lights / bonding in bathroom

[PartPapproved]

Whats more concerning is that you fail to understand the basic premise of supplementry bonding, True that the items are all earthed through their cpc's but the cpc's could be of different sizes therefore if a fault occured in say a towel rail and you were touching a radiator the fault current may flow through you and back to earth via the main equipotental bonding instead of the towel rails cpc because of the resistance of the cpc's.
The idea of the supplementry bonding is to bring all fittings to the same potential.

 

[sijaysee]

whats that got to do with the actual size of the cable though? surely you can only undersize a bonding conductor? if you use 16mm cable then thats overkill but still does the job. the bonding is just connecting those things or have i got it wrong.

 

[sijaysee]

nice to see that so many people have viewed my question...... shame that only a handfull have bothered to reply. does that mean that there are loads of numptys out there who find this whole earthing/ bonding thing a little bit hard on the head !! ive had a bottle of white now so i am just getting my head around it!!

 

[pdcelec]

i know a leccy that used to do a lot of work for me would just snip the earth off and disregard it.

and

he is a competant time severed leccy with 25 years experience

those two sentences do not correspond to me. WTF is he doing snipping the earth wires off!

 

[sijaysee]

i mean on lights.....under unit lights in kitchens and downlights

 

[Lectrician]

NEVER cut earths off - sleeve and term block them if no where to put them!! It's bad enough on the last light fitting of loop, but I see so many DIYers snip them off at EVERY downlight, loosing continuity!

 

[slippyr4]

I still don't see the point of bonding the CPC of SELV, double insulated lights. Can anyone explain a technical reason why this would be important?

 

[Lectrician]

What if they get replaced in the future?

 

[crystal ball]

nice to see that so many people have viewed my question...... shame that only a handfull have bothered to reply. does that mean that there are loads of numptys out there who find this whole earthing/ bonding thing a little bit hard on the head !! ive had a bottle of white now so i am just getting my head around it!!

No it means your question has been answered, no point in repeating information, your attitude leaves a lot to be desired, and I for one will not help you if you post again

 

[sijaysee]

sorry if i offended anyone.......espescially crystal ball.....i was just trying to say that there seems a lot of different opinions on this whole bonding thing. i do value your advice, its difficult to interperet the regs sometimes.the firm that i work for ask me to cross bond metal sinks in kitchens even though the 16th edition says that you dont need to.sockets in cupboards etc.. not against BS 7671 but advised. anyway thanks for your help

 

[ban-all-sheds]

in the end all the earths and bonding go back to the fuse board and as long as continuity is maintained then thats all that matters

No they don't, and no it isn't.

all those earths and bonding cables go back to the cu , so they are connected

No - the supplementary equipotential bonding conductor does not go back to the CU!

on the course that i did recently "domestic electrical installers"

Did you pass?

 

[sijaysee]

yes i did pass the course.....what i meant about the earths etc. is that even though you dont run the supplementary bonding cable back to the fuse board, the earth still has a path to there via the other earths....or am i wrong about that too.

 

[slippyr4]

yes i did pass the course.....what i meant about the earths etc. is that even though you dont run the supplementary bonding cable back to the fuse board, the earth still has a path to there via the other earths....or am i wrong about that too.

It most probably does, but only indirectly (either through the CPC of bonded accessories, or via lots of pipework). But that is entirely not the point. The point is to create an equipotential zone, such that every conductive part in the area is at, or very close to, the same potential.

 

[ban-all-sheds]

yes i did pass the course.

Ye Gods.

 

[sijaysee]

ban......what are you trying to say??