Advice on power from garage to home office cabin - if it is possible?.

[spikeuk36]

Hi,

Currently in process of building home office in our garden, not far from garage which already has power (approx 10 meters). Garage in turn is approx 25 meters or so from our house consumer unit.

We are looking for quotes to run a underground cable from garage to office - and if its actually possible to run power from our garage.

I am now asking electricians to quote however I would like some advice first on if this is even possible to connect to our garage or would a new run to the house be required?

I suspect the fuse board in the garage would need to be upgraded?

We would like to get power to the home office, for approx 2 wall sockets and a couple of lights.

Garage has 2 x double sockets, and 2-3 strip lights, an outside sensor light with isolator switch.

Any comments or advice on what can be done would be greatly appreciated so I know whats possible /to be expected when we get a quote.


House consumer unit with garage connection highlighted in red :

Garage fuse board: I suspect this needs to be updated to allow another connection to the home office? and to bring it up to modern standards?

The illuminated isolation switch at bottom of photo is for our sensor light, I think the 15A blue fuse is for the power sockets in garage.

 

[chivers67]

You need to find out how the Garage is cabled and then we can determine how best to approach this (but personally i'd have a separate feed). Ideally the Garage & Home office should have their own RCD/RCBO discrimination if a fault occurs otherwise the house circuits on the RCD will lose power too.

 

[SUNRAY]

Ideally the Garage & Home office should have their own RCD/RCBO discrimination if a fault occurs otherwise the house circuits on the RCD will lose power too.

Always my preferred option and whenever possible/practical have the RCD in the outbuilding to save the walking when it does trip.

 

[JohnW2]

Always my preferred option and whenever possible/practical have the RCD in the outbuilding to save the walking when it does trip.

Indeed. However, it's not uncommon for the path from the house (CU, Switchfuse or whatever) to have at least some buried non-armoured cable (e.g. T+E), in which case that cable would, at least strictly speaking, require upstream RCD protection.

Kind Regards, John

 

[SUNRAY]

whenever possible/practical.

 

[JohnW2]

whenever possible/practical

Indeed - I was merely pointing out a reason why it quite often might not be possible/practical (at least, in terms of regs).

Kind Regards, John

 

[SUNRAY]

Indeed - I was merely pointing out a reason why it quite often might not be possible/practical (at least, in terms of regs).

Kind Regards, John

I'm sure there are other reasons too, I tried to make it simple.

 

[Taylortwocities]

@spikeuk36
Let’s rewind to the beginning. what will be the load required in the office building? Make a list. Don’t forget you’ll need heating in the winter. Any hot water requirements?

 

[spikeuk36]

-Power for Laptop + monitor
- Power for desk lamp
-Power for LED downlighters.
-Enough power for a plug in electric radiator.

no kettle etc, no hot water.

 

[Taylortwocities]

In my opinion, you have a 32A connection to the garage.
I see no point in updating the existing fuse box in the garage to provide a new circuit. The existing one us doing it’s basic job.
If you put an MCB in there it would have to discriminate with the 32A MCB in the house and that would greatly reduce the total current available at the office to maybe only 16amp.

I would simply extend the feed to the garage on to the office thus providing a total of 32A. A small CU in the office to provide isolation for the various circuits there. It will not need an RCD, there’s already one at the house end.

You’ll need an electrician to design the cable sizing as will have 10+25 metres distance from the supply. We have no information on the cable sizes on the existing feed to the garage.
the electrician will be the one who needs to certify and NOTIFY this work. better to find one and ask him your questions.

PS Send a pic of how the power feed comes in to the garage and connects to the garage fuse board. Will better be able to judge what might be achieved.

 

[Tigercubrider]

Assuming the cable is underground, you'd save money by digging the trench (possibly burying a conduit/duct) and filling it in, as the electrician's rates would be higher than diy/ a bloke who digs holes.

When a gas pipe in the kitchen needed work, the gasman took a look, told me where to cut the concrete back (chisel) and came back a week later to do the difficult bit

Obviously talk to the sparky about what he needs you to do and how to protect the cable/duct. I only suggest duct as a future benefit outweighs any negligible costs. Don't forget a rope inside any duct