I am not an electrician, but a competent DIY enthusiast – all things on the house and cars! I am sorry for the length of this post, but I have found a lot of confusion on bonding. I have tried to explain some of my misgivings in the next three paragraphs (skip if you will), but can anyone please help with the issues in my daughter’s house I descibe after that?
20 years ago when totally renovating my house, I had a proper electrician do the 1st fix (PME supply), but I plumbed and did the 2nd fix – incl. kitchen, utility, and bathrooms (2) – all copper pipework. Primary bonding was done from CU to water main to oil pipe (no gas supply). Then I was told to cross bond everything! For the kitchen and utility room it was the sink taps to the steel sinks themselves and the appliance taps. For the bathrooms it was the bath to the basin taps, the steel baths, the toilet feeds, the radiators (by drilling a hole through the radiator flange in a non critical place), the metal towel tail, and the earth on the shaver sockets.
Things change. Recently, I have built a new kitchen and utility room, this time using plastic pipe (with copper just for exposed central heating pipes). A big electric contractor did 1st and 2nd fix (2 experienced electricians, 1 lad, and firm’s contracted out Part P inspector to issue certificate) - but thankfully I managed to correct several mistakes in the lighting circuits before the ceilings were installed! Wiring to 16th edition (I have the OSG). But now there is no bonding at all in the kitchen or utility room. There is a new water main, all in plastic. Primary bonding does remain to the old copper main in the old kitchen (now converted to a study), but this is disconnected from the supply pipe and is dry.
Do these bonding provisions make any sense? Firstly, the old water main is essentially a local earth spike (which may differ from the PME earth – the supply earth loop impedance tested low – think it was 0.2ohms). I would rather have removed it altogether, and made good the hole through the damp proof and concrete floor slab. Secondly, why bond the oil pipe – which now runs in plastic conduit its full length to a plastic oil tank? Thirdly, not earthing the sinks is probably good, as there are no other exposed, well earthed objects around.
But now for my daughter’s house (which is about 20 years old), she has just had gas installed and also central heating, and I’m putting in a new kitchen.
Firstly, in the kitchen, the water supply pipe is plastic to the rising main stopcock, then copper internally. The sink taps are cross bonded back to the rising main, with a tail disappearing into the wall (presumably the primary bonding back to the CU). The new gas boiler is less than 2m of pipework from the sink. The Corgi installer cross bonded the hot and cold water pipes to the heating flow and return, and back to the gas main, but despite leaving a long tail, did not connect this to the water main – or to any circuit earth – eg. in the SFU . I have currently fixed this onto one of the bonding clamp terminals under the sink, but presumably I should solder or crimp it to the bond wire near the water main. It also seems overkill to double up on cross-bonding when the sink and boiler are so close.
Secondly, in the bathroom, plumbing to the heated towel rail is in plastic (it was too difficult to make the necessary bends through walls and joists in copper) – so it is essentially isolated. Does it need bonding – across the short lengths of plastic pipe, and then up to the shaver socket? And what is the situation with the bathroom light, extractor fan, and associated cord switch. Are the circuit earths sufficient, or should they be bonded to the bath and basin taps?
I would be very grateful if someone could help clear up my confusion?
20 years ago when totally renovating my house, I had a proper electrician do the 1st fix (PME supply), but I plumbed and did the 2nd fix – incl. kitchen, utility, and bathrooms (2) – all copper pipework. Primary bonding was done from CU to water main to oil pipe (no gas supply). Then I was told to cross bond everything! For the kitchen and utility room it was the sink taps to the steel sinks themselves and the appliance taps. For the bathrooms it was the bath to the basin taps, the steel baths, the toilet feeds, the radiators (by drilling a hole through the radiator flange in a non critical place), the metal towel tail, and the earth on the shaver sockets.
Things change. Recently, I have built a new kitchen and utility room, this time using plastic pipe (with copper just for exposed central heating pipes). A big electric contractor did 1st and 2nd fix (2 experienced electricians, 1 lad, and firm’s contracted out Part P inspector to issue certificate) - but thankfully I managed to correct several mistakes in the lighting circuits before the ceilings were installed! Wiring to 16th edition (I have the OSG). But now there is no bonding at all in the kitchen or utility room. There is a new water main, all in plastic. Primary bonding does remain to the old copper main in the old kitchen (now converted to a study), but this is disconnected from the supply pipe and is dry.
Do these bonding provisions make any sense? Firstly, the old water main is essentially a local earth spike (which may differ from the PME earth – the supply earth loop impedance tested low – think it was 0.2ohms). I would rather have removed it altogether, and made good the hole through the damp proof and concrete floor slab. Secondly, why bond the oil pipe – which now runs in plastic conduit its full length to a plastic oil tank? Thirdly, not earthing the sinks is probably good, as there are no other exposed, well earthed objects around.
But now for my daughter’s house (which is about 20 years old), she has just had gas installed and also central heating, and I’m putting in a new kitchen.
Firstly, in the kitchen, the water supply pipe is plastic to the rising main stopcock, then copper internally. The sink taps are cross bonded back to the rising main, with a tail disappearing into the wall (presumably the primary bonding back to the CU). The new gas boiler is less than 2m of pipework from the sink. The Corgi installer cross bonded the hot and cold water pipes to the heating flow and return, and back to the gas main, but despite leaving a long tail, did not connect this to the water main – or to any circuit earth – eg. in the SFU . I have currently fixed this onto one of the bonding clamp terminals under the sink, but presumably I should solder or crimp it to the bond wire near the water main. It also seems overkill to double up on cross-bonding when the sink and boiler are so close.
Secondly, in the bathroom, plumbing to the heated towel rail is in plastic (it was too difficult to make the necessary bends through walls and joists in copper) – so it is essentially isolated. Does it need bonding – across the short lengths of plastic pipe, and then up to the shaver socket? And what is the situation with the bathroom light, extractor fan, and associated cord switch. Are the circuit earths sufficient, or should they be bonded to the bath and basin taps?
I would be very grateful if someone could help clear up my confusion?
