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Motion Sensor Switch Doesn’t Require an Earth but the Light Unit Does???

Postby Mr Len » Sun Apr 08, 2018 5:08 pm

Hi all,

So I’ve replaced a standard light switch and pendant bulb to have a motion sensitive switch powering a new spotlight.

Wiring it all was straight forwards, following the wiring diagram on the motion sensitive switch I supplied it with a neutral and a live as directed.

No need for an earth here per the instructions but seems odd??

I then wired my spotlight from the motion sensitive switch with a switched live and neutral again following instructions. Again, no earth but the downlight unit does have a socket for an earth.

Should I supply an earth directly from the nearest junction box to the light unit...not touching the motion sensitive switch at all or will I be ok to run without an earth?

The light unit does have an aluminium facia which would need to be touched to remove a bulb etc. That said I would turn off the mains...but the next home owned might not!!

Everything works ok, turns on and off as expected.

What do you think?

Thanks for your help!!
Mr Len
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Simply Build It

Postby ericmark » Mon Apr 09, 2018 2:19 am

We have to supply an earth with all lighting supplies since 1966, but we don't have to use them.

If the switch or lamp is marked as Class II with the double square there is no need to connect the earth wire, you can simply put the earth wire into a block connector so it feeds next item or keeps it out of way if no further items.

If not marked as class II then must connect the earth.
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Postby Mr White » Mon Apr 09, 2018 4:34 am

If it has an earth terminal it requires an earth.
You should use the earth that was there before you changed the light.
Regarding your new "switch" although it does NOT require an earth, you should leave the earth wire there, but isolated (so it can not touch anything) but it will be there for any future use.
Mr White
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