New Build - Garage Electrical Changes

[Foosh]

Hi there

Recently moved into a new property and I am looking to turn the garage into a "proper" garage - with a car and everything!

At the moment there is a light and a double socket. Run off the "ground floor sockets" circuit and isolated by a 13A fuse which is in a blanking plate in the kitchen.

In order to have the following:

2 X additional double sockets
2 X additional lights (plus an extra switch)
1 X socket to power a hot tub (plug in garage but hot tub outside)

Would it be best to:

Find the main input and add a small consumer unit with a ring for the lights, one for the sockets and one for the hot tub plug. Changing the 13A fuse in the kitchen for a big red switch with a 13A fuse inside it?

Assuming that is all correct do I need to get it signed off? It is in an attached garage. I would have the assistance of an electrician who isn't fully qualified to sign off work. I am confident in my own ability, changing sockets and light switches and I understand how electrical circuits work. Part P regs confuse me a little, modifying an exisiting circuit in a garage is non notifiable as I can read, but as I'm adding a fuse board?

Advice would be appreciated.

 

[Taylortwocities]

You are limited to 13A,
any hot tub will be much much more than 13amp and will need a separate circuit all to itself.

What is the load of your hot tub?\
What will you be plugging in to those 3xdouble = six sockets? Engine lift? Mig welder? Three bar fire?

You need this information to decide the how what where and (especially) who for this job./

 

[Foosh]

Thanks for the quick reply

The hot tub will be plug and play ie. 13A so will run off a normal plug socket.

Running a battery charger, power polisher - that kind of thing. Nothing really heavy duty like the things you mentioned.

Plus a radio and phone charger and kettle. Also a karcher pressure washer (small one).

 

[Taylortwocities]

Oh, not a "proper" garage at all then

The hot tub will be plug and play ie. 13A so will run off a normal plug socket.

Well, it isn't ever going to achieve its "hot" characteristic!

For what you describe, I would suggest that you need a bigger supply into the garage. Where is the main supply, or the consumer unit, in relation to the garage?

PS Lighting circuits are not "rings" they are radials.
PPS Do not understand what you mean by

Changing the 13A fuse in the kitchen for a big red switch with a 13A fuse inside it?

 

[winston1]

Hi there

Recently moved into a new property and I am looking to turn the garage into a "proper" garage - with a car and everything!

At the moment there is a light and a double socket. Run off the "ground floor sockets" circuit and isolated by a 13A fuse which is in a blanking plate in the kitchen.

In order to have the following:

2 X additional double sockets
2 X additional lights (plus an extra switch)
1 X socket to power a hot tub (plug in garage but hot tub outside)

Would it be best to:

Find the main input and add a small consumer unit with a ring for the lights, one for the sockets and one for the hot tub plug. Changing the 13A fuse in the kitchen for a big red switch with a 13A fuse inside it?

Assuming that is all correct do I need to get it signed off? It is in an attached garage. I would have the assistance of an electrician who isn't fully qualified to sign off work. I am confident in my own ability, changing sockets and light switches and I understand how electrical circuits work. Part P regs confuse me a little, modifying an exisiting circuit in a garage is non notifiable as I can read, but as I'm adding a fuse board?

Advice would be appreciated.

Well if you are only going to be limited to a 13A fuse whether it is as now or in a "big red switch" there is no point in a small consumer unit (which would be notifiable).
Lights are not run in a ring.
Is there RCD protection in the house?
How much power does the hot tub require?

OK lets assume it is less than 3kW and is OK off a socket. Run your garage supply off a new 20A MCB or RCBO (if there is no RCD protection) in your house CU. In the garage all the sockets including the hot tub one can be wired as a radial. The lights can be off the same radial via switched fused connection units with 5 amp fuses.

If 20 amp is not enough you could use a 32A MCB or RCBO and put a ring final in the garage with both ends back to the main CU as the garage is attached. If you are worried about losing lights in the event of a trip you could run them off a new 6amp way on the house CU or even add them to the downstairs lighting circuit.

 

[Foosh]

The house is new and RCD protected.

Not sure on consumption of hot tub - perhaps a "wired in" one would be more suitable given the power required to hear it etc. Therefore I'd have to get someone in.

I'll investigate the costs to get the relevant power into the garage for a more powerful hot tub.

If I decided to simply add a couple of sockets and lights into the current circuit - I'm just limited to 13A at any one time? This is unlikely considering I'll be using LED lights and running all the power tools and kettle at the same time

 

[Taylortwocities]

Yes, your max is 13A.
You'd be suprised at how much you can actually run through a 13A fuse. For a normal domestic garage you'll be fine, unless you wanted to connect up a washing machine and tumble dryer too.

