Mike M:

Guys,


BS7671:2018 is classing cables extra low voltage (ELV) as an operating voltage not exceeding 50Vac or 120V ripple-free dc.


BS7671 goes on to further categorize ELV cables into SELV, PELV, FELV.


For single core green/yellow insulated equipotential bonding cables lets say originating from an earth bar and bonding some structural steel work, are these classed as FELV under BS7671:2018 ?

I read a comment that it is possible to have earthed SELV, which is not possible as it ceases to be SELV and becomes FELV.

Sparkingchip:

Mike M:

Guys,


BS7671:2018 is classing cables extra low voltage (ELV) as an operating voltage not exceeding 50Vac or 120V ripple-free dc.


BS7671 goes on to further categorize ELV cables into SELV, PELV, FELV.


For single core green/yellow insulated equipotential bonding cables lets say originating from an earth bar and bonding some structural steel work, are these classed as FELV under BS7671:2018 ?

The original question.

 

Sparkingchip:

Sparkingchip:

Mike M:

Guys,


BS7671:2018 is classing cables extra low voltage (ELV) as an operating voltage not exceeding 50Vac or 120V ripple-free dc.


BS7671 goes on to further categorize ELV cables into SELV, PELV, FELV.


For single core green/yellow insulated equipotential bonding cables lets say originating from an earth bar and bonding some structural steel work, are these classed as FELV under BS7671:2018 ?

The original question.

 

 

It states, in bold text to emphasis it, insulated cable and insulated cable has a voltage rating.


Moving the goal posts to try and score points with Ah! Yes, but comments?


The insulated cable has to be rated for the highest voltage that is likely to be present, which in a circuit supplied by a FELV transformer will be the voltage of the primary circuit not the secondary circuit; how would even be vaguely possible to consider a main equipotential bonding conductor FELV when it could be presented with the highest voltage within the installation?

 

OMS:

Mike

Andy in my opinion I would agree and I would say the current is the relevant factor. For example we frequently use a 10mm2 bare un-insulated aluminium cable/tape under BS EN/IEC 62305 to conduct millions of volts safely to ground during a strike.

 

I thought BS EN 62305 indicated that aluminium components of a LPS should be a minimum of 50mm2 if solid round or stranded round and 70mm2 if tape.


Did you mean 10mm diameter (allowable as a reduction for short air terminations) or exceeding the nominal 8mm diameter of circular aluminium of 50mm2 CSA 


Regards


OMS

 

Mike M:

 

OMS:

Mike

Andy in my opinion I would agree and I would say the current is the relevant factor. For example we frequently use a 10mm2 bare un-insulated aluminium cable/tape under BS EN/IEC 62305 to conduct millions of volts safely to ground during a strike.

 

I thought BS EN 62305 indicated that aluminium components of a LPS should be a minimum of 50mm2 if solid round or stranded round and 70mm2 if tape.


Did you mean 10mm diameter (allowable as a reduction for short air terminations) or exceeding the nominal 8mm diameter of circular aluminium of 50mm2 CSA 


Regards


OMS

 

Lightning equipotential bonding for metal installations BS EN 62305-3 table 9