Changing consumer unit in garage

GhostWKD · 28 Sep 2017 at 11:16

Hi all,

Got a consumer unit in my garage which has 2 breakers (lights & sockets). Want to get more sockets added but given I've tripped the breakers a few times with existing setup thinking of changing the consumer unit for one with a bit more capacity.

Anyone know how much an electrician would charge for that? I get that its a bit of a length of string question but want to have a bit of an idea before I speak to the electrician

Cheers,
Alex

Kiyoshi · 28 Sep 2017 at 11:47

We paid £400 for a new metal consumer unit to replace our fag stained looking yellow plastic one, it also needed moving slightly in the garage. That included him supplying the unit, and also some spur work and chasing we wanted doing at the time. He was here for the best part of the day and checked all the sockets, lights and switches afterwards.

Jono · 28 Sep 2017 at 12:02

Think I paid £300 all in for someone to do mine.
Main breaker, lights, sockets upstairs and down, separate cooker one... it's a bit weird.
It used to be a fuse box that used stupid sized fuses I could only get from some tiny little shop 25 miles away.

I'm not convinced it's been wired up correctly, since nothing ever broke except the lights fuse once or twice. And maybe the cooker 30A one when I had my old crappy electric thing that died.

But now it's like half my house (left to right) is on one breaker and the other is on another - it's not split upstairs/downstairs?

HardwareGeek · 28 Sep 2017 at 17:07

From the sound of it - garage cu with 2 breakers i am guessing its not your main cu?

In that case you are likely limited by the size of the cable between your main cu and the garage cu...so changing the cu wouldn't help

if i am guessing right you need to find out the size of the cable supplying the garage and what rating the breaker is at the house end - this will be your max power you can draw in the garage... after that maybe you can just keep the existing garage cu and put a higher rated mcb in with some wiring changes

If the existing supply to the garage is minimal then would need a new supply cable running and higher rated mcb at the house end

miller745 · 28 Sep 2017 at 17:58

What are you running to trip the breakers? How many devices are you wanting to run at once and how many amps would that be?

rexehuk · 29 Sep 2017 at 07:09

Jono said:
But now it's like half my house (left to right) is on one breaker and the other is on another - it's not split upstairs/downstairs?

They do it to balance the board rather than by floor. Also its good to have a mix on either side of the board, if your RCD goes and brings down 50% of the board then you're likely to still have lights/sockets on the other side so you don't have an entire floor of.your house completely without electrics.

DXP55 · 29 Sep 2017 at 10:20

A picture of CU would be helpful -- I did work on a modern house once where down and upstairs front was one breaker (sockets) and same at back - good job I checked back upstairs sockets first after changed front ones they were still live - I always thought there was breakers for down and breakers for up.

GhostWKD · 29 Sep 2017 at 11:01

Thanks for replies guys, to try answer a few of the q's;

It's not the main CU, that ones in the house and has a connection to this one in the garage. Times I've tripped it have been running a couple of Halogen heaters in the winter, keen to be able to use heaters & power tools at the same time

Cable going to the garage looks pretty beefy but good shout on checking the garage breaker rating, that may be the quickest check of viability to be fair

Bad photo but one I took when discussing with friends (who it turns out know about the same amount of near zero when it comes to this

)

rexehuk · 29 Sep 2017 at 13:21

It's a 16amp rated I'm guessing for garage sockets. 6amp on left will be for lights.

So the max you can run through it would be like 3.5KW before it could start tripping.

So question is... How much you running at a time?

Also what is the fuse for the garage circuit on the main CU? It seems weird that your garage has a 63amp RCD... Most incoming fuses for houses are 60amp, and can't imagine a huge fuse for the garage supply from main cu?

P.s. not a qualified spark, just rewired my house.

