Ok to add socket for microwave?

Away now until next week, from memory they're all General Electric, box included
Sponsored Links
In that case, the circuit is already at its limit. A new circuit would be best.

Add at least one new Radial Circuit for the Kitchen and leave the Fridge on the "Side-Lounge" circuit.

North Americans are often accused of having too many separate circuits - for their (mainly) 120 V (high-current) AC.
(Built-in Microwave Ovens in North America are REQUIRED to be on an individual [15 A - or 20 A] circuit.)

However, those in the UK seem to have too few separate/independent circuits.
Any modern UK Kitchen should have at least two separate 20 A circuits and it would be preferable if the Fridge were not on one of those but on a different low load Lounge/Bedroom/Other 20 A circuit.

All circuits should be supplied via RCBOs.
Maybe the Fridge and / or boiler could be put on to the immersion circuit - it draws approx 12.4A (a 2.85kw element) through 2.5mmsq protected by a 20A, so there would appear to be room for it - but does this go against regs? They are all fixed permanent devices with switched isolator units, if there's space then why not.

FrodoOne I don't know how they would add another B20 circuit due to board space.. although, there are a lot of B10 lighting circuits using very few lights, maybe could amalgamate two of those circuits on to one 10A, and swap out the 10A for a 20A which could then take the fridge and/ or boiler. Doesn't the fridge use very little power anyway, about 0.4A?
Last edited:
Sponsored Links
I know it‘s frowned upon but both the fridge and the boiler could very well run on a lighting circuit. Both are very small loads.
As promised. There's no room for another B20 on the top rail unless the busbar was extended.


  • 20240304_150014.jpg
    268 KB · Views: 73
North Americans are often accused of having too many separate circuits. However, those in the UK seem to have too few separate/independent circuits.
One 32A socket circuit (plus a seperate cooker circuit if the cooker is electric) has worked just fine for UK kitchens for donkeys years.
I suppose everything is bigger in America!

So it looks like some of the appliances could be moved on to a new 20A there, hopefully stress free. FrodoOne, are you sure it would need to be a RCBO? Wouldn't a usual Type B single pole suffice.
Hello Everyone,

I just want to make sure I'm ok adding this new socket for a microwave.

I plan on putting in a single socket on a 13A fused switch and linking it as a spur from the existing radial circuit. It will be in 2.5mm2 T+E, running from a circuit which is protected by a 20A circuit breaker. The cable will be run in surface trunking over tiles vertically and across in to a cabinet, all sealed safely. On the board, it shares a 63A RCD with four other 20A fuses.

I have attached a diagram showing what is already on it.

View attachment 334860
Thanks for the good sketch and pic.
To my mind the most obvious thing to do is run a 2.5mm² cable from your new Microwave FCU back to the consumer unit and convert it into a ring.
Install a new 32A RCBO in the vast spare space which is not on either of the existing RCD's. It wouldn't matter too much what make as there is already a selection of devices in there.
That will also reduce anxiety about the size of the RCD.
However I'm not there and cannot see the routes or difficulties involved.

EDIT: making changes to and within a consumer unit is not a DIY job.
Last edited:
Thanks Sunray, no we've decided it's too much mess for the minute. Yep for sure nice to understand what's happening with the board and although I have some confidence after many years, I value the house insurance too much!

Future proofing in mind two radials would be best I think, but splitting it is another matter. I'd say keeping the fixed appliances on one circuit is best as you wouldn't want a kettle tripping the boiler! Probably fridge, boiler, dishwasher, internet router, extractor hood, and maybe microwave on one 20A, and then worktop sockets would be on their own 20A. I guess we could pull out the units from under the worktop to access that cabling when the time comes.
Last edited:
Are you actually in the UK? That‘s definitely not a typical UK consumer unit.

I‘d strongly recommend replacing all the non-matching MCBs, the bus bars don‘t fit and that could definitely cause overheating.
West Midlands! Anything's possible up here :) We are in about 7 years, never had anything done with it. Probably needs a full going over but hopefully not a replacement!

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links