Volkszone Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
1,064 Posts
Discussion Starter · #1 ·
As some may have been following on the house buying thread, I have been in my new house since April, and have now started on the garden office that I have been planning on and off since before we moved. I'll probably start a separate thread on that if anyone is interested, but I have some specific questions regarding the electrics.

The office is in the top corner of the garden (with stunning views of the Welsh mountains and valleys) about 60 metres from the house. We had our electricity meter re-located to an external box, so the main switch is there, and will be where I take a feed from. Between the house and the office is the existing outbuilding, a large "Nissen Hut" structure that I am using as a store and workshop. This will most likely be replaced at some point next year, when I have the funds to get it removed (asbestos panel roof) and a new slab laid.

My idea is to run a heavy armoured cable along the boundary behind the workshop and then put in a suitable enclosure containing some heavy-duty connector blocks. I can then run the rest of the way to the office with some lighter cable, and can either take a feed for the existing workshop and/or use it to supply the new workshop when that gets built. I need to work out loads first to calculate the cable sizes, but is that a reasonable plan?

If it is sound, then any recommendations for equipment to use would be great, especially for the connections in the outdoor enclosure.

Second question is how much of this I can do myself. I am fairly competent with electrics, know my way around the regulations to a reasonable extent, and would much rather do as much of the work myself as I can. Is it reasonable to find a friendly electrician who could perhaps come and inspect after first fix, then come back and test the install later and do the actual connection to the mains? I would imagine that getting a bit of cash for a few hours work would be attractive, but not sure whether anyone would sign off what they haven't installed. Thoughts?
 

·
Premium Member
Joined
·
15,620 Posts
I don't know about loads etc, but can I make an alternative suggestion.

You're going to have to dig a trench to the workshop and to the office, whatever you do. Why not run a length of armoured cable to each?

You'll be able to run what you like in each building. There won't be any joins in the runs. The only downside is the cost of the cable.
 

·
Registered
Joined
·
1,601 Posts
Your idea will work, however you’ll have to size your protective device to the smaller cable, ie. if you ran a 10mm2 out from the box, then joined it to a 2.5, you could only fit a 20a mcb rather than a 40.
When you build your unit in the middle, you could fit a consumer unit in there, and then feed the office from that with the smaller cable, on a lower amp MCB, and then upgrade the one in the box to have a bit more capacity.
As for cable selection, Doncaster cables do a good online calculator that will help with choice.
 

·
Registered
Joined
·
1,064 Posts
Discussion Starter · #4 ·
I don't know about loads etc, but can I make an alternative suggestion.

You're going to have to dig a trench to the workshop and to the office, whatever you do. Why not run a length of armoured cable to each?

You'll be able to run what you like in each building. There won't be any joins in the runs. The only downside is the cost of the cable.
If I didn't have a fairly tight budget, this would be what I'd probably do. Problem is that cables seem to come either by the meter, or in 50 or 100m drums, so I wouldn't be able take advantage of the 50m drum pricing. I also have some cable that may or may not be the right length and/or size to do the bit to the office.

Your idea will work, however you’ll have to size your protective device to the smaller cable, ie. if you ran a 10mm2 out from the box, then joined it to a 2.5, you could only fit a 20a mcb rather than a 40.
When you build your unit in the middle, you could fit a consumer unit in there, and then feed the office from that with the smaller cable, on a lower amp MCB, and then upgrade the one in the box to have a bit more capacity.
As for cable selection, Doncaster cables do a good online calculator that will help with choice.
That's a really good point that I had not thought of, thanks. The box outside the house contains only the meter, the main fuse and main switch, then there are tails to the consumer unit in the house. Would I need to add another breaker in there for the feed to the outbuildings, or can I simply take a direct feed from there to a new 2 way consumer unit in the middle, with suitable MCBs for each building?
 

·
Registered
Joined
·
1,601 Posts
Depends on how the meter box has been laid out if you’re coming out of there, you would need to install tail blocks between the meter and your current DB, new tails to a small DB fitted with either an RCD main switch and MCBs or main switch and 2 RCBOs
I’ve done it before, but it will be a bit of a squeeze to get it in the meter box, and armoured cable and 25mm2 tails can be a bit awkward to form tight bends!
 

·
Registered
Joined
·
6,453 Posts
I did this 3 years ago as one of the first big jobs I did here. Well worth doing properly. Did most of it myself. Not rocket science.

Don't worry about the chaos, mud mess and dead plants - you won't notice anything after 9 months.

Check online for the data but there is a minimum depth for the trench. If you are going to trench you may as well put blue water pipe down there as well. I did and I'm glad.

One line from the house to my workshop - breaker box in there and then back down underground and onwards to a big shed with its own "fuze box".

Put the pipe in first then the cable all in pea shingle. There is marker tape to buy too - yellow with written warnings on it. In case at a later date someone starts to dig on top of this lot.....there is a minimum depth to put this in and a gap to have between the tape and the cable. Back fill with earth. Did this all in 2 days with a mini digger.

