Swa/pvc cable size

[Engineer54]

Not saying theres anything wrong with tables, just saying you dont use the 8 - 1 ratio

Only when i think there's a need to calculate. More a case i think, of getting used to the numerous installations of SWA cables on the bigger projects. You get, what i can only describe as an instinct or gut feeling that there could be a problem with a particular cable run. Most of the time, the cable will still comply, ....but Just!!! But still happy that you did the calculation to prove that it warranted that extra effort... lol!!!

 

[Chr!s]

I dont have johns chart, i use the manufactures info or GN8.

My earlier posts were trying clear up the fact that there is a difference between the copper equivalent for steel, when calculating for a cpc and for that of a bonding conductor.

 

[Deleted member 26818]

Yes the requirement for a CPC is based upon the withstand capabilities of a material for a short duration at a high amperage.
Whereas for bonding conductors where PME conditions apply it is the withstand capabilities of a material for what could be very long periods at unknown amperages.

 

[Engineer54]

Chris,

I found this in the Sticky threads on this subject. It is the paper John Shepherd wrote that includes the table that Spin and i use a a good rule of thumb for guidance on the SWA CSA etc....



Using the armour of SWA.pdf

 

[Chr!s]

Whereas for bonding conductors where PME conditions apply it is the withstand capabilities of a material for what could be very long periods at unknown amperages.

Copper equivalent should be used for all bonding regardless of earthing arrangement

 

[Deleted member 26818]

Copper equivalent should be used for all bonding regardless of earthing arrangement

Not in order to comply with BS7671.

 

[Chr!s]

Not in order to comply with BS7671.

Not in order to comply with BS7671.

Not with you there spin, bonding need to meet requirements of 544, look at the note at bottom of table 54.8

This requires copper equiverlent

 

[Deleted member 26818]

Yes, Table 54.8 is only applicable where PME (TN-C-S) conditions apply.
For TT, and TN-S sytems, there is no requirement for a copper equivalance.

 

[Chr!s]

For TT, and TN-S sytems, there is no requirement for a copper equivalance.

Read 544, 1st paragraph last sentence, affording equivalent conductance

 

[Deleted member 26818]

That applies where the bonding conductor is required to have a CSA greater than 25mm².

 

[Chr!s]

That applies where the bonding conductor is required to have a CSA greater than 25mm².

It may read that way, GN8 gives a clear explanation and equation for the requirements of bonding, page 41

 

[Lister1987]

Chris,

I found this in the Sticky threads on this subject. It is the paper John Shepherd wrote that includes the table that Spin and i use a a good rule of thumb for guidance on the SWA CSA etc....



Using the armour of SWA.pdf

Anyone got acopy of the John Peckham table? Could do with seeing if thr one I've been given is correct.

 

[nicebutdim]

Anyone got acopy of the John Peckham table? Could do with seeing if thr one I've been given is correct.

Welcome to the forum, Lister

 

[Lister1987]

Welcome to the forum, Lister

Got to dabble in some thread necromancy from time to time

 

[Eddy Currents]

Anyone got acopy of the John Peckham table? Could do with seeing if thr one I've been given is correct.

Use SWA as CPC, a guide to the acceptability of steel wire armour use as CPC.

SWA as the CPC? In most case it is fine to use the SWA as a CPC.

gadsolutions.biz

 

[Lister1987]

Use SWA as CPC, a guide to the acceptability of steel wire armour use as CPC.

SWA as the CPC? In most case it is fine to use the SWA as a CPC.

gadsolutions.biz

As I Understand it, this is thr incorrect data and not John's information.

 

[Eddy Currents]

I'm not sure 100% but it does state

"Many thanks to John Peckham for authoring this"