63amp extension lead

[iamelectric]

got a job to install a 63amp supply 3 phase commando socket , for a lighting show for an opening night , it was a metre from the D.B so i wired it in 16mm SY cable, i have now been asked to supply am extension cable for it , one male plug one female plug , about 25m long , i was thinking of using 10mm SY for it as its more manageable , but 10mm comes in at 61 amps ccc , is this ok as its an extension?

 

[GLENNSPARK]

find out what the max. Demand will be...
and calculate VD...

 

[thebigcheese]

Personally I'd use H07RNF 16mm cable. 16mm to allow for any high neutral currents from the dimming equipment and to reduce voltage drop.

 

[thebigcheese]

And how do you plan to terminate the SY correctly within the socket?

 

[Guitarist]

got a job to install a 63amp supply 3 phase commando socket , for a lighting show for an opening night , it was a metre from the D.B so i wired it in 16mm SY cable, i have now been asked to supply am extension cable for it , one male plug one female plug , about 25m long , i was thinking of using 10mm SY for it as its more manageable , but 10mm comes in at 61 amps ccc , is this ok as its an extension?

Why would you think that an extension lead can have a lower ccc than the OCPD protecting it?

 

[iamelectric]

^^^^ what do u mean i have already installed the socket

 

[iamelectric]

well its like plugin a machine in that only has a 1.5 cable into a 32amp circuit

 

[thebigcheese]

^^^^ what do u mean i have already installed the socket

As in the 63A socket (and plug) of the extension cable you are creating?

In any case a different sort of regulations apply ... BS7909 and regulation 7.3.3 states:

Cables for use outdoors and in general use should be rubber insulated and
sheathed in accordance with BS 7919 (H07RN-F or equivalent), with a
voltage designation of not less than 450/750 V (heavy duty flexible, as
defined in BS 7540-1) and resistant to abrasion and water.

NOTE 2 Thermoplastic cables are not designed for use outdoors. For example,
cables known as ‘arctic blue’, ‘SY’ are thermoplastic and are not suitable for use
outdoors.

 

[singingfraggle]

agree with big cheese H07RN is the way to go far more manageable than sy

 

[GLENNSPARK]

well its like plugin a machine in that only has a 1.5 cable into a 32amp circuit

no..
this is like suggesting that...lets say a hoover with a 1.5mm flex on a 13A fed from a ring final with 32A OPD......

 

[iamelectric]

its not for outdoor use

 

[GLENNSPARK]

what i mean to say is the current demand from any applied load should not exceed the rating of the cable attached to it...

 

[44ALLAN]

And how do you plan to terminate the SY correctly within the socket?

It's an art

 

[Toby Kuhnert]

got a job to install a 63amp supply 3 phase commando socket , for a lighting show for an opening night , it was a metre from the D.B so i wired it in 16mm SY cable, i have now been asked to supply am extension cable for it , one male plug one female plug , about 25m long , i was thinking of using 10mm SY for it as its more manageable , but 10mm comes in at 61 amps ccc , is this ok as its an extension?

16mm 3 core H07-RNF ... nice n easy

 

[Guitarist]

well its like plugin a machine in that only has a 1.5 cable into a 32amp circuit

That has a 13A fuse...The 1.5mm cable isn't connected directly to the 32A OCPD.
This has to be a wind-up.

 

[iamelectric]

a commando plug does not have a fuse in it , i have seen many extensions and machines plugged into 32amp circuits without being fused down

 

[44ALLAN]

a commando plug does not have a fuse in it , i have seen many extensions and machines plugged into 32amp circuits without being fused down

The cable will be rated above 32 amp though and the machine will have its own protection

 

[Guitarist]

a commando plug does not have a fuse in it , i have seen many extensions and machines plugged into 32amp circuits without being fused down

You seem to be missing the basics of matching cables with their protective devices.

 

[thebigcheese]

It's an art

It might be an art but I can't see how on a trailing plug and socket it can be done. Do you use special glands to bond the steel to earth?

 

[DPG]

well its like plugin a machine in that only has a 1.5 cable into a 32amp circuit

Would you use a 5A extension cable to power a 10A appliance, fed from a standard ringmain? Daz