adding new light and switch

Hi,

I am adding a new light and switch. I am planning to tap into an existing junction box to supply the light. Do I need to check if that junction box is the first / last one in he circuit or does it make no difference?

Thanks

What are the cables in the existing junction box connected to? if they are lights then fine, if it is sockets then you will need to use a fused spur to protect the new cable

assuming it is a lighting junction box i found this for you

http://www.diydoctor.org.uk/projects/projectselectrical.htm

To answer your original question, it makes no difference but be sure you spur from a junction box which contains a LIVE and not a SWITCHED LIVE (ie, one which is only live when another light is switched on).

NB it is not normal safe practice to spur a light off a ring main (as per previous postings - "what are the cables in the existing junction box connected to ?"....

If it IS sockets, then this is not a lighting circuit !!!. V. dangerous - eg. if you pull your lighting circuit fuse @ your consumer unit, to work on your new light in the future, it will still be live ('cos it's spurred off your ring main).

Ring main junction box will be rated 30A, cables into it will be approx. 10mm wide (measured across outer grey sheathing). Lighting circuit junction box should be rated less (I tend to use 20A) and cables will be approx. 8mm across.

HTH - Kind Regards.
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CJG, U.K