 

[JohnW2]

You'd be suprised at how much you can actually run through a 13A fuse.

Indeed - as we discussed a few months back (click here) , it looks as if a 13A BS1362 fuse would allow about 21A to flow 'indefinitely', and quite a lot more than that for appreciable periods of time.

However, having said that, one obviously should not deliberately plan/design to draw more than 13A from a circuit protected with a 13A fuse, so that one could not advise anyone to use a 13A circuit if there were a reasonable chance that the load would sometimes be appreciably more than 13A.

Kind Regards, John

 

[oceansoul]

You'd be suprised at how much you can actually run through a 13A fuse.

Slightly off topic, we had a power cut at one of our remote sites over the weekend (DNO 11kV cable fault) which has two detached houses nearby. Our site has its own 11kV > 415V transformer, and the two houses have a smaller 11kV - 230V DNO owned transformer. The DNO supplied a small diesel generator for the house and wired this up to the outgoing side of their transformer. Once the owners had settled back down, telly lights on etc i walked past the diesel generator and peeked at its HMI, total load at 230V for two detached houses at aprox 22:00........10A!!! I was quite shocked. Then the DNO turned up with our generator. Huge 900kVA thing!!!!!

 

[Foosh]

I think I'm going to have to call in an electrician, I can't figure out if I can add sockets or lights off the existing work as both the light and the socket are powered from the same 13A fuse box which is part of the ground floor sockets circuit (RCD protected).

I'll have to speak to the Site electrician and check exactly how its been done.

Cheers for your insight thus far, at the least it has persuaded me a properly wired in hot tub is the way to go, with its own supply off the mains.

I'll come back with my findings after speaking to him and then I'll know how easy adding the sockets and lights I want is going to be, and crucially if I need to have it signed off or not.

 

[Foosh]

Just got off the phone to the electrician.

He said that because the sockets and lights are protected by the 13A fuse - which is a spur off the ground floor sockets circuit? - I can add sockets off the one in the garage with no issues. Same goes for the lights. As any load over 13A would "blow the fuse" anyway.

He then said he's check with his "technical man" and let me know tomorrow if that was for definite. I'm now not convinced its been done right in the first place? As a reference, if any of you were wiring a new attached garage, how would you power the sockets and lights? How they have done it, as a spur off the ground floor sockets - which is RCD protected - or another way? Is it worth fitting and MCB (I think thats right) to protect the house from the garage as well as the current 13A fuse - is this notifiable? Or is he right and I can just extend off the current circuit in the garage with no issues?

Once again your advice is appreciated.

 

[winston1]

As a reference, if any of you were wiring a new attached garage, how would you power the sockets and lights? How they have done it, as a spur off the ground floor sockets - which is RCD protected - or another way?

As I told you in post 5 which I'll repeat below.

Run your garage supply off a new 20A MCB or RCBO (if there is no RCD protection) in your house CU. In the garage all the sockets can be wired as a radial. The lights can be off the same radial via switched fused connection units with 5 amp fuses.

If 20 amp is not enough you could use a 32A MCB or RCBO and put a ring final in the garage with both ends back to the main CU as the garage is attached. If you are worried about losing lights in the event of a trip you could run them off a new 6amp way on the house CU or even add them to the downstairs lighting circuit.

 

[stillp]

Hang on, he's an electrician and he has to check with his 'technical man'?

 

[Foosh]

Hang on, he's an electrician and he has to check with his 'technical man'?

My thoughts precisely.

Winston1 I don't really want to change the way it's wired up as this would mean more remedial work than I want to do and my OH would not be happy about that. Also as its a brand new property I shouldn't need to - plus it should comply with all regulations.

As long as I can safely branch off the current sockets and lights then that's fine. I just hope it HAS been done correctly and I'm not breaking the law adding sockets and lights to this circuit

 

[winston1]

Hang on, he's an electrician and he has to check with his 'technical man'?

My thoughts precisely.

Winston1 I don't really want to change the way it's wired up as this would mean more remedial work than I want to do and my OH would not be happy about that. Also as its a brand new property I shouldn't need to - plus it should comply with all regulations.

As long as I can safely branch off the current sockets and lights then that's fine. I just hope it HAS been done correctly and I'm not breaking the law adding sockets and lights to this circuit

It has been done in compliance but you want to add considerably more loading.
Do as you like, though your reasoning is flawed. One 13A feed for 6 sockets, 3 lights, and a hot tub is stupid. Would your OH be happy if the hot tub went cold while she was in it when you operated your electric drill?

What has being a brand new property got to do with whether you need to alter wiring when you are adding substantial loads?