Sling92 Posted January 16, 2005 Share Posted January 16, 2005 Hi All Couple of questions for the electricians amongst you: 1 Earth Spike We are currently having a new concrete floor installed into our renovation. As long as the cable to the fusebox is protected can I bury the earths pike within the floor, never to be seen again, or does it need to be available for inspection? I think it might have to be outside, but I'm not sure.2 Sub mains As our house is very long (30m) and, typically, the EDF install is at the other end to the proposed kitchen I was going to run a set of 10mm cables from the main trip to a 'sub board' within the kitchen, which would feed dishwasher, oven, boiler etc. Is this permissable or not? Does it need to go throught the main fuse board (and be protecetd with a 40A trip or something) or is it OK stright off the trip as long as the cable size is the same as the main board? Hope you can help Cheers Simon and Liz (87) Link to comment Share on other sites More sharing options...
Nick Trollope Posted January 16, 2005 Share Posted January 16, 2005 [quote]Hi All Couple of questions for the electricians amongst you: 1 Earth Spike We are currently having a new concrete floor installed into our renovation. As long as the cable to the fusebox is prot...[/quote]HiI believe that the earth spike must be a) outside & b) accessible and c) suitable - you can't always get the required resisitance with 1 spike (around here at least). You can run your 10mm cables to a second tableau, and provided it has it's own ID or DD, can be from the "input" side of the existing tableau. This is basically what we do (for much the same reason, plus some accessibility issues) & Paul (punch) our resident expert told me it was OK. So now he will tell me that I am talking bollocks. Which I usually do. Link to comment Share on other sites More sharing options...
Ianhaycox Posted January 16, 2005 Share Posted January 16, 2005 I believe the maximum length for a 10mm cable at 45A is 22 meters so you might consider using a 16mm cable (good for 36 meters).For three phase double the above max lengths. Link to comment Share on other sites More sharing options...
Gyn_Paul Posted January 16, 2005 Share Posted January 16, 2005 [quote]Hi I believe that the earth spike must be a) outside & b) accessible and c) suitable - you can't always get the required resisitance with 1 spike (around here at least). You can run your 10mm c...[/quote]"..........I believe that the earth spike must be a) outside & b) accessible and c) suitable - you can't always get the required resisitance with 1 spike (around here at least)......" Nick, Is this 'outside' bit new? I buried the spike in the concrete (well, in the ground before the concrete was poured) just below where the tableau is sited in the laundry. Just the top of it is showing then it is connected to a borne (2 porcelain isolators with a copper bar across them to measure the earth resistance) then it switches from unsheathed copper to the usual insulated stuff and goes into the wall and into the back of the tableau.Consuel didn't have a problem with it in 1998. (or maybe he just didn't notice? )paul Link to comment Share on other sites More sharing options...
Nick Trollope Posted January 17, 2005 Share Posted January 17, 2005 [quote]"..........I believe that the earth spike must be a) outside & b) accessible and c) suitable - you can't always get the required resisitance with 1 spike (around here at least)......" Nick, ...[/quote]PaulI don't know, I'm afraid. I was hoping that t'other Paul would put me right. My info could be a long time out of date... Link to comment Share on other sites More sharing options...
Punch Posted January 17, 2005 Share Posted January 17, 2005 Just noticed this post, funny 'cos I'm off to replace an ineffective earth spike for someone in my village this morning who is due a Consuel visit.The earth spike is often buried and inaccesible, but the regs say it should be accessible and preferably within it's own "regard". I always therefore do this, as it does depend on the inspector from the Consuel, who could in theory ask to see the connection to the spike. On the whole though and in my experience, he would just take a measurement (which must be below 100 ohms).Nick -, the earth spike doesn't have to be outside, in fact the one I wil do this morning is in a cellar, but you right to mention it should be accesible.Ian is correct in mentioning the voltage drop and maximum length of run for 10mm cables is 23 metres. I agree 16mm is required and this will give flexibility if you upgrade to 60 a -12KW as the maximum length is 27 metres in 16mm monophase.Paul Link to comment Share on other sites More sharing options...
Sling92 Posted January 17, 2005 Author Share Posted January 17, 2005 Thanks for your helpful responses fellasOff to buy some gaine big enough for 16mm! Thanks a lot Simon Link to comment Share on other sites More sharing options...
Guest CFrost Posted January 18, 2005 Share Posted January 18, 2005 Just for info, the reason given for keeping the connection to an earth spike visible and clear of soil is to meet the requirement of preventing any corrosion due to the chemical action of dissimilar metals (copper wire & steel earth spike). It seems OK to completely bury copper earth mats and connectors. Link to comment Share on other sites More sharing options...
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