No of a a one system which is using the steel strands as an earth. They have someone going and putting rods in but the main supply cable to the box with cartiridge fuses is the issues to this needs a large separate earth or one big old rod. Plus all the strands will then need to be disconnected. Or install an mccb with rcd attatment but they won't listen. I'm just nervous about doing anything there now tbh
Of the box is not metal with no extrenous parts inside then it probably will not require an earth rod. The caravans however must have earth rods.
The boxes are plastic the earth rods are to try and get the impedance value down. There are 4 or 5 points on a radial so i assume what there doing is putting in earth rods connected in series hopefully reducingbthe impedance value. You say each caravan should have an earth did but there a static unit. Come pre_wired with a 16A flex with an earth. If you installed a rod then it's pointless having a 3 core flex. But from ensuring the safety if the occupants that mint be a good way to go. Units all rest good and are safe then supply is there issue.
You must not export an earth from a PME supply to a caravan. Static or not (all caravans will be static when plugged in). All the caravans must be connected via an earth rod with ideally a sub-200 ohm reading. You need to read section 7 of BS7671. There is a complete section dedicated to caravans.
So get rid of the earth going to the commando point and install a spoke. Sounds fine but trying telling them that unless ibfail then on that point. Cheers for the advise tho. I'll do some new time reading.
Your job as tester is to just tell them the state of their installation. Not to worry about whether they listen to your report or not. Don't take it personally. But if you are testing a caravan site it is essential you read up on the regs.
I am but the I have to do an impedance test and note the high values. Because the units are connected to this sorry syate of an install the report becomes unsatisfactory due to high impedance values. I thought I would be sorting it out but they don't want that. But if I tell them that for a pass they need these earth rods then atleast the caravans are safe. The supply is then there issue when it all goes to pot.
Are these leisure accomodation or residential? There are certs from the NIC you can use for leisure accomodation type mobile homes, and they concentrate purely on the vehicle, not the supply. While the supply is an issue, that's the "parks" issue. Sure, note it, but it's not a direct requirement on the NIC certs. Mobile home parks and caravan sites often have the worst and scary infrastructure you can come across, usually done on the cheap by themselves and friends. I maintain several sites, and luckily they are built and maintained to a high standard. I hate turning up to bodged and dodgy sites.
Residential. I thought the NIC would have a separate sheet for them but haven't found them on there site yet I'll have a look. The worse part is they have too units and want to double them. Plus renovating barns into flats and a swimming pool. They have run a 6mm arnoured cable about 1000m with a couple of 1.5 armoured coming off it to supply street lights. He seemed proud when he said the park had done that bit
I have read that a caravan site can only be a tn-s or a tt sytem. Or if it's pme supplying pitches needs to be disconnected at the panel and made into a tt
If they're not leisure accomodation, you can't use the NIC (paid for) certs. On caravan sites, you can only use TN-S or TT, as with PME, if the neutral is lost, the earth becomes live via your load. Effectively, any caravan chassis can then become live. Imagine trying to unlock the aluminium door.... Mobile home residential sites get tricky. Some new homes turn up with a meter box fitted flush in them, and the DNO happily go and install a cutout, and the meter operator a meter. Have a good read of the definitions section of the regs and section 7.
You can divorce the PME earthing, and turn to TT for the van, this is fine and accepted. However, the SWA feeding the point of divorce still needs protection. If the SWA is rotting and giving shlte results, it is not protected against faults.
To my mind the report relates to the caravan. The origin of the installation is the hook up point. The supply to the hook up points, is a private distribution network. As such the supply to the hook up point is not the OP's concern other than to make a comment.
From the original post I tend to agree, but it all depends on the scope defined in the agreement between the owner and Benjy. If the scope was test the caravans then he has done his job and it is down to the owner. Kind regards
If his scope is to test the caravan then it should be just dead tests only. It is down to the caravan park to ensure they provide the 'tenants' with a satisfactory electricity supply.
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