Don't under estimate the power needs of the buildings and future possible "upgrades". So soak up the pain of the cable price now. In a couple of years when you pop that fan heater on in the workshop or spark up that TIG welder, you'll be glad you did it "proper"
 

·
Saddest VZi'er 2020
Joined
·
6,742 Posts
I ran some 10mm sq cable out to my garage a number of years ago. I was lucky, and bought a “drum end” offcut from an ebay seller almost exactly the right length, and for a fraction of the cost of buying it either by the metre or a whole roll.
 

·
Wannabe Chat Slut
Joined
·
1,548 Posts
Check out this site for buying cable by the metre. I have bought loads of stuff from them over the years, they are very reliable to deal with.

 

·
Registered
Joined
·
1,064 Posts
Discussion Starter · #9 ·
Depends on how the meter box has been laid out if you’re coming out of there, you would need to install tail blocks between the meter and your current DB, new tails to a small DB fitted with either an RCD main switch and MCBs or main switch and 2 RCBOs
I’ve done it before, but it will be a bit of a squeeze to get it in the meter box, and armoured cable and 25mm2 tails can be a bit awkward to form tight bends!
I'll get some pictures at some point, but we told Western Power (who did the cabling) what we planned, and I think they have left space for it. In fact, the guy from SSE who installed the smart meter had quite a job getting the meter in right at the top as there was not enough room to drop it on to the tails. In the end he had to make up really short tails and it just about went in,

I did this 3 years ago as one of the first big jobs I did here. Well worth doing properly. Did most of it myself. Not rocket science.

Don't worry about the chaos, mud mess and dead plants - you won't notice anything after 9 months.

Check online for the data but there is a minimum depth for the trench. If you are going to trench you may as well put blue water pipe down there as well. I did and I'm glad.

One line from the house to my workshop - breaker box in there and then back down underground and onwards to a big shed with its own "fuze box".

Put the pipe in first then the cable all in pea shingle. There is marker tape to buy too - yellow with written warnings on it. In case at a later date someone starts to dig on top of this lot.....there is a minimum depth to put this in and a gap to have between the tape and the cable. Back fill with earth. Did this all in 2 days with a mini digger.

Don't under estimate the power needs of the buildings and future possible "upgrades". So soak up the pain of the cable price now. In a couple of years when you pop that fan heater on in the workshop or spark up that TIG welder, you'll be glad you did it "proper"
Thanks, all good points. Was planning on running in Ethernet and a water pipe. For the workshop I'd like to overspec to future proof it, which is part of the reasoning for a split run.

I ran some 10mm sq cable out to my garage a number of years ago. I was lucky, and bought a “drum end” offcut from an ebay seller almost exactly the right length, and for a fraction of the cost of buying it either by the metre or a whole roll.
Check out this site for buying cable by the metre. I have bought loads of stuff from them over the years, they are very reliable to deal with.

Will check these options out - I need to see what type of cable I already have and how long it is,
 

·
Registered
Joined
·
1,601 Posts
Just had the slab laid in the garden of my new place for my garage, 6m x 10m,
Shade under 6k, been quoted 3.5k for the blockwork, single skin.
I’m running a 25mm cable out to it, due to the distance, with network, future proofing it in case I need to fit an EV charger.
Cable is costing me £500, that’s the trade price!
But it’s going to be epic!

 

·
Registered
Joined
·
6,453 Posts
I wish I had sunk some pipe for the interweb at the same time as the water and power went in.
 

·
Registered
Joined
·
1,064 Posts
Discussion Starter · #12 ·
Bringing this up to date, I decided in the end to run a cable just for the garden office as it was jsut too much trouble to try splitting it, and when we do get around to rebuilding the workshop, we will be having a new slab laid anyway, so it's no big deal to get a cable put in then. Looked at hiring a trench digging machine, but in the end it was cheaper to get our local builder along with a mini digger, and it was all done in a day. We did have one false start when we discovered that the outside tap was not fed from the house, but from the old water main that runs right across our land. It's shown as "non-operational" but Welsh Water tell me that it will still have mains pressure water in it. They did come out and locate it for us, then the builder came back and finished the job.

We also have a friendly electrician who is happy for me to do as much of the install as I like, then he will come along, connect up and test. That's hopefully going to happen next week, so fingers crossed, we should be all go from then. I also ran in a water pipe and a duct with Ethernet, so most eventualities are covered.
 

·
Registered
Joined
·
1,064 Posts
Discussion Starter · #13 ·
Electrician came yesterday, connected it all up and tested. All my wiring tested out fine, so we now have electricity out there, and can heat and light it without running an extension cable out :)
Ethernet is next on the list, then it's almost usable, and I need to get going on all the tidying up on the outside, finish fixing down the roof, add the trims and do all the cladding.
 

·
Registered
Joined
·
1,064 Posts
Discussion Starter · #14 ·
Certificates all came through, along with his invoice, which was a very reasonable amount. His view was that I had done all the hard work and he just had to do the easy bit. Access Point is installed and connected up, and this weekend will see the carpet tiles fitted and furniture moved out, ready for it to be used next week. There's still a lot to do on the outside finish, but that can be done as and when. I'm really pleased with how it's turned out, considering that we have built it all from scratch.
 
1 - 14 of 14 Posts
Top