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I've read a bit about earthing on the forum and it has been very helpful - it is one area the DIY books are poor on. I would be grateful if someone could clarify a few points:
I live in a block of flats and none of my pipework etc is cross bonded. I assume (?) that the main gas and water pipes supplying all of the flats are earthed where they enter the building (about 80 feet from my flat). Do I need to attach earth clamps to them where they enter my flat and link them back to the CU?
Which brings me to my next point - linking anything back to the CU is hard work (at least trying to do it neatly) because the floors are concrete and all cabling is run in the half inch space above the plasterboard ceiling. I have managed to lead a 10mm earth wire from the CU across into the void space where all of the service ducting, pipework etc is located. I put a 4-way earthing connector block on the end of this 10mm cable and used it to supply an earth to the new light fitting I put up in the bathroom. (I know the lighting circuit should have an earth but the cabling seems to be in good condition [it is 1960s] and given the problem feeding cables a total rewire of the lighting circuit would be a pretty big job). Can all of my bathroom and kitchen cross bonding be linked back to this 4-way connector block, and thus back to the CU through the one 10mm cable?
In the kitchen I was planning to cross bond the sink, cold and hot pipes (what about the gas pipe?) and link them back to the earth block in the void. Does it matter where I attach the earth clamps to the pipes, ie under the kitchen sink or about 2 feet from the sink on the other side of the wall in the void space? This is pretty much the point at which the cold and gas pipes enter the flat.
In the bathroom, I was planning to connect together all cold and hot pipes supplying toilet, sink, bath, shower, and earth the bath itself and then connect these back to the 4-way earth block. All of these pipes to toilet sink etc come through the wall from the void - can I put the earth clamps on the pipes on the void side of the wall (neater looking job), or do they all have to be on the bathroom side of the wall (there would only be about 6 inches difference).
[Incidently, looking at pictures of equipotential bonding in bathrooms in books, although the toilet, sink and bath are all fed off one cold water pipe via T pieces, the piece of pipework leading to each of them has its own earth connection - why can't you just earth the pipe once? Is it because you can't assume that the solder/compression fittings used to T off the main pipe will provide a low resistance path? ]
Am I ok using 4mm for all of this (I have seen some say 6mm)? Does it definitely have to be an unbroken length of cable with the earth clamps threaded on where in the insulation is stripped off?
Lastly (sorry, I've gone on a bit!) do I need to include the earths to the shaver socket and shower in the equipotential bonding? If so, physically how do I loop them into this unbroken length of 4mm cable? Even if I break into the cable, I just don't think there would be enough space in the screw terminals to take the cable already supplying the shower/shaver AND two more 4mm cables/one doubled over cable.
I live in a block of flats and none of my pipework etc is cross bonded. I assume (?) that the main gas and water pipes supplying all of the flats are earthed where they enter the building (about 80 feet from my flat). Do I need to attach earth clamps to them where they enter my flat and link them back to the CU?
Which brings me to my next point - linking anything back to the CU is hard work (at least trying to do it neatly) because the floors are concrete and all cabling is run in the half inch space above the plasterboard ceiling. I have managed to lead a 10mm earth wire from the CU across into the void space where all of the service ducting, pipework etc is located. I put a 4-way earthing connector block on the end of this 10mm cable and used it to supply an earth to the new light fitting I put up in the bathroom. (I know the lighting circuit should have an earth but the cabling seems to be in good condition [it is 1960s] and given the problem feeding cables a total rewire of the lighting circuit would be a pretty big job). Can all of my bathroom and kitchen cross bonding be linked back to this 4-way connector block, and thus back to the CU through the one 10mm cable?
In the kitchen I was planning to cross bond the sink, cold and hot pipes (what about the gas pipe?) and link them back to the earth block in the void. Does it matter where I attach the earth clamps to the pipes, ie under the kitchen sink or about 2 feet from the sink on the other side of the wall in the void space? This is pretty much the point at which the cold and gas pipes enter the flat.
In the bathroom, I was planning to connect together all cold and hot pipes supplying toilet, sink, bath, shower, and earth the bath itself and then connect these back to the 4-way earth block. All of these pipes to toilet sink etc come through the wall from the void - can I put the earth clamps on the pipes on the void side of the wall (neater looking job), or do they all have to be on the bathroom side of the wall (there would only be about 6 inches difference).
[Incidently, looking at pictures of equipotential bonding in bathrooms in books, although the toilet, sink and bath are all fed off one cold water pipe via T pieces, the piece of pipework leading to each of them has its own earth connection - why can't you just earth the pipe once? Is it because you can't assume that the solder/compression fittings used to T off the main pipe will provide a low resistance path? ]
Am I ok using 4mm for all of this (I have seen some say 6mm)? Does it definitely have to be an unbroken length of cable with the earth clamps threaded on where in the insulation is stripped off?
Lastly (sorry, I've gone on a bit!) do I need to include the earths to the shaver socket and shower in the equipotential bonding? If so, physically how do I loop them into this unbroken length of 4mm cable? Even if I break into the cable, I just don't think there would be enough space in the screw terminals to take the cable already supplying the shower/shaver AND two more 4mm cables/one doubled over cable.