Commando Socket Cable Size

[Ash4eva12]

Hi

I Don't Touch Industrial / Commercial Electrics As I've Never Worked On The Stuff! … I Have Asked A Electrician That Does Work In This Sector (Of Who I've Never Used Before) To Wire In 2x Commando Sockets For A Customer I Have... My Question Is Are The Cable Sizes / Breakers Adequate For What's Being Installed As This Area Of Work Is Not My Forte....

1 x 16Amp 230V Single Phase 3P Commando Socket With A Cable Run (In Tray Suspended) Of 35M (He's Feeding In 4mm 3 Core SWA With A 16A MCB Type C) Coming From A 230 Volts DB

1 x 63Amp 415V Three-Phase 5P Commando Socket With A Cable Run (In Tray Suspended) Of 55M (He's Feeding In 16mm 5 Core SWA With A 63A Triple Pole MCB Type C) Coming From A 415 Volts DB

Your Views On This Would Be Much Appreciated.

Thanks!

 

[Deleted member 26818]

4mm2 armoured on tray is good for up to 35A.
16mm2 on tray is good for up to 83A.

 

[Ash4eva12]

4mm2 armoured on tray is good for up to 35A.
16mm2 on tray is good for up to 83A.

Thanks For Your Reply … So from that what he has quoted is overkill but correct...

 

[Spoon]

Thanks For Your Reply … So from that what he has quoted is overkill but correct...

Why do you say its 'overkill' ?

 

[Ash4eva12]

Why do you say its 'overkill' ?

Hi Spoon

Wasn't sure on the 16A single phase commando as to him putting in a 2.5mm2 SWA rather than 4mm2 SWA

 

[Deleted member 26818]

Hi Spoon

Wasn't sure on the 16A single phase commando as to him putting in a 2.5mm2 SWA rather than 4mm2 SWA

2.5mm2 armoured on tray is good for up to 26A.
10mm2 armoured on tray is good for only up to 62A.
Will any of the cable routes be through walls?
Perhaps the runs are quite long and the 4mm2 has been chosen to allow for volt drop?

 

[Spoon]

Hi Spoon

Wasn't sure on the 16A single phase commando as to him putting in a 2.5mm2 SWA rather than 4mm2 SWA

Could ask him why not 2.5mm. See what he says.

 

[littlespark]

Future proofing?
So if a different price of equipment is used later on.... change the 16A to a 32, upgrade the breaker... cable won’t have to be replaced as well

 

[Wilko]

Could be to meet loop impedance target perhaps, do you know the Ze?

 

[GBDamo]

Relying on reference method as described.

2.5mm would have been close on VD so 4mm probably not a bad shout.

10mm should have been ample for the the 63A.

But as always it's best to ask the guy who did the job, there may be a reason for his choices that you, and therefore we, are not aware of.

 

[Spoon]

10mm should have been ample for the the 63A

10mm2 on tray is good for up to 62A. Not really suitable for a 63A circuit.

 

[Ian1981]

Perhaps he’s been reading appendix 17 and sized them on heat losses and efficiency.
Or maybe I’m being a tad optimistic
Perhaps you should trust your electrician maybe?

 

[GBDamo]

10mm2 on tray is good for up to 62A. Not really suitable for a 63A circuit.

Well there you go, need to refer to the book more often and not rely on online calculators.

 

[Bellendian]

Bet the online calculator was using 90deg not 70deg...as normal!
Does beg the question, whats the point in 90deg XLPE, if you cant take advantage of the higher ccc as nobody appears to make accessories compatible with 90deg conductor temps!

 

[Ian1981]

Agree with the above, outside designers/consultants always state the 90 degree ccc of swa cables in their design in
my experience and they don’t like being pointed out that they are incorrect by a lowly electrical installer