2 dis boards off one cable?

[Greengo1990]

hi there. Starting a job soon to install 2 6 way dis boards in outside cabinets. At the bottom of the hill there is a Scottish power main switch installed. I was wanting to run a swa from there to first cabinet then run another swa from cabinet to other cabinet. From SP to first cabinet the cable run is 100m and from 1st cabinet to 2nd cabinet cable run is 190m. Loading for each cabinet is 8kw each. Will this be ok to loop supply in some sort of joint box with appropriate connectors
Thanks

 

[ipf]

Too many unknown factors. You're asking for assumptions, although, for starters have you thought about the required cable size due to volt drop.

 

[Leesparkykent]

If I was designing this I would probably have over current protection for the second distribution circuit in the 1st cabinet. that's quite a load over 200 meters. Have you carried out any calculations?

 

[ipf]

If I was designing this I would probably have over current protection for the second distribution circuit in the 1st cabinet. that's quite a load over 200 meters. Have you carried out any calculations?

Agree...if the connections will take the cable size with another 190m to run

 

[HandySparks]

I don't see a problem with more than one DB on a distribution circuit, subject to the usual cable calcs. Too many circuit breakers in series will lead to lack of discrimination in the event of a fault.

 

[Wilko]

If I've understood correctly, probably 50mm cable which is over £1k per 100m. Well worth having a proper design done by an expert (not me )

 

[The Ghost]

Would it not cut down the total cable run by running in two supply cables?

 

[ChrisElectrical88]

If this was me, I would run a cable to cab1, install a small 100A bus bar chamber, then a switch fuse off this for the board in cab 1 and then a switch fuse for the Sub main up to cab 2.

What size cable have you calculated out of interest?

 

[ChrisElectrical88]

100A Busbar Chamber Grey | City Electrical Factors - http://www.cef.co.uk/catalogue/products/46105-100a-610mm-width-busbar-chamber-grey

 

[Greengo1990]

H

If this was me, I would run a cable to cab1, install a small 100A bus bar chamber, then a switch fuse off this for the board in cab 1 and then a switch fuse for the Sub main up to cab 2.

What size cable have you calculated out of interest?

hi Chris. For the 190m run a 50mm swa

 

[davesparks]

H

hi Chris. For the 190m run a 50mm swa

What about the first leg?

 

[davesparks]

If this was me, I would run a cable to cab1, install a small 100A bus bar chamber, then a switch fuse off this for the board in cab 1 and then a switch fuse for the Sub main up to cab 2.

What size cable have you calculated out of interest?

You could run in to discrimination issues with that arrangement leading to the supply to the first cabinet being oversized unnecessarily.

 

[Greengo1990]

You could run in to discrimination issues with that arrangement leading to the supply to the first cabinet being oversized unnecessarily.

For the first cabinet 25mm swa

 

[Bobster]

What's the Ze?

 

[Greengo1990]

What's the Ze?

0.23ohms

 

[Bobster]

I'd take a look at the max Zs, if you're feeding from an MCB you may have to up the cabe size just to meet that

 

[Greengo1990]

I'd take a look at the max Zs, if you're feeding from an MCB you may have to up the cabe size just to meet that

I am going to be feeding from a fused isolator

 

[davesparks]

For the first cabinet 25mm swa

Eh? Your first leg is half the size of the second leg, that sounds a bit odd to me.

 

[ChrisElectrical88]

You could run in to discrimination issues with that arrangement leading to the supply to the first cabinet being oversized unnecessarily.

True, but I would be adding a bit extra on anyway for future useages with those sorts of runs!

 

[davesparks]

True, but I would be adding a bit extra on anyway for future useages with those sorts of runs!

Just adding a bit on doesn't guarantee discrimination