What size SWA cable and what Distribution boards required to shed and garden office.

[Wilf999]

Want to install a garden shed with Tumble Dryer and separate garden office building. I have run duct from side of house to where garden shed is going to be, then run another duct to where garden office is going to be. I am planning of having the office heated by electric most likely a plinth heater. All the duct is buried in concrete and will not be disturbed as under garden walls. What size SWA cable do I need to run from where it will go through wall to consumer unit to the shed and then from shed to office. Also what distribution board will I need in both shed and office. I am going get an electrician to complete final works but just trying to do most of the leg work before hand.

 

[DPG]

Want to install a garden shed with Tumble Dryer and separate garden office building. I have run duct from side of house to where garden shed is going to be, then run another duct to where garden office is going to be. I am planning of having the office heated by electric most likely a plinth heater. All the duct is buried in concrete and will not be disturbed as under garden walls. What size SWA cable do I need to run from where it will go through wall to consumer unit to the shed and then from shed to office. Also what distribution board will I need in both shed and office. I am going get an electrician to complete final works but just trying to do most of the leg work before hand.

You really need to involve your electrician now. He's the one with eyes on the job, and he will be able to do the necessary calcs.

 

[HappyHippyDad]

As above, you need to get the electrician on board now. If they feel you are a sensible person, with a high degree of DIY knowledge, they 'may' be happy giving some advice about which cables etc, and then come and do the second fix.
I personally wouldn't.

 

[Wilf999]

As above, you need to get the electrician on board now. If they feel you are a sensible person, with a high degree of DIY knowledge, they 'may' be happy giving some advice about which cables etc, and then come and do the second fix.
I personally wouldn't.

Thank you. Yes I do have a degree of electrical experience from my career is Telecoms. I've done all sorts including faulting complex AC switching systems, however I am now retired and things have moved on. The installation is at my Son's house and I want it done right. Saying that I don't want him paying for something I can legally do myself .e.g run Armoured to required positions. I will contact an electrician and get them on board, but it would be beneficial to know what size cable ( 4mm or 6mm ) and what board required in Shed and Office.

 

[loz2754]

Designing distribution circuits requires more info than what is provided here, and is beyond the scope of DIY. This is an electrician's forum primarily, although some DIY advice is permitted up to a certain level. We can't just give an answer from miles away based on scant information, and nor should anyone expect to get a free installation design service.

 

[littlespark]

What size is the duct, and how many bends?
Did you leave in a draw rope?

That might be the deciding factor in size of cable, considering the lack of flexibility of the cable…. Rather than “what size for this load”

From the size, and the distance, your electrician can work out what loads can be taken from it, and size the over current protection device to suit.
You might not get a tumble dryer AND electric space heating.

 

[Wilf999]

What size is the duct, and how many bends?
Did you leave in a draw rope?

That might be the deciding factor in size of cable, considering the lack of flexibility of the cable…. Rather than “what size for this load”

From the size, and the distance, your electrician can work out what loads can be taken from it, and size the over current protection device to suit.
You might not get a tumble dryer AND electric space heating.

Thank you... Any advice is welcome ..... The internal Diameter of the Duct carrying the Armoured cable is 50mm. It will basically go through wall from consumer unit then along wall next to drive and into back garden. It then goes vertically downwards to Duct. There is a bend as it goes horizontal underground for around 4m then another bend as it goes vertical and pops up in shed. Another cable will then go down and via another bend go 15m where it will go vertical via a bend into the office. So each cable will have 2 bends, one at either end of duct. There are proper heavy duty draw ropes in both ducts.

 

[mainline]

Thank you... Any advice is welcome ..... The internal Diameter of the Duct carrying the Armoured cable is 50mm. It will basically go through wall from consumer unit then along wall next to drive and into back garden. It then goes vertically downwards to Duct. There is a bend as it goes horizontal underground for around 4m then another bend as it goes vertical and pops up in shed. Another cable will then go down and via another bend go 15m where it will go vertical via a bend into the office. So each cable will have 2 bends, one at either end of duct. There are proper heavy duty draw ropes in both ducts.

How long is the run of swa going to be in total.

 

[Wilf999]

How long is the run of swa going to be in total.

Would say around 34m

 

[brianmoooore]

16mm2 3C SWA minimum. Saves the problem of upgrading the cable in the future, when plans change.

 

[mainline]

Would say around 34m

What is the earthing system and cutout fuse size ? As 2 core, 10 mm could suffice.

Without knowing the installation, as already said, it's guess work.

 

[littlespark]

its gonna be a squeeze getting it round the corners... even with a draw rope.

If OP has done same with telecom cables, at least he'll know how to tie a good knot

 

[brianmoooore]

its gonna be a squeeze getting it round the corners... even with a draw rope.

If OP has done same with telecom cables, at least he'll know how to tie a good knot

I've always tied on a second draw rope, attached to the first rope ahead of the knot to the cable.

 

[SJD]

its gonna be a squeeze getting it round the corners... even with a draw rope.

I had a 3-core 16mm2 SWA to draw in a 35m of 50mm inner diameter twin wall duct week before last, also with 2 bends, and was a bit worried it might not be so easy. With liberal application of Ideal cable pulling lubricant and two of us (one pulling, one pushing and lubricating) and it went in easily.

 

[littlespark]

I had a 3-core 16mm2 SWA to draw in a 35m of 50mm inner diameter twin wall duct week before last, also with 2 bends, and was a bit worried it might not be so easy. With liberal application of Ideal cable pulling lubricant and two of us (one pulling, one pushing and lubricating) and it went in easily.

So what are you saying? Plenty of lube?