Garage Power Cable Upgrade

[HockeyNomad]

Hi , I recently obtained a Clack SE16C150 air compressor, and looks like it needs a 32 amp supply,

so when checking the power in my garage i found some SWA 2.5mm2 3 core cable run in from my distribution box.


so Im going to need to run some better sized cable in. The good news is its a new build and there is decent sized conduit running between my main consumer unit at the meter and the garage and the current cable is free and pulls through easily so installing some new cable should be simple. I was originally just going to get some 6mm2, 3 core SWA,

but now im thinking, should i just bite the bullet and bang some 10mm2 or perhaps even some 16mm2 cable in now to allow for any future expansion requirements? electric car charge point, maybe a bigger welder etc etc?

I keep going round in circles and changing my mind

 

[dobbslc]

Same size motor as mine and that runs on a 16amp commando plug, I did run it for a while on a normal 13amp 3 pin plug without trouble.
I've got 6mm swa down to my garage and run a lathe heater etc ok.
It's fed from the 32a kitchen ring.

 

[rtbcomp]

I'd make it as future-proof as you can afford, it won't get any cheaper.

 

[WorkshopChris]

Roughly how long will the run be?

 

[MCKDAVID]

as above, go for as big a supply cable as you can get in, and that the supplying board output will take...

compressor today, but once the toys start coming in, it'll only get worse.

 

[brightspark]

Same size motor as mine and that runs on a 16amp commando plug, I did run it for a while on a normal 13amp 3 pin plug without trouble.
I've got 6mm swa down to my garage and run a lathe heater etc ok.
It's fed from the 32a kitchen ring.

tut tut taking off the ringmain

 

[mpats]

I went for 10mm run out to the garage in conduit buried in the trench I had to run in for the oil line for the new boiler. Cost a bit more but as others have said it future proofs it. The sparky installed a 50amp supply for me to hook up to when fitting a new consumer unit.

 

[HockeyNomad]

the run is approx 6 meters in the horizontal, but a meter down from the consumer unit then 2 meters up the wall to the garage dist board. so nothing too long. ive been working it out as a 10 meter run.

 

[dobbslc]

No other way without ripping up the house! It used to be run off a 13a switch fuse spur.......
Kept popping the fuse with the heater and compressor on.
If only I'd thought about it while building the extension and run a bloody 10mm swa out from the d/b.
I was to busy doing the plumbing partitioning plasterboarding ripping up the screed floor Bov the plasterer cocked up and eventually slinging the useless builder off the job to finish it myself!
Should know better really I've wired dozens of houses over the years.

 

[Omniata]

the run is approx 6 meters in the horizontal, but a meter down from the consumer unit then 2 meters up the wall to the garage dist board. so nothing too long. ive been working it out as a 10 meter run.

10mm², you might struggle with 16mm² unless the conduit is huge...
I've a 100m roll in new colours, pity you're not closer

 

[HockeyNomad]

Thanks Ominata, Ive just been reluctanctly reading throug my yellow book and trying to put some numbers together to justify my cable choice.

According to clarke my compressor should be connected to a 30 amp supply,

I have a clarke mig welder that runs from a 13 amp plug, and a Thermal ARC 202, that would need 20A at the top end

looking at electric car charging, you can go slow off a 13A plug, but you can also get a faster charge if you install 16A or 32A plugs, so it would not be unreasonable to assume two cars charging overnight for a few hours continuously at a joint 32A in future.

now the welder will rarely be running flat out, and the air compressor would be intermitant,and both are unlikely to be running at the same time. so i can play a little bit of "diversity of demand" in my planning there, then there is the lighting circuit. and 6 double 13amp sockets on a 32A ring main, but again they are just spaced around the garage to give a choice of plug in points rater than all in use all the time.

Appendix 4 of the 17th Ed says armoured cable buried in conduit in the ground use method D for calculation of current capacity, for 10mm2 it gives me 58A and 16mm2 allows 75A the volt drops for both at the are within the allowable limits for both lighting and other. approx 1% for te 10mm2 and 0.5% for 16mm2

so im thinking 10mm2 would probably be fine but 16mm2 would give me headroom for more if i needed it. and then as you say, will 16mm2 fit in my conduit? ill need to measure tomorrow and get the cable specs and go from there i guess.

 

[Robotstar5]

Have you considered the house demands in your calculations?, electric cooker, shower, heating etc. being used while you're in the garage, will the service fuse take the load?.

 

[HockeyNomad]

Im on gas for the cookers, central heating , and showers. so i hope the 100A fuse will survive

 

[Omniata]

 

[dobbslc]

Are you sure it's not a 60amp fuse fitted?
Most are!

 

[Kayos]

You can buy the fuses on eBay....

I found a lot of new build had 80-100 fitted, and as long as it's 25mm tails and a 100a breaker someone qualified could upgrade it legally (not allowed to downgrade tho)

 

[dobbslc]

"Yeah the seal was already cut guv"

 

[The_Yellow_Ardvark]

When you run a cable run a 8 core phone/ alarm cable.

I wished I did when I ran my new cable to the garage.

 

[Kayos]

"Yeah the seal was already cut guv"

One firm I worked at basically said as long as we leave it sealed and correct it doesn't matter what we find on arrival, that did mean some interesting rewiring at times

I also in no way kept a load of crimps and seals and fuses when I left......

 

[Robotstar5]

I also in no way kept a load of crimps and seals and fuses when I left......

And they're not available on fleabay either