power to me shed

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I have a 'garage unit' in my shed with 1 RCD and space for only 2 MCBs.

I have run a radial 1.5mm circuit for the lights from the 6A MCB and a 2.5mm ring circuit for the sockets from the 16a MCB.

Trouble is, I want to plug in a 3KW Dimplex heater (tough doing precision routing whilst shivering). Do I have to run a separate radial circuit for this (i.e scrap the 'garage unit' cos it doesn't have room for another MCB) or can I just replace the 16A MCB with a 32A and be done?

All replies gratefully received - this chilly girl wants warming up!!
 
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check your loadings and cable feed to your shed. Where is that comming from and how is it fused. As you are aware 3kw on a heater is a load in itself to consider. Hope you planned for that before starting.
 
Feed to the shed consumer unit was done by local sparky from a 40a MCB in the house consumer unit (using armoured cable, as it's buried in the garden).

"Hope you planned for that before starting"

...If I'd thought about it beforehand, I would have started by dating an electician, but it wasn't this cold in August! :)

So, can I change the 16A for a 32A and plug in my 3KW heater or should I buy some thermal vests?

Cheers!
 
As long as you are sure you have a 2.5mm² ring, as opposed to a 2.5mm² radial, then yes, you can swap the breaker for a 32A one

EDIT: Make sure you switch off the incommer before swapping breakers, as its a submain, you can even be doubly safe by switching off the submain breaker in the house as well
 
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Yup, I started at the Garage Unit, connected all my sockets like a daisy chain and finished up back at the unit.

Goody - thanks everyone, really helpful :D

EDIT: I'm such a safety-freak - I'd have the National Grid turned off first if I could!
 
Oh and I better tell you, this work comes under the scope of notification under part P of the building regs

Should you notify your local building control? Yes

Would I notify the building control if it was me? Doubtful ;)
 
tyger said:
EDIT: I'm such a safety-freak - I'd have the National Grid turned off first if I could!
please dont! We would all be deprived of DIYnot.com then! :confused:
 
Just a query, why must it be a ring circuit to swap from a 16amp to a 32amp mcb.

If you had a radial 2.5mm², can you not do the same?

Just curious.
 
I found that a bit confusing too - if 2.5mm isn't rated for 32a, how come you can use it on a 32a protected ring main, but not on a radial? Is it because if you have a ring, there's power arriving from each direction? Sort of makes sense, but could anyone explain it a bit better?

Cheers
 
tyger said:
I found that a bit confusing too - if 2.5mm isn't rated for 32a, how come you can use it on a 32a protected ring main, but not on a radial? Is it because if you have a ring, there's power arriving from each direction? Sort of makes sense, but could anyone explain it a bit better?

Cheers
Yup,
The sockets on a ring main have two lots of 2.5mm² cable going to them allowing two paths for the current to flow.

In a radial, you only have one cable hence there is only one path for the current to flow. The one cable must be capable of carrying the full load current of the circuit.
 

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