's for 110V and another RCCB with single MCB's for 230V.
Difficult to find an answer on google?
Thanks Chris.
 28 September 2017 10:34 AM
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broadgage

Posts: 2387
Joined: 07 August 2007

If the 110 volt supply is derived from a transformer that takes its supply from the 230 volt side of the consumer unit, then I would consider it acceptable since turning off of the main switch would isolate everything.

If however the 110 volt is from other source, then this is very poor practice IMO due to the risks of confusion, even if not specifically prohibited.
 28 September 2017 10:45 AM
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mapj1

Posts: 9371
Joined: 22 July 2004

And if for an reason the mixed voltages are wider spaced require it may be worth considering segregation or thicker insulation.

Certainly, it can be done, actually dual source supply can be done too, but needs careful layout and very clear labelling. There are not that many many cases where it is the best approach.

-------------------------
regards Mike
 28 September 2017 01:59 PM
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sparkingchip

Posts: 9962
Joined: 18 January 2003

Would you put a din rail transformer in a consumer unit to supply a door bell or the like?

Andy B.
 28 September 2017 02:05 PM
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ArduinoXR

Posts: 34
Joined: 16 August 2017

Originally posted by: sparkingchip

Would you put a din rail transformer in a consumer unit to supply a door bell or the like?



Andy B.


There's no problem with that at all.

.It takes its supply from the 230v side of the same CU and It is SELV.
 28 September 2017 07:01 PM
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AJJewsbury

Posts: 15838
Joined: 13 August 2003

Would you put a din rail transformer in a consumer unit to supply a door bell or the like?

Yes, I've done that - you just have to be careful about the insulation and/or routing of the ELV side.
- Andy.
 28 September 2017 08:58 PM
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ToniSM

Posts: 329
Joined: 21 November 2006

I have installed a dual voltage split board. The 110V was from a 250/110V autotransformer supplied from the 250V side. With an autotransformer both sides share a common neutral and therefore the 250V RCD also covers the 110V side.

As to if this is a legitimate way of doing it I wasn't really interested as it was for my own photographic darkroom.

-------------------------
Could there be a better way?

In theory yes, but in practice?
 28 September 2017 09:08 PM
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mapj1

Posts: 9371
Joined: 22 July 2004

Would you put a din rail transformer in a consumer unit to supply a door bell or the like? Andy B.


yep, with mains rated oversleeving of the bell wire until it gets outside ...

I have also been responsible for a system where 400V, and a few other odd voltages (48DC and others) were created from 230 in a din rail box, with normal CU style breakers and so forth also, so a sort of bespoke CU. Nothing a bit of logical layout could not fix.

-------------------------
regards Mike
 29 September 2017 04:34 PM
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anastasis

Posts: 669
Joined: 01 September 2009

I recently saw a London bus stop with a cover open. The bus stop has an LED display giving details of the next buses, plus the usual illuminated adverts, all needing power.

So under the cover there was a large plastic IP65 DIN rail enclosure - it contained an RCD and 5 MCBs (Chint), clearly running off the incoming DNO supply - there were incoming 6181Y tails disappearing downwards into another compartment. But the enclosure also contained two DIN rail contactors (Finder), with 12V and 230V coils, and two things that the label said were transformers but were actually DIN rail mounting 12V and 24V switch mode power supplies (Meanwell). The PSUs appeared to be feeding an industrial 4G router (to receive bus arrival times) and another gadget, both in an adjacent plastic enclosure with clear lid.

Interesting setup, constructed to a decent standard - I took some photos if anyone would like to see them.

But obviously to JC Decaux (who have the bus stop contract) the presence of 240VAC, 24VDC, and 12VAC in the same enclosure was not an issue.
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