mechanically protected

[josey]

what denotes mechanically protected when choosing cable sizes, i.e. 4mm earth for supplementary bonding, or 2.5mm if mechanically protected, would say running the cable in an attic space where access is restricted qualify as protected or does it have to be run ic trunking etc

 

[breezer]

mechanical protection is nothing to do where it is run, but what is physically protecting the cable. i.e. conduit

 

[josey]

i have run 2.5mm supplementary bonding for my light in the bathroom, because 4mm was tight in the the pull switch, it isn't run in any conduit or trunking etc, but is run in the attic where it is safe from anyone disturbing it, is this ok

 

[andy]

no. it has no mechanical protection

 

[dingbat]

Grey outer sheathing counts as mechanical protection, as in 6242Y, generally called 'twin and earth'. but the cable you are talking about is single-insulated 6491X, designed to be run in conduit, trunking, etc. So the others are right. Sadly, I've never heard of green/yellow sleeved cable with outer sheathing, which would be perfect for the job.

However, as 90% of the properties I see daily have no supplementary bonding whatsoever and 2.5sqmm is considered sufficient 'electrically' you're way ahead of the field. If this was my house I'd be happy enough with that.

 

[josey]

cheers dingbat

 

[brown-nought]

2.5sqmm is considered sufficient 'electrically'

Sorry to be picky but unless you have TT all supp. bonding needs to be 4mm. (Table 10a/b of the osg if memory is right)

 

[SwindonSpark]

Regulation 547-03-03

2.5mm^2 if sheathed or mechanically protected
4.0mm^2 is no mechanical protection.

 

[dingbat]

2.5sqmm is considered sufficient 'electrically'

Sorry to be picky but unless you have TT all supp. bonding needs to be 4mm. (Table 10a/b of the osg if memory is right)

I refer you to the answer given by SwindonSpark.

 

[Lectrician]

2.5sqmm is considered sufficient 'electrically'

Sorry to be picky but unless you have TT all supp. bonding needs to be 4mm. (Table 10a/b of the osg if memory is right)

A TT supply is not relevent when choosing the correct size supplementary bonding cables. Main equipotential bonding, yes.