Cable grouping factor Trimble software

[Lc1]

Hello,
With regards to Trimble software for bs7671 cable sizing. I understand that a three phase circuit
(No neutral) is one circuit and this can be achieved by 3 single core cables. Say for a “box” we have 5 single cables in parallel per phase (15 cables total) in Trimble for grouping purposes is this treated as 5 circuits Or 15? I am a little confused because if we have three of these boxes we would need 45 cables(5 per phase,3 phases) and not 15 cables.

Thanks

 

[Spoon]

Hello,
With regards to Trimble software for bs7671 cable sizing. I understand that a three phase circuit
(No neutral) is one circuit and this can be achieved by 3 single core cables. Say for a “box” we have 5 single cables in parallel per phase (15 cables total) in Trimble for grouping purposes is this treated as 5 circuits Or 15? I am a little confused because if we have three of these boxes we would need 45 cables(5 per phase,3 phases) and not 15 cables.

Thanks

Not quite sure what you mean. Please can you clarify.
If you look at table 4C1 of the regs it states "Number of circuits or multicore cables" for grouping.
IMO 2 cables in parallel, going from one protective device to one item, is classed as 1 circuit. No grouping factors would be applied to this.
I have not used Trimble, so can't comment on how that works.
What are your thought on the matter?

 

[Lc1]

Thanks for the reply. If we have 5 single cables per phase on a three phase load (no neutral) would this be 5 circuits or 15? And if we group this with two other loads that are the same would this be 15 circuits or 45 circuits total

Thanks again.

 

[DPG]

I'd agree with Spoon - 2 parallel cables are 1 circuit, so no grouping applied.

 

[Lc1]

Thanks. Think my question boils down to table 4C5 note 5. If I have 5 cables per phase is this 5 circuits or 15 circuits?

Thanks

 

[Spoon]

Thanks. Think my question boils down to table 4C5 note 5. If I have 5 cables per phase is this 5 circuits or 15 circuits?

Thanks

The key words are "each three-phase set". You are using single conductors for the 3 phase, so 3 conductors will make a "set" or 1 circuit.

 

[Lc1]

That’s great. That’s what I thought, was confusing myself with the wording.

Thanks

 

[Spoon]

That’s great. That’s what I thought, was confusing myself with the wording.

Thanks

We all have brain fart moments mate, where we question ourselves.
Payment by cheesecake please.