10mm SWA or 16mm SWA for garage conversion?

[poolballboy]

Evening,

I am currently doing a garage conversion and need to run a power cable from the house fuse board to the garage. The garage will be a standalone 2 bed holiday let. There will be gas on site so will reduce the dependency on electric. I am having the trench dug next week and wondered what size 2 core cable to run in the trench, 10mm or 16mm, the run will be +/- 60m? Please can anyone advise?

Thanks

Andy

 

[Robin0577]

The size your electrician specifies. If you don't have an electrician on board yet then put in a duct like this https://www.tlc-direct.co.uk/Products/FXKVR75.html with a draw rope in it, buried at least 50cm deep, keeping bends to an absolute minimum. Put in warning tape https://www.tlc-direct.co.uk/Main_Index/Necessities_Index/Electric_Cable_Below_Tape/index.html above the duct, and take photographs at every stage of the job to show the electrician and/or building control what you've done. The photos should include a ruler or tape measure to prove the depth of the trench.

While you're at it, put in a second, smaller duct for phone/security/data/TV cables.

Oh, and bung up the ends of the duct while work is going on so it doesn't end up full of mud/concrete/rubble.

 

[sparkwright]

That's quite a long run of cable, so voltage drop may or will mean affect the size of the cable.

What loads will be in the garage conversion? Electric shower, cookers, sockets, lights, water heater etc?

At 60m, you may well NOT want to bother running ducting, as it will be a tiresome job.

 

[chivers67]

What "Two core" why not Three Core? If it's that long you may as well run a 25mm!

 

[flameport]

Likely that the real solution is a new DNO supply, rather than extending an existing one over that distance.

 

[SUNRAY]

At 60m, you may well NOT want to bother running ducting, as it will be a tiresome job.

Why tiresome ???

 

[conny]

Why tiresome ???

Because it's a long distance to dig by hand with a spade. LOL
Obviously with a mini digger and trenching tool fitted it would be fairly easy, but only so long as you know where any 'hidden' underground pipes, drains cables are of course.
If the garage/holiday let is to have a water supply as well then you have to go to 750mm depth for the supply pipe.

 

[SUNRAY]

Because it's a long distance to dig by hand with a spade. LOL
Obviously with a mini digger and trenching tool fitted it would be fairly easy, but only so long as you know where any 'hidden' underground pipes, drains cables are of course.
If the garage/holiday let is to have a water supply as well then you have to go to 750mm depth for the supply pipe.

But presumably the trench needs to be dug regardless, so my question is why is the duct tiresome?

 

[sparkwright]

But presumably the trench needs to be dug regardless, so my question is why is the duct tiresome?

You have to thread 60m of heavy cable through the ducting. After so many metres, it seems to get harder.

Easier to chuck the cable directly in the trench, and place an empty duct over the top, with a rope in it, for future use.

I'm not totally serious, and I probably would put the cable in the duct, if only for repairs or alterations to the cable.

No requirement for duct, but always useful if anything should happen.

 

[SUNRAY]

You have to thread 60m of heavy cable through the ducting. After so many metres, it seems to get harder.

Cor blimey 16mm² hard?

 

[winston1]

What "Two core" why not Three Core? If it's that long you may as well run a 25mm!

Really. Whole houses are run on smaller cable than that.

 

[chivers67]

I think he'll want 16mm minimum to allow for volt drop over that length but we're peeing in the wind as he hasn't said how much power and what circuits will be inside the Holiday let.

 

[JohnW2]

Really. Whole houses are run on smaller cable than that.

They are - but, I would have thought, very rarely a cable which is 60m long (from DNO's distribution main).