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Discuss earthing in the Electrical Forum area at ElectriciansForums.net

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ample current

Regular EF Member
I went to a house today to look at some work in this guys bathroom. He wants his ceiling replastered and downlights put in instead of the single luminaire that is already there. not sure if the upstairs lights are earthed, (1940's house) i will take a closer look next time i visit. If not was going to run an earth wire to the MET. from the downlights. or can you get them that dont require an earth.
Am i right in saying the lighting circuit should have an rcd fitted if the luminaire is changed to down lights.
I took a quick look at his CU (fuse board with wire fuses) while i was there and the earth connections look dodgy to say the least, i should have took a pic, the main earth (TN-S supply) looked like it was hanging on by a thread and tha cable looked no bigger than 4mm max. Is it the DNO,s responsability to make this a good connection.I know the rest is up to the home owner. I got the impression the home owner did not want to spend too much money. He said the house was rewired in 1970 something


Scouser and Proud of It
Respected Member
any work done in a bathroom needs RCD protection. gthe earthing and bonding need to be checked and if necessary, upgraded.

Dave 85

If your gonna run an earth wire why not a new circuit, or were you gonna clip outside? And yes RCD. Im not 100% sure about unearthed circuits with no metal accessories but personally I'd never work on one.

SirKit Breaker

It always makes me laugh when i see "They dont want to spend much". Nobody ever does want to spend on the basics because it can't be seen, well not till it all catches fire or someone gets injured anyway. This is not a pop at the OP, it is directed at the customer.

Reminds me of a job i did a year or two back, they had a cellar conversion done, and it cost about £30,000 by the time they had finished. I advised that the house needed a rewire, and that was before going anywhere near it with an IR tester, they declined my offer, and i wired the cellar into a new CU, splitting the supply with a Henly. a short while after i had completed the work, they called me as they were having problems with fuses blowing, i did an IR test on RFC and got a reading of about 25 ohms. I declined the offer they gave me to rewire the house, cos it was going to be a proper ball ache with the cellar and loft conversions. I hate to say it,
but i told them so, and i could have saved them a fortune.


PS i meant to add, the cellar was done as a complete new install, not using any existing wiring that was shot.
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Depends if the earth is a pukka DNO earth or a dodgy strap onto the lead with a clip, had a dodgy one today where a sparky had made his own earth from the lead sheath. If its the DNO earth they're obliged to maintain it, if you earth loop it and find its over 0.8 at the incomer ring the DNO


Electrician's Arms
1. Earthing and bonding must be up to scratch before any work takes place. Test Ze and make sure main bonding is in place.
2. Only class 2 fittings can be used if there is no cpc in lighting circuit, Most downlights are class 2.
3. lighting circuits with no cpc must be fitted with a 30mA RCD.


Electrician's Arms
A bathroom is a special location and not really something you should be working on with "advice from other people". While I'm sure that most forum members are professional electricians, many are diy'ers who could tell you anything. I would advise reading the regs carefully yourself in this instance.
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