OP
MDJ
Also good practise IMO, local isolation for a moving part, maybe not regs, not sure about that will have to check, but in anycase good practise
Discuss Smoke alarm 3rd core, WHY ? in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net
No......you need to go from the switch to a TP fan isolator then the fan.
Common - perm live at fan isolator (brown)
S/L - S/L at fan isolator (black....remember to sleeve)
Neutral - Neutral (gray......remember to sleeve)
Then wire from the isolator to the fan!
Failing that......rtfm.....or call a professional spark
Put simply, the only time a 3 pole isolator is required is if the manufacturers instructions specify that one must be fitted.
Every electrical circuit must have a point of isolation. Every electrical circuit can effectively be isolated by use of the main switch.
Local isolation is a made up term and is found nowhere in BS 7671. 'Readily accessible means of switching off' which does appear all over the BGB, is open to interpretation.
These are the main points I try to make in that post, is there anything specific you need clarification of bud?
it might not be in the wiring reg's, but the building reg's says that "an extractor fan supplied from a lighting circuit for a bathroom without a window should have it's own means of isolation, as otherwise replacement or maintenance of the fan would have to be carried out in the dark. an isolation switch for a fan with an overrun facility will need to be triple-pole (switch wire, line and neutral), and must be installed outside of zones 0, 1 and 2."
however an isolation point is required?
No it doesn't, what you have posted there is a direct quote from The Electricians Guide To The Building Regulations. This book is as it says... a guide. It is simply a book, written by an individual and is not statutory in any shape or form.
yep, i'll concede to that. even though it's non statutory it's still good advice, but i accept your point.
what i will say is that, whilst you may be correct about the lack of any hard and fast rules regarding isolators, as the installation designer i must make an assessment of the type of equipment that is being installed and who is going to be using it. extractor fans have permanent lives, motors and moving parts; there is every possibility that something could go wrong at a later date which would require a competent person to carry out repairs. it's not beyond the realms of possibility that these repairs might need to be carried out in less than satisfactory light conditions and because of this, i believe it's good practice to provide isolation from a point other than the fuse board.
also, it might be acceptable to use the mcb for isolation in a tn installation, but what about a tt? i'd want both line and neutral disconnected. it's obviously not ideal to isolate the entire installation, so a fan isolator is the perfect solution.
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