On a kitchen refubishment my contractor has charged for earth bonding and charged again for earth bonding to gas and water main is this correct?

Under the 17th edition regulations BS7671:2008 as ammended to 2011, provided all electrical circuits are RCD protected there is no need for supplementary earth bonding to the kitchen sink or within the bathroom. It sounds like your builder is qouting based on his knowledge of the old 15th edition regulations and is either not a part P NICEIC registered electrician or needs to go on an update course! Whilst there is nothing wrong with the extra bonding from an electrical viewpoint, it may not actually be required and hence you may have paid for something you don't really need. My advise is never use builders to do electrical work! They often overcharge and seldom know the latest electrical regulations. I bet he has not given you an electrical certificate for the work either? Main bonding to gas an water in 10mm cable should be no more than £60 max.

supplementary bonding is only required if the earth loop impedance exceed (the zs) of a 30ma rcd which is 1667ohms or all circuits are not protected by a 30ma RCD.

I'm not an electrical expert as I use a qualified electrician for all my kitchen and bathroom installations. However I did have a similar conversation with him the other day. All my kitchen electrical installations are now installed to the 17th edition regulations which means that all the circuits in the kitchen are RCD protected. This means that there is no longer a requirement for supplementary bonding but the water main and gas feed do still require a 10mm bond. This raises a couple of questions beyond the original one for the original poster. Has the kitchen wiring been protected using RCD's as it should be under current regulations unless there has been no modifications to the kitchen wiring which is unlikely. I know that there always seems to be a certain amount of room for interpretation under any edition of the regulations and electricians can advise certain things be done in a similar way that some items that don't cause a car to fail an MOT are still listed as an advice note to have remedied. As I say I'm not an electrician so please consult one rather than take my advice. All I can say is that all my kitchens are upgraded to RCD protection as I consider it to be the best solution and I have peace of mind that my customers's are as safe as they can be.

hi, by the sounds of what you are explaining it sounds to me that the contractor is saying that he/she has allowed for supplementary bonding to the kitchen, which basically means that items such as local copper pipework are cross bonded which is a requirement under regulations,and within the bathroom all pipework and each seperate electrical item are interlinked with a earth bond which should really be a minimum of 4mm. The main bond to gas and water are now required to be of a minimum cross section of 10mm. Each item that has a bond requires an earth clamp for the cables to be terminated.Hope this clears the matter up for you

Your contractor sounds decent as at least he is quoting for upgrading the earthing and not omitting this work entirely. The first answer you received on here is the perfect answer to your question. Always get ensure a Part P registered electrician undertakes your electrical work. Good luck

your contractor is correct