Supply to static permanent residence caravan

[Daxydoggie]

Hi, looking for some advice for supply to static permanent caravan at bottom of garden.
My House supply is TT. From what I can gather from previous thread s, is this acceptable.
House end, SWA terminated into plastic ad.box and l+n tails into non RCD side of cu, from suitably rated MCB. Armour not connected, neither is SWA earth (it's a 3c 6 xlpe).
Caravan end. SWA terminated into box and tails into standard existing cu, which is RCD protected for caravan ring and lights. Earthing to separate rod beside van, and everything cross bonded at this end to give a local TT.

Do I bond armour at all, if so which end(s)?
Does the 3rd core in SWA effectively become redundant, as don't want to export/extend earth between house and van as 30m and also soil conditions very different.

I've attached pics of both ends.

Thank you.
Craig.

View attachment 35536

View attachment 35537

 

[westward10]

Don't see why you need a rod at the caravan use the house one. When you say non rcd side I see what you mean but what is the separate rcd, is that the main switch and if so is it greater than 30ma.

 

[Richard Burns]

As it is a TT supply (presumably the main switch on the right is a time delay 100mA RCD) then there would be no problem in combining the earthing systems between the two locations.
It is absolutely critical for safety that the armour of the SWA is earthed.
If you go with the two separate TT systems then the armour should be earthed at the supplying end and kept isolated at the far end. If the two are not separate then earthing at both ends is best.
The same with the earth core of the SWA.

 

[Daxydoggie]

As it is a TT supply (presumably the main switch on the right is a time delay 100mA RCD) then there would be no problem in combining the earthing systems between the two locations.
It is absolutely critical for safety that the armour of the SWA is earthed.
If you go with the two separate TT systems then the armour should be earthed at the supplying end and kept isolated at the far end. If the two are not separate then earthing at both ends is best.
The same with the earth core of the SWA.

The rhs is a wylex 100ma current operated elcb ref: Wem 80/2.
I thought the setup has to be separate TT, didn't know that its permissible to extent the house TT via armour and core to static caravan without separate rod.

 

[westward10]

Not time delayed the rcd not ideal but doesn't matter. It is perfectly acceptable to use the existing TT system. I would earth the armour at both ends but use the separate core as the cpc. How far from the house is the caravan, you could employ another rod at the caravan to equalise any potential difference but personally I wouldn't bother.

 

[Daxydoggie]

Not time delayed the rcd not ideal but doesn't matter. It is perfectly acceptable to use the existing TT system. I would earth the armour at both ends but use the separate core as the cpc. How far from the house is the caravan, you could employ another rod at the caravan to equalise any potential difference but personally I wouldn't bother.

Crow flies 30m, cable length however, bout 45 between the two units.

So, just to confirm, OK to supply from suitably rated MCB on the non rcd side of the split load house cu, as the unit in the caravan is rcd protected anyway.

Thanks so far!

 

[westward10]

What size breaker are you putting it on.

 

[Daxydoggie]

What size breaker are you putting it on.

I think 32a on the supply end.

 

[telectrix]

holdon. if the house is TT and the static presumably TT as well, thar SWA needs RCD protection at the house end to provide fault protection.

 

[Daxydoggie]

holdon. if the house is TT and the static presumably TT as well, thar SWA needs RCD protection at the house end to provide fault protection.

This was the whole point of the post really, trying to explore the good/bad of exporting tt earth to van etc, as lots of different opinions on this, now that I know from it is permissable to forget the separate earth arrangement at the van and connect the two, I should come off the rcd protected side of the house cu? The house board is elcb and all the caravan cu is rcd on the feed?

 

[westward10]

holdon. if the house is TT and the static presumably TT as well, thar SWA needs RCD protection at the house end to provide fault protection.

It will have from the separate 100ma main switch.

 

[Daxydoggie]

It will have from the separate 100ma main switch.

Ok then, just to be sure, should I rejig the house split load cu and come off an RCD protected circuit with a 32mcb, as the wylex elcb(it is current but not timed)is a bit of a dinosaur then? See photo.

 

[westward10]

Ok then, just to be sure, should I rejig the house split load cu and come off an RCD protected circuit with a 32mcb, as the wylex elcb(it is current but not timed)is a bit of a dinosaur then? See photo.

No but I would recommend you have the 100ma rcd tested to confirm its operation in fact those old Wylex rcds remain reliable regardless of age.

 

[Daxydoggie]

No but I would recommend you have the 100ma rcd tested to confirm its operation in fact those old Wylex rcds remain reliable regardless of age.

Thanks for all your time.
If it were you would you seperate the earths or combine, reason I ask is ive seen so much contradiction esp on the iet site! Just wanted your take!

Also the water to caravan is mdpe platic but after stop cock it's all copper, and the van skin and chassis is metal. This should all be bonded and back to earth at van cu regardless of which of the 2 options discussed previously?

Many thanks.

 

[westward10]

Thanks for all your time.
If it were you would you seperate the earths or combine, reason I ask is ive seen so much contradiction esp on the iet site! Just wanted your take!

Also the water to caravan is mdpe platic but after stop cock it's all copper, and the van skin and chassis is metal. This should all be bonded and back to earth at van cu regardless of which of the 2 options discussed previously?

Many thanks.

The water service being supplied in plastic is highly unlikely to be extraneous and wouldn't need a bond, the internal copper work would essentially be "floating" and could have supplementary bonding. The Regulations in my opinion are somewhat out of touch with current service supplies assuming they are metal piped and in contact with terra firma which makes them extraneous not taking into consideration insulated services. Exposed metalwork of the caravan would need testing to ascertain whether it is extraneous. Personally I would bond it, this bond would have to be sized in relation to the earthing conductor at the origin electrode but then this may be complicated by the 6.0 limitation of the supply cable cpc. As this is a TT system I don't think this would be a huge issue.

 

[Midwest]

Re the 'van skin and chassis is metal' thing, just looked at IET Wiring Matters article on the subject, which highlighted the following reg;

Regulation 721.411.3.1.2, Structural metallic parts that are accessible from within the caravan shall be connected through main protective bonding conductors to the main earthing terminal within the caravan.

 

[Daxydoggie]

Re the 'van skin and chassis is metal' thing, just looked at IET Wiring Matters article on the subject, which highlighted the following reg;

Regulation 721.411.3.1.2, Structural metallic parts that are accessible from within the caravan shall be connected through main protective bonding conductors to the main earthing terminal within the caravan.

Thanks Midwest, yeah will bond lpg gas pipe + copper water pipes + van outside skin + probably metal chassis underneath which probably couldn't be touched inside but may as well. Good job it's a wooden floor and walls! Ta.

 

[Daxydoggie]

No but I would recommend you have the 100ma rcd tested to confirm its operation in fact those old Wylex rcds remain reliable regardless of age.

Columbo here, one last thing.....
As you'll see in the pick there is a spare non rcd protected way (but protected by main wylex ) on the right just before rccb, was going to bang the caravan feed into a 32mcb type b there, would that be acceptable, or should they (non RCD mcbs) be reordered in load order, highest at lhs?

 

[westward10]

No that is an old wives tale, makes no difference.

 

[Daxydoggie]

No that is an old wives tale, makes no difference.

Ive got a thing for old wives! Thanks.