Mark Gowans
New member
Hi All,
We had an electrical fault in the bathroom that I discovered having got a small shock from our towel radiator. We've located the cause of the problem, but I'm concerned the bathroom still isn't safe, so will get a qualified electrician in to resolve. However, as I'm going to have to pick someone out the yellow pages and to satisfy my own curiosity, I'd be interested in your thoughts as to the correct way to resolve this.
The current situation:
I first discovered there was a fault touching the towel radiator. A tingling sensation - like pins and needles. Ceramic tiled floor - rubber shoes. Following on from this, I got my voltage pen out and discovered that the radiator, shower head, shower controls and bathroom taps were all showing live.
The towel radiator is plumbed into the central heating, but also has an electric element, so my initial assumption was that there was a problem with the electric element and a bad earth. I turned the fuse spur to the towel raditor off and checked with a multi-meter the resistance from the towel rail to the earth on the saver socket next to the towel rail (both connected to the 'upstairs socket' ring). I put my multi-meter into 'audiable' mode to check that there was a connection - but the multimeter made an odd beeping I've not heard before and still read "1". Even with the fuse spur turned off, I was still getting the electric shock. Eventually, through a process of elimination I found the cause of the problem - a wall light in the bathroom where the securing screw had pierced the live cable. With the lights on, everything was live, lights off - everything OK again. To make things safer in the short term, I've disconnected the offending light and through reading the various forums etc have the following thoughts and questions:
1. I'm pretty certain that the lighting circuit doesn't have an earth connected back to the CU. I'm assuming therefore that the earth which is connected to the light fitting in the bathroom must somewhere in the house be connected back to the CH/HW pipework. That's a little odd though as all the pipework in the bathroom (both HW and CH) is in plastic. I couldn't think of any other way a live/earth fault on the lighting circuit was lighting up the HW/CH plumbing. Anything obvious I may have missed?
2. So now I've read up on earth-bonding in the bathroom and discovered (perhaps unsurprisingly given the age of the house) we have none in the bathroom at all. Should I expect a qualified electrician to recommend running new earth cables to the taps, shower controls etc?
3. From what I've read on earth bonding in bathrooms, this shouldn't be connected back to the CU? How does that work with a plumbed electric towel rail? Presumably that must be connected back to the CU?
4. The sockets in the house (and bathroom circuit) are on the RCD protected side of the CU, whereas the lighting is not. Am I likely correct in assuming that nothing tripped with the live/earth fault because:
4a. Lighting circuit MCB wouldn't trip because even with earth fault there was sufficiently low current draw given the only way that the CH/HW system was live would be through the water contained in it?
4b. Main RCD didn't trip because the draw was on the non-protected lighting circuit rather than on the protected ring?
5. In addition to the earth bonding, the only way to make this setup truly safe would be to rewire the lighing ring to have a proper earth and be RCD protected? Had this been the case then I presume a lighting RCD would have tripped since rather than earthing through the CH/HW, the light would have earthed straight back to the CU?
Anything else I should be thinking of / discussing with an electrician on this?
Many thanks for your guidance.
We had an electrical fault in the bathroom that I discovered having got a small shock from our towel radiator. We've located the cause of the problem, but I'm concerned the bathroom still isn't safe, so will get a qualified electrician in to resolve. However, as I'm going to have to pick someone out the yellow pages and to satisfy my own curiosity, I'd be interested in your thoughts as to the correct way to resolve this.
The current situation:
I first discovered there was a fault touching the towel radiator. A tingling sensation - like pins and needles. Ceramic tiled floor - rubber shoes. Following on from this, I got my voltage pen out and discovered that the radiator, shower head, shower controls and bathroom taps were all showing live.
The towel radiator is plumbed into the central heating, but also has an electric element, so my initial assumption was that there was a problem with the electric element and a bad earth. I turned the fuse spur to the towel raditor off and checked with a multi-meter the resistance from the towel rail to the earth on the saver socket next to the towel rail (both connected to the 'upstairs socket' ring). I put my multi-meter into 'audiable' mode to check that there was a connection - but the multimeter made an odd beeping I've not heard before and still read "1". Even with the fuse spur turned off, I was still getting the electric shock. Eventually, through a process of elimination I found the cause of the problem - a wall light in the bathroom where the securing screw had pierced the live cable. With the lights on, everything was live, lights off - everything OK again. To make things safer in the short term, I've disconnected the offending light and through reading the various forums etc have the following thoughts and questions:
1. I'm pretty certain that the lighting circuit doesn't have an earth connected back to the CU. I'm assuming therefore that the earth which is connected to the light fitting in the bathroom must somewhere in the house be connected back to the CH/HW pipework. That's a little odd though as all the pipework in the bathroom (both HW and CH) is in plastic. I couldn't think of any other way a live/earth fault on the lighting circuit was lighting up the HW/CH plumbing. Anything obvious I may have missed?
2. So now I've read up on earth-bonding in the bathroom and discovered (perhaps unsurprisingly given the age of the house) we have none in the bathroom at all. Should I expect a qualified electrician to recommend running new earth cables to the taps, shower controls etc?
3. From what I've read on earth bonding in bathrooms, this shouldn't be connected back to the CU? How does that work with a plumbed electric towel rail? Presumably that must be connected back to the CU?
4. The sockets in the house (and bathroom circuit) are on the RCD protected side of the CU, whereas the lighting is not. Am I likely correct in assuming that nothing tripped with the live/earth fault because:
4a. Lighting circuit MCB wouldn't trip because even with earth fault there was sufficiently low current draw given the only way that the CH/HW system was live would be through the water contained in it?
4b. Main RCD didn't trip because the draw was on the non-protected lighting circuit rather than on the protected ring?
5. In addition to the earth bonding, the only way to make this setup truly safe would be to rewire the lighing ring to have a proper earth and be RCD protected? Had this been the case then I presume a lighting RCD would have tripped since rather than earthing through the CH/HW, the light would have earthed straight back to the CU?
Anything else I should be thinking of / discussing with an electrician on this?
Many thanks for your guidance.
