Earthing Supply Static Caravan

mjtefc9 · Tuesday at 10:57 AM

Hi All,

My static caravan has a ZS of 1.13.. which is very low ! I was expecting a TT.. I have not tested myself as this was on the cert I have just got after waiting for it. I'm going up next week with my Fluke, I doubt they will give me access to the incoming building, how can I be sure its TT from the caravan itself?

TIA

richy3333 · Tuesday at 12:43 PM

Test at the hook up point with a commando socket or at the caravan DB?

littlespark · Tuesday at 12:45 PM

Is your caravan on an actual caravan site? There is a whole section in the regs for sites.

The Zs does have to be as low as possible, and 1.13 isn’t what I would say was particularly high

mjtefc9 · Tuesday at 12:55 PM

richy3333 said:
Test at the hook up point with a commando socket or at the caravan DB?

I was going to plug in and do a ZS L-PE and then L-N.. see what it says?

mjtefc9 · Tuesday at 12:57 PM

littlespark said:
Is your caravan on an actual caravan site? There is a whole section in the regs for sites.

The Zs does have to be as low as possible, and 1.13 isn’t what I would say was particularly high

Yes, all setup and on site

I know, but its really low considering it should be TT.. The kids want the lazy spa put in and I'm just not sure..

littlespark · Tuesday at 1:32 PM

Check your site license about hot tubs and the like.

Not all sites are capable of extra electric load, such as hot tubs, ev chargers etc…. And the water supplies could be the same.

The site will have to pay for water through a meter, they may not be very understanding if you’re filling a tub

mjtefc9 · Tuesday at 1:34 PM

littlespark said:
Check your site license about hot tubs and the like.

Not all sites are capable of extra electric load, such as hot tubs, ev chargers etc…. And the water supplies could be the same.

The site will have to pay for water through a meter, they may not be very understanding if you’re filling a tub

TBF they have asked me to fit a few sockets in the park, I'm just wary due to the lack of earthing info.

littlespark · Tuesday at 1:40 PM

Sorry, I’m coming from being an electrician who has also been a caravan site manager at one time, and we had people attempt all sorts of dodgy things in their statics.

Customer: my son tried to fit a shower in my caravan but it keeps tripping.

Me: it’s a 8.5kW shower…. What did you think would happen on a 16A supply?

mjtefc9 · Tuesday at 1:45 PM

littlespark said:
Sorry, I’m coming from being an electrician who has also been a caravan site manager at one time, and we had people attempt all sorts of dodgy things in their statics.

Customer: my son tried to fit a shower in my caravan but it keeps tripping.

Me: it’s a 8.5kW shower…. What did you think would happen on a 16A supply?

Don't apologise! I need advice! Thank you so much.. once I know the earthing and I'm happy I'll explain the likelihood of it tripping ! TBH I'm in two minds about bringing mine to the site as it tripped the other day charging the car anyway..

What would you do ? The site has just given me a rubbish generic test sheet with no supply info on.

mjtefc9 · Tuesday at 4:14 PM

Just had a reply from the park manager.. no earth rods.. it comes in overhead !?!

richy3333 · Tuesday at 4:33 PM

eh? Surely comes in as a TN system and then is made into TT for the vans?

mjtefc9 · Tuesday at 5:53 PM

richy3333 said:
eh? Surely comes in as a TN system and then is made into TT for the vans?

You would think, they don’t seem to think it’s an issue as they all have RCD protection!?!

littlespark · Tuesday at 7:49 PM

I’ve got me regs book here…

“708.411.4 TN system
The …. (ESQCR) prohibit the connection of a PME earthing facility to any metalwork in a leisure accommodation vehicle”

And

“708.415.1 RCDS)
Every socket outlet shall be individually protected by an RCD having a rated residual operating current not exceeding 30 mA”

So that’s yes to RCD protection, and an earth system other than PME….. so that suggests TT off earth rods

mjtefc9 · Wednesday at 2:17 PM

littlespark said:
I’ve got me regs book here…

“708.411.4 TN system
The …. (ESQCR) prohibit the connection of a PME earthing facility to any metalwork in a leisure accommodation vehicle”

And

“708.415.1 RCDS)
Every socket outlet shall be individually protected by an RCD having a rated residual operating current not exceeding 30 mA”

So that’s yes to RCD protection, and an earth system other than PME….. so that suggests TT off earth rods

Do you think it could be a TN-S supply? This place has parks all over, surely they wouldn’t choose to break the law on something that’s easily rectified?

diditrain · 2025-06-05T08:18:13+0100

mjtefc9 said:
Do you think it could be a TN-S supply? This place has parks all over, surely they wouldn’t choose to break the law on something that’s easily rectified?

Is this a caravan or a statics home?

mjtefc9 · 2025-06-05T08:25:15+0100

diditrain said:
Is this a caravan or a statics home?

Static caravan holiday park

littlespark · 2025-06-05T10:33:13+0100

I’m going to be pedantic for a change.

There’s actually no such thing as a “static caravan”
Those big beige or green sheds are either “holiday homes” or “(residential) park homes”

And there’s a build difference between the two,
But the electrical supply regs are the same.