Just want to check when a commando socket is rated at 63A, (4 pins and earth) that's 63A total, not per phase. I've read a few data sheets and this point isn't clear.
63A 3 phase socket
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Per phase.
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Thar's a big un. What's going to plug into it?
Just wanted to check Rob, I don't do much 3 phase work, so I'm a bit rusty in this area. I've got a customer who tells me he needs a 20kW supply, but somehow has got in his head he wants a 63A socket on a 63A MCB and cables to suite 63A per phase. (I think he is confused) Now 20 kW is roughly 80Amps, cable run is 45m clipped direct to wall. Now rough calculations would suggest a 6mm cable would suffice for the load. I am planning to install 10mm, table 4E2A says 71A (total) for 4 core. THe load is to charge batteries, so I'm working on the basis the load will be quite steady for quite some time and larger cable cost will be outweighed by reduced energy loss and wasted leccy. Now if what he really wants is 20kW per phase, that's a bit of a larger cable :^O
batterys
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I make out that 20kW load to be around 32amp a phase based on 400V. Although I don't know what the pf of the load is.
10mm will be ample, dependent on your Zs requirement.
10mm will be ample, dependent on your Zs requirement.
OK, customer reports that it is 23kW total load, so I make that about 42Amps total or 16A per phase, so we would be happy on a 20A MCB and a 20A commando socket with a 10mm 4 core XLPE SWA rated at 73A, 6mm is rated at 53A according to the big yellow book, so a l ittle undersized though it would probably work fine!
do they do a 20A commando socket?
I have only see 16A,32A,63A,125A ones after that its 200A,250A,and so on but there not commando
I have only see 16A,32A,63A,125A ones after that its 200A,250A,and so on but there not commando
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no, as I've just found out.
I = 1000 × P / (√3 × PF × VL-L )
does formula give amps per phase or total?
does formula give amps per phase or total?
That gives amps per phase. The route 3 take care of that.
W / (√3 * PF * V*eff)
Efficiency can be taken as 1 if the load is purely resistive, i.e not a motor.
23000 / (√3 * 0.95 * 400 * 1)
W / (√3 * PF * V*eff)
Efficiency can be taken as 1 if the load is purely resistive, i.e not a motor.
23000 / (√3 * 0.95 * 400 * 1)
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Ok pinched the figure from Doncaster cables 23kW / 41.5A 6mm cables in XLPE.
so tables at back of big yellow book give amps per phase for 3/4 core cables or amps total?
so tables at back of big yellow book give amps per phase for 3/4 core cables or amps total?
That’s amps per phase. Also which table are you looking at? 70 or 90c cables?
you should be using 70c cable unless the terminations can take 90c
Thought so but mislead by a post on another forum.
planning on using 90c cables - smaller. Not heard of any restrictions from terminations before.
planning on using 90c cables - smaller. Not heard of any restrictions from terminations before.
XLPE can run at 90 but most terminations are limited to 70 so youre stuck with the weakest point
You should be using 70c cable. 90c has a higher operating temp hence the requirement for terminations within accessories being able to withstand the higher temps.
If you look at the 90c table in the BYB there’s a caveat about temps.
fair enough, but cable is oversized anyway to reduce voltage drop and energy losses
oversize is fine, but you stil need to use the 70 degree charts and not the 90 degree unless your terminates are designed for 90
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