Dave Jones Posted November 21, 2020 Share Posted November 21, 2020 you need an earth spike in the ground for the temp supply or they wont connect it. Western power rule. Link to comment Share on other sites More sharing options...
PeterW Posted November 21, 2020 Share Posted November 21, 2020 27 minutes ago, mattp22 said: Hi, about 20 metres 20-22m at 100A needs a 25mm Armoured cable buried in the ground. Link to comment Share on other sites More sharing options...
PeterW Posted November 21, 2020 Share Posted November 21, 2020 2 minutes ago, Dave Jones said: you need an earth spike in the ground for the temp supply or they wont connect it. Western power rule. This isn’t a temporary supply. It’s what a lot of people have done, put the permanent meter in a meter box at the boundary and then use that to supply the build site and you don’t need to move the meter when the house is built. It then doesn’t need an earth spike as it uses the supply head earth, although if it is used to supply to a static caravan then you may need a second earth but @ProDave can advise on that one ! Link to comment Share on other sites More sharing options...
Dave Jones Posted November 21, 2020 Share Posted November 21, 2020 1 minute ago, PeterW said: This isn’t a temporary supply. It’s what a lot of people have done, put the permanent meter in a meter box at the boundary and then use that to supply the build site and you don’t need to move the meter when the house is built. It then doesn’t need an earth spike as it uses the supply head earth, although if it is used to supply to a static caravan then you may need a second earth but @ProDave can advise on that one ! so how you get the mains supply cable out of the hockey stick so you can put the recessed meter box in and then re-thread the cable through the stick and into the box? Link to comment Share on other sites More sharing options...
ProDave Posted November 21, 2020 Share Posted November 21, 2020 4 minutes ago, PeterW said: This isn’t a temporary supply. It’s what a lot of people have done, put the permanent meter in a meter box at the boundary and then use that to supply the build site and you don’t need to move the meter when the house is built. It then doesn’t need an earth spike as it uses the supply head earth, although if it is used to supply to a static caravan then you may need a second earth but @ProDave can advise on that one ! Yes any "building" with a metal outer skin, where the earth would normally be bonded to that skin, is prohibited from being connected to a PME earth. So your static caravan, metal shed, and your general purpose site power socket, you do not connect to the suppliers earth, but instead provide your own local TT earth (earth rod) for those. For a 20 metre run from meter box to house and an 80A fuse in your switch fuse, you can get by with 16mm SWA, though 25mm would be better. 1 Link to comment Share on other sites More sharing options...
ProDave Posted November 21, 2020 Share Posted November 21, 2020 5 minutes ago, Dave Jones said: so how you get the mains supply cable out of the hockey stick so you can put the recessed meter box in and then re-thread the cable through the stick and into the box? YOU don't. The point of this arrangement is for those that want to get the supply put in once and once only. So you get the supply connected into a meter box that is fixed in some way to something permanent. Then when the house is built, you keep the meter in the same place an run a cable to the house. If you want your supply head and meter in a recessed meter box on the wall of your new house, then you have to pay the supplier for a temporary site supply, and then pay them again to move the supply into the house meter box when you are ready. That is made more complicated now by requiring the DNO and your supplier to both visit on the same day, the DNO comes first to move the supply, then later in the day your supplier comes to move the meter. Link to comment Share on other sites More sharing options...
PeterW Posted November 21, 2020 Share Posted November 21, 2020 25 minutes ago, Dave Jones said: so how you get the mains supply cable out of the hockey stick so you can put the recessed meter box in and then re-thread the cable through the stick and into the box? You don’t ..? You use a surface box or a recessed box in a boundary wall or a GRP enclosure and then you run your house supply from the isolator in the meter box. Link to comment Share on other sites More sharing options...
mattp22 Posted November 21, 2020 Share Posted November 21, 2020 22 minutes ago, PeterW said: 20-22m at 100A needs a 25mm Armoured cable buried in the ground. Thanks for clarifying, much appreciated Link to comment Share on other sites More sharing options...
ProDave Posted November 21, 2020 Share Posted November 21, 2020 23 minutes ago, PeterW said: 20-22m at 100A needs a 25mm Armoured cable buried in the ground. You really want to use an 80A fuse in your switch fuse to discriminate from the suppliers 100A fuse, and that would allow you on up to about 24 metres to use 16mm if you really wanted to. 1 Link to comment Share on other sites More sharing options...
Dave Jones Posted November 21, 2020 Share Posted November 21, 2020 ah the non temporary bodge method of leaving a white box on a post. no thanks. Link to comment Share on other sites More sharing options...
PeterW Posted November 21, 2020 Share Posted November 21, 2020 5 minutes ago, Dave Jones said: ah the non temporary bodge method of leaving a white box on a post. no thanks. Not at all - there are plenty of ways of doing it. These were installed in the back of a boundary wall - all permanent and signed off by WP and electrician. Link to comment Share on other sites More sharing options...
Dave Jones Posted November 21, 2020 Share Posted November 21, 2020 and still looks crap. Link to comment Share on other sites More sharing options...
Russell griffiths Posted November 21, 2020 Share Posted November 21, 2020 (edited) I’m unsure why nobody does what we had in Australia. You mark out the house footprint and get the recessed box installed in the correct location but fixed in place on two posts, dno installed the meter, as the brickies bring up the brickwork they remove the wooden posts and build the box in, there is enough movement in the cable to wiggle the box to get it to line up with the brickwork. ?♂️?♂️?♂️?♂️ Edited November 21, 2020 by Russell griffiths Link to comment Share on other sites More sharing options...
PeterW Posted November 21, 2020 Share Posted November 21, 2020 2 minutes ago, Dave Jones said: and still looks crap. ..?? Looks like a standard in wall meter box to me. One to the right has a small CU and automation for gates / lights Link to comment Share on other sites More sharing options...
