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Lee that is helpful but the chart does not show if the cables are in free space or bunched together in one sleeve as the cable will have to be derated when bunched because of heat build up.
Edit Lee the Watts to Amps conversion has to state the voltage I know you have it done at 230VLast edited by Clive S; 26-05-2016 at 09:40 AM.
..Clive
The more you know, The better you know, How little you know
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26-05-2016 #2
OK, to clarify:
Cg represents the derating factor for grouping cables.
A cable with a current rating of 6 amp installed in trunking alongside other circuits, that's circuits not cables!, would now have a Cg value, the Cg value is 0.57.
This means the cable current rating becomes: 6 x 0.57, that's 3.42 amp.
To add to this, you should note that the grouping factors are based on assumption, the assumption that all of the cables in the group are carrying their rated current.
So, if however a cable is not going to be carrying more than 30% of its grouped current rating, that cable can actually be omitted from the group rating calculation...
...an example, if you've got lets say 6 circuits in a group of cables but 1 of those cables is known to be operating below the said 30% consistently, you can safely calculate the group on the basis that it only consists of 5 circuits.
Here are some correction factors for multicore cable:
OK Clive, how did I do?
.MeLast edited by Lee Roberts; 26-05-2016 at 10:50 AM.
.Me
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The Following User Says Thank You to Lee Roberts For This Useful Post:
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OK Clive, how did I do?..Clive
The more you know, The better you know, How little you know
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26-05-2016 #4
I know mate :), I was only having fun, my ask of "how i did" was actually sincere as I only know what I've learnt in an unformal way, im no professional.
At the same time I thought it was a good cue for providing the knowledge, as like you say those conversions need to take the operating voltage into consideration if starting from the beginning and doing your own calculations.
.Me.Me
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26-05-2016 #5
Lee, what works is not the same as what is safe and what is recommended.
https://en.wikipedia.org/wiki/Electr...United_Kingdom
That is a more realistic and better data, even if you step down one size, 1.5mm2 is what should be used. 0.75mm2 is for small desk lamps, not for motors. Then again, I know most people never really use their spindles at maximum load, so it is never really going to be a problem and in many cases even 0.5mm2 might be OK, but I think 1.5mm2 is the minimum if you want to play it safe. My 1.5kW is rated 8A and I am pretty convinced that saving on cable costs is not a good decision. Also, if you ever decide to use a vector controlled spindle you will notice that it pulls more current as well, so what is the point of under dimensioning the cable?Last edited by A_Camera; 26-05-2016 at 01:28 PM.
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