Upgrading power to garage

Pembrokey · Mar 19, 2017

Hi there please excuse my newbieness. I'd just like a bit of advice with regards to upgrading the power in my garage if possible before I contact a local electrician, or if it is something I'm allowed to still alter myself.

I had power installed in my garage a couple of years ago, when to be honest I just wanted the odd socket and some lighting. I've now turned it into a workshop and need a bit more power and wondered if you could tell me if it's as simple as just getting the breakers swapped out to something beefier or something more complex.

The garage is fed from a 32 amp breaker on the houses main consumer unit via the following cable 'Prysmian LV Armoured 6943X 3-Core Cable 6mm² x 25m Black'

The consumer unit in the garage was the smallest one I think screwfix did at the time, can't find a similar model still available but the specs are an RCD of 40amp with a B16 and B6 breakers. (photo attached)

Ideally the light circuit is fine but would like to increase the B16 breaker to a B32. Would I be able to just get the B16 swapped out to a B32 or would I also have to upgrade the 40amp RCD and or the 32amp breaker on the house unit?

Any advice would be gratefully received, many thanks

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Deleted member 26818 · Mar 19, 2017

The B16 MCB is protecting a socket circuit.
This socket circuit is most likely a radial circuit.
It may be possible to upgrade to a B20 MCB without altering the circuit.
Anything higher would require either replacing the existing circuit wiring, or changing the circuit from a radial to a ring.

Rpa07 · Mar 19, 2017

Sound advice above - what do you intend to be using in the workshop? Will there just be you? One tool at a time? Will you wear a sweater instead of plugging in a heater?
You may not need to upgrade but you do have scope if it is required - well done for forward thinking, so few do these days!

Wilko · Mar 19, 2017

Hello and welcome to the forum.
Are you having any problems with the installation / why do you think it needs expansion?

Pembrokey · Mar 19, 2017

Thank you both, yes you're right it is a radial circuit from that consumer unit. It would be nice to get higher than 20amp out of it as you've gueesed it Rpa07 I'm wanting to keep my feet warm whilst I'm working and am tripping out if I put on a beefier heater! It is only me working in there so it is only really one machine at a time. But I have a laser engraving machine which requires power for itself plus a chiller extractor and compressor. I'm estimating that with that running, lighting and a 2.5kw heater (which is enough in autumn and spring but not quite enough for winter) that I'm drawing around 14 amps if everything is at full chat.

I'm guessing it would still be a relatively inexpensive job for a spark to upgrade it to a ring, ie a few hours plus parts type money? I believe the cable to the garage is capable of a bigger supply? I won't take the credit for that though, I remember discussing with the electrician at the time it would be sensible, just in case, as it's buried beneath a concrete pad.

Rpa07 · Mar 20, 2017

I agree, whilst you still have a chance to upgrade the radial to a ring, do it. Concider a bigger MCB of 20, your lighting circuit is probably pulling a pittance so regarding overloading, taking into account your heater will be thermostatically controlled - suck it and see after the work is done.
Keep asking the questions.
You're also correct about the feed, even at 25 metres it a good cable capable of more so it will not be your weak link.