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SELV lighting in zone 1

Postby Pglen » Tue Jan 13, 2009 10:05 am

I am having lights fitted above a hydrotherapy pool. The leccy is siting the transformers next to the lights in the ceiling which is 2.4m. I understood that zone 1 is limited by a horizontal plane 2.5m above the height of the pool surface. I had asked for the transformers to be placed in another room but apparently the voltage drop would mean having to run 10mm wire!!

Can anyone confirm what the regulation is and what my options are?


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Postby stoneyboy » Tue Jan 13, 2009 10:20 pm

Zone 1 under the 17th ed is 2.25m above the floor, in any case the transformers will presumably be inaccessible because they are in the ceiling void ie not in any zone.
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Postby sparx » Tue Jan 13, 2009 11:38 pm

if transformers are above ceiling then ceiling becomes extent of zone even if less than zone theoretical height, and anyway only selv would be accessible normally from below unless someone is stupid enough to remove light to get at transformer whilst standing in a bath full of water with power still on!!
Or run 10mm cable to next room as leckie suggests!
I once had to install these dreaded elv down lights in the apex of a high roofed conservatory with no room for transformers so fitted trns in adjacent room and ran 10mm single cores up and back in frame of conservatory.
Can't for the life of me understand why anyone would fit these elv abhortions when they cost more, are less reliable and more difficult to install than 230v version & cost more to run due to transformer losses;
and require special dimmers if required to dim
regards Sparx
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Postby sparx » Fri Jan 16, 2009 5:48 pm

Just a quick rejoiner, Stoneyboy would be correct if it where a bath or shower 2.25 mtrs from floor would be limit of zone, but as you are calling it a pool then it becomes 2.5m from top edge, as for a swimming pool. Perhaps with hindsight you are fitting a hydrotherapy bath!!!...
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Postby ericmark » Fri Jan 16, 2009 9:48 pm

Not sure what hydrotherapy is but 701.1 Scope These regulations do not apply to locations containing a bath or shower for medical treatment, special requirements may be necessary.
So they may not be covered by BS7671 at all?

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