ProDave Posted November 21, 2020 Share Posted November 21, 2020 33 minutes ago, Russell griffiths said: I’m unsure why nobody does what we had in Australia. You mark out the house footprint and get the recessed box installed in the correct location but fixed in place on two posts, dno installed the meter, as the brickies bring up the brickwork they remove the wooden posts and build the box in, there is enough movement in the cable to wiggle the box to get it to line up with the brickwork. ?♂️?♂️?♂️?♂️ It would be interesting to see the inside of one of these meter boxes. I wonder what sort of cable clamp they use? The UK standard supply head has no cable clamp, the cable ends just terminate into the supply head and are fine because nothing moves, but if you are moving a live meter box there is a risk of a connection coming loose which would probably end badly. Link to comment Share on other sites More sharing options...
Russell griffiths Posted November 21, 2020 Share Posted November 21, 2020 1 hour ago, ProDave said: It would be interesting to see the inside of one of these meter boxes. I wonder what sort of cable clamp they use? The UK standard supply head has no cable clamp, the cable ends just terminate into the supply head and are fine because nothing moves, but if you are moving a live meter box there is a risk of a connection coming loose which would probably end badly. They are built in flush face type boxes look like ours, but metal with a metal door with a couple of rows of louvers. Seems like an easily achievable solution. Link to comment Share on other sites More sharing options...
Randomusername Posted December 19, 2020 Share Posted December 19, 2020 On 21/11/2020 at 17:02, Dave Jones said: you need an earth spike in the ground for the temp supply or they wont connect it. Western power rule. Western Power Distribution here in Lincolnshire have confirmed to me that they have no interest in finding an earth spike in-situ when they come to run the supply from the pole to my TBS supply. Until something is supplied from the box, ie there is a meter and main switch/consumer unit in place, it’s not classified as a usable supply and does not require a TT at the point of connection. However by the time that the meter installer arrives, they would expect to see the earthing rod in place as the supply is then classified as live and usable on completion. Link to comment Share on other sites More sharing options...
ProDave Posted December 19, 2020 Share Posted December 19, 2020 Nobody checked my earthing. Sometimes the DNO do not provide an earth terminal with a TBS forcing you to install your own. Link to comment Share on other sites More sharing options...
Onoff Posted December 19, 2020 Share Posted December 19, 2020 The DNO made me PME without me even knowing. Always happy with a rod the house-sitter called them when a tree came down on the overhead. Arrived back from holiday to find a new connection from the pole and a PME sticker on the head. Link to comment Share on other sites More sharing options...
Randomusername Posted December 20, 2020 Share Posted December 20, 2020 18 hours ago, ProDave said: Nobody checked my earthing. Sometimes the DNO do not provide an earth terminal with a TBS forcing you to install your own. I’m assuming that as they’re going to be providing power from a PME feed but insisting that I TT on site, they will not provide a MET and I’ll have to fit one in the cabinet attached to my earth rod, and completely separate from their cabling? However that doesn’t change the fact that their supply neutral will still be tied to their PME earth as there is no way of keeping them separate when they’re visibly connected on the casing of the local transformer! ? Link to comment Share on other sites More sharing options...
ProDave Posted December 20, 2020 Share Posted December 20, 2020 44 minutes ago, Randomusername said: I’m assuming that as they’re going to be providing power from a PME feed but insisting that I TT on site, they will not provide a MET and I’ll have to fit one in the cabinet attached to my earth rod, and completely separate from their cabling? However that doesn’t change the fact that their supply neutral will still be tied to their PME earth as there is no way of keeping them separate when they’re visibly connected on the casing of the local transformer! ? The point is, with PME delivered by a concentric cable with a combined N and Earth conductor, in the event of the PEN failing (not unknown) the N AND E potential can rise to close to L potential. That is VERY bad news for someone trying to enter a metal static caravan that has it's chassis bonded to E. While standing on the ground (true earth) he could touch a metal door that is at 240V. Same for an earthed power tool being used on site. Yhis is why the site power sockets and static caravans etc should be TT earthed. I still have the PME earth next to my supply head which is used to feed the house. The static caravan is not earthed to this, rather it is earthed to a rod banged into the ground just next to the 'van. It's just that some DNO's if they think this is a site supply do not give you any earth terminal at the supply head to force you to provide your own earth, Link to comment Share on other sites More sharing options...
Randomusername Posted December 20, 2020 Share Posted December 20, 2020 I understand the why - and in just about any situation a static caravan or even a metal shed should be TT earthed as near as possible to it, even if it’s being fed by a PME supply inside a nearby building. I just don’t get what circumstance might arise which could lead to the loss of the neutral/earth conductor in concentric cable, where the phase conductor is not also severed or shorted out sufficient to blow the main supply fuse at pole or substation... Link to comment Share on other sites More sharing options...
ProDave Posted December 20, 2020 Share Posted December 20, 2020 43 minutes ago, Randomusername said: I just don’t get what circumstance might arise which could lead to the loss of the neutral/earth conductor in concentric cable, where the phase conductor is not also severed or shorted out sufficient to blow the main supply fuse at pole or substation... The commonly used concentric cable, damage to outer sheath or poor (non waterproof) underground junction. Water gets in, outer conductor corrodes and fails. For the inner to fail, the insulation to that would also have to fail but since it's inside it's unlikely to get damaged so much less likely. I have seen it in a house, the DNO had to dig up a lot of his driveway before they found the fault. Many argue the concentric cable is a poor design. Link to comment Share on other sites More sharing options...
TonyT Posted December 20, 2020 Share Posted December 20, 2020 Best to keep that rod handy, maybe needed for the EV charging point or the hot tub to stop you exporting PME Link to comment Share on other sites More sharing options...
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