Metal conduit Ask questions and find answers to many subjects relating to electrics and electrical work

[efit2005]

Hi, just a couple of questions to the experts.. Does metal conduit mounted externally on an inside wall of a property have to be bonded? and can I run two wires in it touching but with different current carrying capacities i.e 1.5mm t&e and 2.5mm t&e I am thinking that it does have to be bonded and I cannot run the wires together? Is this correct?
Thanks in advance....

[sparx]

Hi, yes it must be earthed in case a conductor in it is damaged & touches metal, in which case it would become live to the touch but would not trip power off.
No problem over different cable sizes as long as all for same voltage level ie lights/ sockets wiring Ok but not say bell / alarm circuit .
regards SPARX

[efit2005]

Thanks Spark nice to have someone to clarify things!! Can I hide the bonding clamps as the conduit terminates under floor boards or do they have to be exposed? not nice looking are they!!!

[sparx]

Hi agn, It's ok to hide them as if any doubt abt earth validity a high current bond test satisfies regs ,
BW SPARX

[efit2005]

Sorry to keep on posting sparks but I might as well get all the things I am not sure about off my chest if you dont mind!!
Does the bonding for the metal conduit just link via the cpc to the nearest socket in 4mm? or go direct to the consumer unit?And can I lay wires in conduit under concrete at any depth or do they also have to be at around 600mm as if I was laying cable outside, I cant seem to see any safe zones for floors just walls
Is there any books you can recommend for wiring variations and correct procedures? Is this covered in the BS7671 wiring regs? Its just something that I would like to know about...
Thanks
Again

[sparx]

Hi agn, local bond fine, if in earthed metalic sheath(conduit) then no depth issues, unfortunately regs book only says what you must achieve but not how to do it!! Niceic publish book called 'snags & solutions' which covers a fair bit & there are dozens of books on the subject, most can be found on the web @ organisations sites such as The IEE, ECA, NAPIT, even CORGI sending leaflets to me offering such books!!
regards SPARX