Extending a Consumer Unit

hanrahan · 22 May 2009

Hi I have just bought a house and the consumer unit is full - it is a new unit with an RCD protecting half of the fuses. Is there a way i can extend the unit, I want to add an electric Fire on it's own fuse for safety reasons.

Thanks in advance

ban-all-sheds · 22 May 2009

1) You cannot extend it - the options are to replace it with a larger one or put a 2nd one alongside. The former is to be much preferred.

2) Why do you think this heater requires its own circuit for "safety reasons"? Is it dangerous? What type of heater is it? What's its rating?

3) New circuits and CUs are both notifiable.

Space cat · 22 May 2009

This dodge has been mentioned a few times on here in the past. If you have two 6 amp breakers in there for lighting, replace one with a 16 amp breaker and use it to feed two 5 amp FCUs for your lights. You now have a spare slot for your fire. If the lighting circuits aren't on the RCD side, you can use an RCBO for the fire.

RF Lighting · 22 May 2009

Yeah, and break regulation 314.1 in the process

ban-all-sheds · 22 May 2009

OK - replace the two lighting MCBs with a B40 or B45 and use switched FCUs

JohnD · 22 May 2009

why on eath does an electric fire need its own circuit

there must be something we are not being told.

ColJack · 22 May 2009

ban-all-sheds said:
OK - replace the two lighting MCBs with a B40 or B45 and use switched FCUs

Just to clarify,

in the absence of smileys, I would like to point out that BAS was making the above comment sarcastically..
it is not advice that should be followed...

JohnD said:
why on eath does an electric fire need its own circuit

there must be something we are not being told.

or perhaps he is following the advice set down in appendix 15 of the regs where it suggest that to protect the ring from unbalanced loading, items with a rated power exceeding 2KW is fed by it's own radial..
it specifically mentions cookers, ovens and hobs, but can be extended to most high power fixed appliances ( which is why some people run a separate radial / ring for the kitchen appliances in addition to the general kitchen sockets. )

ban-all-sheds · 22 May 2009

ColJack said:
in the absence of smileys, I would like to point out that BAS was making the above comment sarcastically..

Au contraire.

it is not advice that should be followed...

In what way would it contravene 314.1?

BS3036 · 23 May 2009

I think that it's just that you didn't mention in your DIY advice, that the fcu's need to be within 3m of the CU (433.3.3 etc). Or using thicker wire.

ColJack · 23 May 2009

314.4?

not to mention the very real possibility of some idiot swapping the fuses for 13A seeing as 5A are a non standard size..
we only have 2 standard fuse sizes.. 3A and 13A.. the rest are black to indicate non-standard..

plugwash · 24 May 2009

True though people stuffed 13A fuses in wylex 5A cartridge carriers as well

.

5A are a pretty common size nowadays BTW, anywhere that sells fuses is likely to have them.

mattylad · 24 May 2009

Since when have 5 amp fuses been non standard?

They have been available for years in most places, are used on 5A extension leads & it plenty of equipment.

Sort of makes them standard.

You can get 1,2,3,5,13 amp fuses to fit plugs quite easily.

Lectrician · 24 May 2009

You missed 7 and 10 amp

securespark · 24 May 2009

And with a bit of soldering-iron trickery and modification to the plug top, you could make 4, 6, 8 and 9A fuses too!

Only kidding!

ban-all-sheds · 24 May 2009

BS3036 said:
I think that it's just that you didn't mention in your DIY advice, that the fcu's need to be within 3m of the CU (433.3.3 etc). Or using thicker wire.

This forum would become very cumbersome if every high-level design suggestion needed to be accompanied by a detailed list of every regulation which applied.

ColJack said:
314.4?

Dubious....

not to mention the very real possibility of some idiot swapping the fuses for 13A seeing as 5A are a non standard size..

Idiots can always do idiotic things - it's unrealistic to constrain your designs to ones which cannot possibly be later abused by idiots doing something illegal.

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Extending a Consumer Unit

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