Garage Consumer Unit

[carosio 185]

I need to upgrade the old fusebox. The garage is a concrete sectional with a small workbench. The house supply is separate L/N with earth strapped to the lead sheath.

So what type would be a suitable unit, bearing in mind the garage can get damp at certain times, especially when there's been a fast rise in temperature in cold weather.

[rudds1 102]

You can buy dedicated garage consumer units. ,I’ve never had a problem with my unit although mine is a normal house one I used 

[carosio 185]

1 hour ago, rudds1 said:

You can buy dedicated garage consumer units. ,I’ve never had a problem with my unit although mine is a normal house one I used 

I understand that with my supply arrangement, the earthing in a building remote from the house should(?) be grounded close to that building, ie, a ground rod adjacent to the garage.

[Bargepole23 337]

3 hours ago, carosio said:

I understand that with my supply arrangement, the earthing in a building remote from the house should(?) be grounded close to that building, ie, a ground rod adjacent to the garage.

Your supply arrangement is TN-S from your description. No reason why you cant export the earth to the garage. Would the supply out to the garage be RCD protected?

[carosio 185]

No, not in the house, older type MCB board

[Bargepole23 337]

9 hours ago, carosio said:

No, not in the house, older type MCB board

How long is the cable run from house to garage?

 

And what is the current earthing arrangement?

Edited December 19, 2019 by Bargepole23

[carosio 185]

I'll get back to you a bit later with the cable length, presently the earth is connected to the house system.

[carosio 185]

Cable length is approx. 21 metres end to end. It's standard 2.5mm cable running through a protective tube between the buildings.

[Bargepole23 337]

So to do it properly you need to do some calcs to determine earth fault loop impedance of your circuits. You need the efli to be low enough so that if there is a fault, your circuit breaker will open quickly enough to meet the minimum disconnection time required by the regs. The efli value is dependent on the earth conductor sizes, so the earth in your 2.5mm cable is part of that circuit.

 

An electrician will calculate and then measure the efli to determine that your new install is safe. I'm assuming you don't have the knowledge or kit to do this.

 

RCD protection makes achieving disconnection times much easier.

 

In short, get an electrician if you want a compliant and safe installation.