Wiring an Outside Garage query.

[chaban48699]

Could someone please tell me what would be the best way to wire my garage.

I have installed an RCD 30MA mini consumer box in the garage at the moment with two MCB (one for the lighting circuit and one for the garage ring main) and is taking it's feed from a 2.5 twin and earth armour cable coming from a spur on the ring in the kitchen however I am not happy with this setup.

I want to run the feed directly from an empty MCB on the main consumer box in the house but need to know what size cable to use for this?

Also my current setup is it dangerous as it stands at the moment it is currently not live?

Many Thanks

 

[Chri5]

What's the approximate distance between CU and the garage?

What is the likely load (in watts) within the garage. Will it be simply lights and the odd power tool, or is it more of a workshop with heavy machine loads, a electric fire, fridge, freezer, kettle etc..

Taking the feed via a kitchen spur isn't the way forward and as you say a direct cable back to the CU is best.

Post the detail requested and we can tell you the size of cable required, could you also elaborate on the cable route- underground, overhead etc..

 

[chaban48699]

Thanks for the quick reply.

The garage will be used for a washing machine, tumble dryer and a chest freezer so quite a bit of demand on the circuit together with 3 light fittings.

With the current installation all is working well with no problems but as I say am not sure if this is dangerous or not.

The cable is armour and runs in metal conduit under concrete slabs in the patio before going down to the rear of the garden where the garage is. At all times the cable is under either the patio or the concrete base that the garage is on. Changing the cable would not be a major issue if needed as it is run in conduit so would just need to be pulled out.

The approximate distance from the spur in the kitchen to the consumer box in the garage is 65-70 feet (about 22 meters).

If I can leave the current installation safely I will but just need to be reassured that it is safe or if it needs changing.

Thanks again

 

[chaban48699]

Could someone tell me what would be the best size cable to run from the main house CU to the garage CU please and is the current setup safe?
Thanks

 

[jondiy]

What rating are the mcb's down at the garage?

 

[davy_owen_88]

You have connected a cable rated at 29A to a circuit with a protective device rated at 32A so no this is not safe. (You do not mention a fused spur - if you used a 13A fused spur then you are ok although I can't see this lasting long with the load you have mentioned) You are also (most probably) overloading one leg of the kitchen ring circuit.

Have you terminated the SWA properly? Checked disconnection times etc.?

Diversity:

66% of lighting: 0.9A
FL for ring circuit: 32A

Total diversified load: 32.9A

Voltage drop for 2.5m^2 SWA:
18mV * 32.9A * 22m = 13V (too much)

Use 4mm^2 cable on a 32A breaker on the non-rcd side of the house consumer unit. This work is notifiable blah blah, get an electrcian to sort it out.

Davy

 

[chaban48699]

thanks for the replies, as stated I have not gone live with this as I was also concerned about the safety of the cable coming off the kitchen ring. I will run directly off the house CU with the 4mm cable.Many Thanks