Mobile home earthing/bonding?

Yes each unit should have its own rod. No point in anything bigger than a 6mm2 earth or bond, its not the same as TN systems. Look at section 708 in the regs.

 

What sort of site are we talking about? A holiday type caravan park or a mobile home park site?

Section 708 applies to Liesure accommodation vehicles (static or not). It doesn't apply to residential/transportable/mobile units.

16amp supplies suggests it's for holiday use.

Assuming so, section 708 would apply to the supplies to the vans, and the sub distribution up to them.

A TT supply is fine. A TN-S would also be fine, but a TN-C-S is not permitted, and is actually prohibited under the ESCQR regs.

As with any TT, the upfront RCD should be time delayed, and 100mA or higher. You don't need to rod down each van, but the more rods the better. The sub circuits to the vans must be protected by a 30mA RCD, although in true cross over fashion, static and touring holiday accommodation vehicles also require a 30mA RCD at their origin too.

 

Its difficult knowing where these types of van sit in terms of section 7. They are not a caravan or motor caravan, and neither are they a transportable unit. They do share some of the distinguishments though. They are classed as Liesure Accomodation Vehicles.

If you look at them, they deviate from section 721 in several ways, even brand new ones. That's because they are not classed as caravans, so this section doesn't really apply.

They are awkward in terms of the regs.

Gas bottles are usually connected with a final tail of hose. The NIC say even in homes, this is clearly not extraneous, and while they would prefer to see it bonded, they don't insist it's done.

 

If it's static, then treat it as any other standard installation.
If not static, then Section 7 applies.

 

Be careful I made a huge mistake with a semi-permanent caravan site. I was sent to fit earths still in the days of 16th Edition BS 7671:1992 and I just went about fitting them all without any real thought as to what it could mean. No access to most of the caravans the guys were at work so just a cable connected to chassis.

However that evening my boss visited the caravan site to find most were on ELCB-v the old yellow button type and my work had rendered them all useless.

Also it would seem if the caravan is deemed a home rather than a tow-able caravan there are minimum requirement that class it as inhabitable I could never find the regulation but was informed they must have at least a 32A supply. The guy telling me was rather upset as he had some units on his site and to give them a 32A supply was a real headache fortunately he only at that time had two I assume it was the local council who had told him and it resulted in him reducing the number of units by 6 just so he could give these two the supply required.

As soon as one starts up grading it seems everyone wants their slice of the cake. And what was going to be a gradual event turns into a rush to supply. Trying to use some reason and explain if you really want that lot I will just have to close the site never seems to work.

The only way seems to be to plan for whole upgrade and split it into phases. Twin and earth has been used outdoors for years but it's not designed for outdoors and is only supplied for domestic use so using it even in plastic water pipes leaves one wide open should anyone do something daft. Once you start you are going to have to issue installation or minor works and put your name on the paperwork. 9 times out of 10 nothing goes wrong but when it does you get Emma Shaw size problem for any electrician involved.

I does not matter is the work is spread out over 5 years but if you try to do it on the cheap people don't say we he was only trying to help they want to point fingers.

For the guy with a shed maybe we can take a chance but on a commercial site not really worth the risk.