Supply feed to holiday home

[sclarkin]

Hi all,
Customer wants to install a holiday home in one of their fields 300m away. They want a 63amp supply so I just ??
Quick calc comes out at 95mm swa not sure what size drum it would need. I suggested they should ring sse and get a quote for a new supply of off the power pole at the house
Can anyone think of install ideas
Thanks

 

[Spoon]

Prysmian cable calc online

What cable type?

 

[Spoon]

I got exactly the same answer with Procerts app btw.

Again, what cable type?

 

[sclarkin]

Again, what cable type?

SWA buried 90c

 

[Spoon]

SWA buried 90c

Just make sure that the devices that this cable is connected to are also rated at 90c then all is well.

 

[sclarkin]

Just make sure that the devices that this cable is connected to are also rated at 90c then all is well.

Yeah that comes up alot

 

[pc1966]

Just make sure that the devices that this cable is connected to are also rated at 90c then all is well.

In this case you can safely ignore the 90C rating as the size of the cable is down to volt drop.

For example the 95mm XLPE 90C SWA cable is rated at 239A (Table 4E4A, method D) so at 63A your I2R loss is just over 14 times lower, so your table values for 20C ground -> 90C insulation rise scaled to that will be of the order of 5C (i.e. cable runs at 25C is in duct in ground at 20C).

Wrangling and terminating 95mm on the other hand is a serious issue!

 

[sclarkin]

In this case you can safely ignore the 90C rating as the size of the cable is down to volt drop.

For example the 95mm XLPE 90C SWA cable is rated at 239A (Table 4E4A, method D) so at 63A your I2R loss is just over 14 times lower, so your table values for 20C ground -> 90C insulation rise scaled to that will be of the order of 5C (i.e. cable runs at 25C is in duct in ground at 20C).

Wrangling and terminating 95mm on the other hand is a serious issue!

Interesting.
Yeah been a long time since I've worked with 95mm and above. Sure I can dig out my old club hammer to help with termination ?

 

[brianmoooore]

Wrangling and terminating 95mm on the other hand is a serious issue!

I actually have 95mm2 SWA as a submain to my own house. Not chosen because it was required, but because a supplier delivering a reel to a job I was doing damaged the cable, leading to me rejecting it.
Replacement was delivered to site, but the damaged cable not removed, so an undamaged section ended up feeding my house.
It terminates into a surprisingly small galvanized adaptable box with crimped lugs on the conductors. 25mm2 tails are also fitted with crimped lugs, and the pairs of lugs bolted together before the box was resin filled.

 

[pc1966]

Interesting.
Yeah been a long time since I've worked with 95mm and above. Sure I can dig out my old club hammer to help with termination ?

I don't normally work with anything big, so last year when I had a job that might need it I bought just 1m of the planned cable to get a feel for what I might be getting myself it for and to check the glands would fit properly, etc.

Can't imagine what the postman though of it!

 

[pc1966]

It terminates into a surprisingly small galvanized adaptable box with crimped lugs on the conductors. 25mm2 tails are also fitted with crimped lugs, and the pairs of lugs bolted together before the box was resin filled.

Interesting, though in my case the tools I have only crimp up to 50mm so would have to think about borrowing/renting something for above that.

The likes of the Al cable are sectorial, presumably you get special quadrant shaped crimps for them?

If cable cost were the driving factor for the OP I would be looking at the 70mm 4-code aluminium option with some sort of resin filled termination, probably going to 16mm 4-core copper and then finally pairs of the 16mm to terminals indoors so you can IR test each core separately.

Based on the illustration here, for minimum inductance factor I would pair opposite cores, so brown & grey for L and blue & black for N for the cable:

https://www.clevelandcable.com/media/pdfs/BS5467-PVC-aluminium-conductor-mains-cable.pdf

While it might need to be TT if a caravan like metal building, for a house it will probably need to be considered the same for supply Zs being too high so still a delay RCD up front at the outbuilding CU. However, the data for 4-core 70mm copper has the armour down as 131mm CSA so above the 10mm copper equivalent needed for extraneous bond TN-C-S so could supplement any local earth rod OK and keep the Zs down far lower than just a rod or two.

I guess it would meed the end of cable Zs for a 63A fuse on 5s disconnection but not checked that, really would need a check for the actual cable armour R2 and supply Ze.

 

[pc1966]

If cable cost were the driving factor for the OP I would be looking at the 70mm 4-code aluminium option with some sort of resin filled termination, probably going to 16mm 4-core copper and then finally pairs of the 16mm to terminals indoors so you can IR test each core separately.

Really it should be 5-core 16mm, so there is a copper CPC linked to the major cable's armour to keep the overall path above 10mm if TN-C-S is considered (or even just marginal on the supply fuse end-of-cable Zs limit).

 

[sclarkin]

Thanks all for the responses.
It's a shepards hut in one of their fields.
The farm is already a tt supply

 

[Spoon]

I'd like to see the process of laying out 300 meters on 95mm cable. Doesn't look like fun.

 

[pc1966]

I'd like to see the process of laying out 300 meters on 95mm cable. Doesn't look like fun.

Yes, better to fight an arngy python that have been overdosing on ------...

 

[Mike Johnson]

Easy, tie one end to the Combine Harvester, put the reel end on the forks of the Tractor and pull. ?