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Andrew Smith
Andrew Smith, Plumber
Category: Home Improvement
Satisfied Customers: 3757
Experience:  City and Guilds Qualified plumber
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I am running a switched outside light from a spur which comes

Customer Question

I am running a switched outside light from a spur which comes off an extractor fan from a bathroom. There is no earth on the wire from the extractor fan just 3 core red yellow and blue. I have wired the switch and new source cables to and from the lamp correctly. I made the wrong assumption yesterday that the yellow from the 3 core was earth and wired it so. The lamp worked but there was current running through the switch plate which when I touched it cracked off the RCD in the disty board. Can you please tell me how this should be wired so it works safely
Submitted: 2 years ago.
Category: Home Improvement
Expert:  Andrew Smith replied 2 years ago.
You should run from the supply side of the fan, take the red and blue (old colours) as the live and neutral. There should be an Earth at the supply side even if it is just terminated there - this will need extending to the light.The red wire can then go in and out of a lightswitch on its way to the light.
Customer: replied 2 years ago.
Andrew, what is the yellow wire? I am on the supply side of the extractor fan and there is only the three wires, red yellow and blue? I am assuming that the yellow wire is live as well as when I mistakenly connected that to the new earth cables although the light lit up the faceplate of the switch had current running through it as I found out to my surprise. If I just use the red and blue how do I extend earth when there is none? I have earthed the switch to the backbox and used the red and blue and just ran the yellow through a connector strip but still nothing works. Any ideas?
Expert:  Andrew Smith replied 2 years ago.
The supply side of the isolator or switch.Red is permanent live (for an overrun), yellow is the switched live (to run the fan) and the blue is neutral