Cable Size for 630A
- Thread starter dw3101
- Start date
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How far is the run?
Nature of the load?
Do you want the easy way or harder way?
Nature of the load?
Do you want the easy way or harder way?
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Greater than 400mm thats for sure.
Amtech only does upto 400mm, so can't use that. Will dig regs out later maybe.
As it is the main cable from gen inwards, it may be sized not only for current rating, but also to have a negligable volt drop - this is often the case for a genset. You want the volts to start dropping at the changeover switch ideally.
In your opinion, is the cables specced too large or too small?
The earth should be atleast half the size of the phase/neutral, but can be calced. For 20m, would it be worth calcing? Also, the neutral cable from gen to changeover switch could be a CNE conductor is you so wish, splitting out at the changeover switch. Seen this done on some installs. It has been questionned before, but no definitive answer has been given. I have always run a seperate earth conductor myself in these situations.
Amtech only does upto 400mm, so can't use that. Will dig regs out later maybe.
As it is the main cable from gen inwards, it may be sized not only for current rating, but also to have a negligable volt drop - this is often the case for a genset. You want the volts to start dropping at the changeover switch ideally.
In your opinion, is the cables specced too large or too small?
The earth should be atleast half the size of the phase/neutral, but can be calced. For 20m, would it be worth calcing? Also, the neutral cable from gen to changeover switch could be a CNE conductor is you so wish, splitting out at the changeover switch. Seen this done on some installs. It has been questionned before, but no definitive answer has been given. I have always run a seperate earth conductor myself in these situations.
B
breezer
many years ago, we had to run a cable for a bunch of 3 phase heaters on a production line.
I was an apprentice at the time, i cant remember the size now but the size required was so big it was physicaly impossible to do it. (high up in the ceiling of a factory fixed to the buildings steel work)
solution run 2 smaller cables
I think we averaged about 1 yrd / hour pulling each one in
I was an apprentice at the time, i cant remember the size now but the size required was so big it was physicaly impossible to do it. (high up in the ceiling of a factory fixed to the buildings steel work)
solution run 2 smaller cables
I think we averaged about 1 yrd / hour pulling each one in
Multicore armoured XLPE -
300mm² 4 core just falls short at 628A so 400mm² with a VD of 2.8V @630A assuming worst case scenario as regards self inductance of cable.
300mm² single core, Al armouring, flat and touching 3.5V drop @ 630A
Both based on 20M.As has been said before you could do the adiabatics or just go for the 1/2 sized CPC
300mm² 4 core just falls short at 628A so 400mm² with a VD of 2.8V @630A assuming worst case scenario as regards self inductance of cable.
300mm² single core, Al armouring, flat and touching 3.5V drop @ 630A
Both based on 20M.As has been said before you could do the adiabatics or just go for the 1/2 sized CPC
At last, a proper DIY question (not) ! 
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