Type of conduit for short external run to garage

[roxburd]

Hi,

I've got my garage consumer unit in (mounted on a bit of MDF batoned to the wall) and the lights installed and wired up. I'm well-chuffed with the job so far.

But I just can't decide how to get the submain feed from the house to the garage. It's gotta go about 3 metres along the external wall and then into the garage. But to get into the garage it'll have to turn 90 degrees to run just a few centimetres along the garage front brickwork, if you see what I mean.

I was gonna use SWA but now I'm thinking conduit would give a more professional finish.

I could go for steel conduit like this

But it's quite expensive, especially as I'd have to get the stock, dies and guides (and work out how to use them!)

Or plastic conduit like this

But does it actually provide enough protection? It would be quite nice not to have to bother with earthing it...

Advice much appreciated.

Dave

 

[BigRobCanUFixIt]

Plastic is easier. I had a go at some steel stuff and gave up and used plastic as a DIYer.

Not sure about protection though wasnt relevant in my case.

 

[trickyd1]

I would use SWA as it will be easier to install, is mechanically protected and if it is XLPE insulated it will have a higher current carrying capacity/operating temperature than the equivelent size T+E or singles.

Not that you've got a long run but on a sub main, keeping the ZS (And volt drop) low is an important factor.

Using 3 core SWA will give you 2 earth paths and keep the ZS low on the garage circuits which could be important if you have any heavy welding kit and want to uprate CPD to type C in the case of high inrush curents tripping a type B.

Also, Trying to get 4 or 6mm2 T+E cable through conduit, either plastic or metal is a pain in the bum.

 

[Monkeh]

I would use SWA as it will be easier to install, is mechanically protected and if it is XLPE insulated it will have a higher current carrying capacity/operating temperature than the equivelent size T+E or singles.

And what accessories will he be connecting it to which are rated for 90C?

 

[trickyd1]

And what accessories will he be connecting it to which are rated for 90C?

I dont know, I'm not telepathic.

 

[Monkeh]

And what accessories will he be connecting it to which are rated for 90C?

I dont know, I'm not telepathic.

Would you like to point both of us to some 90C rated accessories for both ends of the run for which the price hike is lower than stepping up the CSA of the cable?

 

[trickyd1]

And what accessories will he be connecting it to which are rated for 90C?

I dont know, I'm not telepathic.

Would you like to point both of us to some 90C rated accessories for both ends of the run for which the price hike is lower than stepping up the CSA of the cable?

No because that's not the point at all, although I do have a feeling that henley blocks are rated at substantially more than 70deg and probably cheaper than going from 6mm to 10mm on the cable.

6mm SWA and a 32a MCB will keep the terminals within their 70 degrees. it would take about 55 amps to run 6mm at close to 90 degrees and it would take sustained loads to do this.

The extra 20 degrees temp capacity of the insulation could come in useful if it's exposed to heating from the sun on a hot day whilst carrying load where as 70deg cables may become damaged. The terminations would be unaffected temp wise as they would be in the shade.

 

[ban-all-sheds]

Would you like to point both of us to some 90C rated accessories for both ends of the run for which the price hike is lower than stepping up the CSA of the cable?

No because that's not the point at all,

Of course it's the point, you clown - you can't run the cable at 90° if what it's connected to can't run at that temperature.

although I do have a feeling that henley blocks are rated at substantially more than 70deg

A feeling?

Well that's OK then.

 

[Paul_C]

Also, Trying to get 4 or 6mm2 T+E cable through conduit, either plastic or metal is a pain in the bum.

Don't even try. Use singles, as the conduit is intended for.

 

[ban-all-sheds]

Hi,

I've got my garage consumer unit in (mounted on a bit of MDF batoned to the wall) and the lights installed and wired up. I'm well-chuffed with the job so far.

But I just can't decide how to get the submain feed from the house to the garage. It's gotta go about 3 metres along the external wall and then into the garage. But to get into the garage it'll have to turn 90 degrees to run just a few centimetres along the garage front brickwork, if you see what I mean.

I was gonna use SWA but now I'm thinking conduit would give a more professional finish.

I could go for steel conduit like this

But it's quite expensive, especially as I'd have to get the stock, dies and guides (and work out how to use them!)

Or plastic conduit like this

But does it actually provide enough protection? It would be quite nice not to have to bother with earthing it...

Advice much appreciated.

Dave

I have to say that it seems very odd that someone able to design, install and test circuits, and to be genuinely able to declare that as the person responsible for the Design, Construction, Inspection & Testing of the electrical installation, having exercised reasonable skill and care when carrying out the Design, Construction, Inspection & Testing, the said work for which they have been responsible is to the best of their knowledge and belief in accordance with BS 7671:2008 amended to 2011, and to have satisfied their LABC that they'd be able to comply with P1 has to ask questions like that....

 

[roxburd]

BigRobCanUFixIt, trickyd and PaulC,

Thanks for the input.

I have one more question. How on Earth does a forum for building, DIY, construction etc. get so many pi55y old ladies on it? I have so many morons on my ignore list now it's incredible. Is it because a lot of people have such pointless, pathetic, miserable lives that the only way they can make themselves feel big is to get high-and-mighty and pedantic on an Internet forum. It is so sad. I genuinely feel sorry for these Sad Acts. Personally, I have a life and more important things to do than try to big myself up by picking holes in people asking for help.

Anyway, thanks for taking the time to respond when no doubt you knew these pi55y old ladies were lurking just waiting to wade in waving their walking sticks. You probably have the same losers on your ignore list though so you might not know. Don't bother checking their posts out - it's just the usual confused, missing-the-point drivel.

Cheers,
Dave

 

[Monkeh]

As to the original question, yes, PVC conduit provides sufficient protection. Anything outside your house which would hit reasonably located conduit with enough force to collapse it and damage the cable is as likely to do it to steel as PVC.

However, SWA offers plenty of protection too.

PVC conduit, properly installed, will look very neat with far less effort than SWA, and so long as it's out of easy reach the protection will be more than sufficient. Don't try and pull T&E through, though.

 

[BigRobCanUFixIt]

I know what you mean......

 

[roxburd]

Cheers Monkeh,

I've just placed the order for SWA, "cable entry covers" and GripFill so the decision's made!

I am a self-build and my main concern is to make sure I do a safe job... I've used SWA before and I'm confident it will give a good, safe end result at the end of the day.

It's just such a shame a self-build can't come on here and get advice from grown-up men who know what they're doing - instead there's all this bitching and whining like a bunch of school girls... shame.

Cheers,
Dave