HardwareGeek · 29 Sep 2017 at 17:15

Halogen heaters afaik are usually 2kw (x2) + 3kw for power tools = 7kw which is approx 30A

The SWA looks pretty small but if your lucky it will be 2.5mm and have a 32A breaker at the house end?? if so then you can just change the MCB at the garage end with some wiring alterations to 32A aswell, either rewire sockets in 4mm or convert to ring, ring will probably be easiest

SWA should have the size on the sheath somewhere along its length, hope its on a visible part or you can take the cover off garage cu and check size but that requires some experience to judge just based on the look or measure with caliper and work it out etc

Ps. Turn power off before removing cover and stay clear of the top/incoming terminals of the rcd or turn off at the house end aswell

miller745 · 29 Sep 2017 at 18:28

Or just turn off the heaters while your using the tools, easy + cheaper way

Adam_151 · 29 Sep 2017 at 19:56

HardwareGeek said:
Also what is the fuse for the garage circuit on the main CU? It seems weird that your garage has a 63amp RCD... Most incoming fuses for houses are 60amp, and can't imagine a huge fuse for the garage supply from main cu?

Why? Its not an overcurrent device, the current rating is what it can safely take (and therefor what it should be protected at, at source). While you might think 60A is overkill, its simply one of the most common ratings and therefore resonably cheap, chances are if you buy a 25A one, you are probably paying more, and getting the same with diferent silkscreen printing on!

HardwareGeek · 29 Sep 2017 at 20:14

Adam_151 said:
Why? Its not an overcurrent device, the current rating is what it can safely take (and therefor what it should be protected at, at source). While you might think 60A is overkill, its simply one of the most common ratings and therefore resonably cheap, chances are if you buy a 25A one, you are probably paying more, and getting the same with diferent silkscreen printing on!

That quote has come out wrong..mixed me and rexehuk together

My point was correct that the rating at the house cu will be the current max capacity for the garage supply and together will the cable size will help the op decide the next steps

Agreed rexehuk misunderstood the rating on the RCD, 63a is the most common rating, followed by 80a, 100a and 40a in my experience.

Appears to be just an off the shelf garage cu kit, so whoever fitted just used whatever came with the deal, so 16a might be able to be increased, may have just used 16a as it came with the cu etc

Jono · 2 Oct 2017 at 10:36

C

rexehuk said:
They do it to balance the board rather than by floor. Also its good to have a mix on either side of the board, if your RCD goes and brings down 50% of the board then you're likely to still have lights/sockets on the other side so you don't have an entire floor of.your house completely without electrics.

Cool - kinda thought that might be the reason. My parents' house is upstairs/downstairs.

It went through a period (several hours) of tripping the right side for no reason - unplugged everything (on both sides), still happened. Then it was fine. Engineer came out and tested everything - couldn't find a problem and it went away.

Still not sure what caused it... just had to use extension leads across the house for the freezer/fridge.

Skiddley · 9 Oct 2017 at 14:58

If you're cold in your garage...you're not working hard enough

Hyburnate · 9 Oct 2017 at 15:01

Not 100% sure, not a spark but do work alongside a few working for an electrical company

But, you may need to change out to a metal CU due to new regs.

GhostWKD · 18 Oct 2017 at 15:30

Skiddley said:
If you're cold in your garage...you're not working hard enough

Work smart not hard

Hyburnate said:
Not 100% sure, not a spark but do work alongside a few working for an electrical company

But, you may need to change out to a metal CU due to new regs.

How old are the regs? The house is less than 2 years old so would hope it's not any different now (consumer unit inside the house is plastic too)

HardwareGeek said:
That quote has come out wrong..mixed me and rexehuk together

My point was correct that the rating at the house cu will be the current max capacity for the garage supply and together will the cable size will help the op decide the next steps

Agreed rexehuk misunderstood the rating on the RCD, 63a is the most common rating, followed by 80a, 100a and 40a in my experience.

Appears to be just an off the shelf garage cu kit, so whoever fitted just used whatever came with the deal, so 16a might be able to be increased, may have just used 16a as it came with the cu etc

This is the CU inside the house which then feeds the garage, so it's a 20A jobbie on this end I think?

Hyburnate · 18 Oct 2017 at 17:19

GhostWKD said:
Work smart not hard

How old are the regs? The house is less than 2 years old so would hope it's not any different now (consumer unit inside the house is plastic too)

This is the CU inside the house which then feeds the garage, so it's a 20A jobbie on this end I think?

2016 the regs came in to affect I believe.