Wiring a van converted into a catering van? Help.

[judd96]

Hello,

I went to go and check some electrics on a friends catering van they have purchased. It's not a towable van, it's a long wheel base with the back converted into a catering van.

Everything was wired in twin and earth, no cpc sleeving, holes in the C/U typical bodge job so I'm going to wire it again.

I will wire in Arctic/tuff flex and use conduit for the drops and fish behind the riveted steel in the top corners if you can imagine coving.

C/U. Will be a 4 way 80a 30ma RCD which is fed from the commando back to back. Feeding a lighting circuit, a water boiler supply, and a 16A or 20A radial circuit for the sockets.

Now with regards to Earthing. I will earth the LPG gas supply and the frame using 10mm is this correct?

What exposed/extraneous conductive parts need too?

The generator should have a neutral-earth link for the RCD to work?

Theres probably a lot of things I have missed, just looking for some advice.

Thanks

 

[James]

Mobile or transportable instalations have there own special regulations section.

cant recall what number it is but I would have a look at the book before ordering or specifying what you intend to do.

 

[davesparks]

What size supply is this designed to be connected to?

10mm seems somewhat big for most catering vans I come across.

 

[R-fur]

The generator will need a neutral earth link. The gas and structural metal work may not require bonding as they are not connected to earth but it would be advisable to earth them. 10mm is probably overkill I would think 4mm would be enough.

 

[Strima]

You'll also need ferrules for the flex cable ends, seems a lot of people miss this out.

 

[Ian1981]

The generator will need a neutral earth link. The gas and structural metal work may not require bonding as they are not connected to earth but it would be advisable to earth them. 10mm is probably overkill I would think 4mm would be enough.

There’s no point earthing them for no reason as they would not be considered exposed conductive parts and earthing them unnecessarily would raise their potential in relation to true earth in the event of a fault, potentially introducing a hazard to someone like a customer stood on the ground and touching the frame of the van.

 

[pc1966]

Mobile or transportable installations have there own special regulations section.

Section 717 (page 298 in the big blue book)

Just looking at it now out of curiosity!

It also mentioned BS 7909 for temporary setups, might be some on-line videos, etc, for that which would be worth a look.

 

[Ian1981]

You'll also need ferrules for the flex cable ends, seems a lot of people miss this out.

It’s wired in twin and cpc unfortunately

 

[pc1966]

It’s wired in twin and cpc unfortunately

I think that was about using arctic cable in the rewire?

 

[Ian1981]

I think that was about using arctic cable in the rewire?

Yeah everything WAS , missed that bit

 

[R-fur]

717.411.3.1.2 says that accessible conductive parts shall be earthed

 

[Ian1981]

717.411.3.1.2 says that accessible conductive parts shall be earthed

Bonded using fine stranded conductors,not earthed

 

[judd96]

There’s no point earthing them for no reason as they would not be considered exposed conductive parts and earthing them unnecessarily would raise their potential in relation to true earth in the event of a fault, potentially introducing a hazard to someone like a customer stood on the ground and touching the frame of the van.

Thanks for the reply. There seems a lot of confusion on the topic that's why I posted the thread. I will opt to use 4mm then, it's just I have some 10mm at home . I will bond the LPG and the chassis and leave it as that I think.

 

[Strima]

It’s wired in twin and cpc unfortunately

That's why the OP is rewiring in flex.

 

[Lucien Nunes]

There’s no point earthing them for no reason as they would not be considered exposed conductive parts and earthing them unnecessarily would raise their potential in relation to true earth in the event of a fault, potentially introducing a hazard to someone like a customer stood on the ground and touching the frame of the van.

That seems back-to-front. If the supply is TN-S from a genny with an earth rod, the installation earth will be approximately at the same potential as true earth even in the event of a fault to CPC within the van, as the rod does not carry the fault current. Therefore connecting the van body to the MET will not significantly increase that hazard. However, in the event of the line conductor contacting the bodywork due to cut or chafed wiring or being pierced by a screw etc, quite a plausible scenario, then if the bodywork is not earthed there will be a full 230V between body and true earth. In any case there will probably be many points of casual contact between appliances and the vehicle, possibly including via gas pipes. I would rather have a solid connection made with a cable.

As far as cable choice goes, how about H07RN-F as a tougher alternative to arctic PVC?

 

[marconi]

I suggest you contact John Peckham of Astute Technical Services. He has produced a specification for mobile catering facilities which meets the regulations.

 

[Ian1981]

That seems back-to-front. If the supply is TN-S from a genny with an earth rod, the installation earth will be approximately at the same potential as true earth even in the event of a fault to CPC within the van, as the rod does not carry the fault current. Therefore connecting the van body to the MET will not significantly increase that hazard. However, in the event of the line conductor contacting the bodywork due to cut or chafed wiring or being pierced by a screw etc, quite a plausible scenario, then if the bodywork is not earthed there will be a full 230V between body and true earth. In any case there will probably be many points of casual contact between appliances and the vehicle, possibly including via gas pipes. I would rather have a solid connection made with a cable.

As far as cable choice goes, how about H07RN-F as a tougher alternative to arctic PVC?

Well no my point was that it’s bonded as per section 717 and not just mearly earthed.
Maybe it wasn’t clearly said by myself

 

[Lucien Nunes]

OK, granted bonding and earthing are defined differently and have different purposes, and I was rather sloppy in my use of 'earthed' to mean 'connected to the MET in some way'. However I understood the post to mean it was desirable not to make any connection between the vehicle body and the MET at all, for which I did not agree with the logic.

 

[Ian1981]

OK, granted bonding and earthing are defined differently and have different purposes, and I was rather sloppy in my use of 'earthed' to mean 'connected to the MET in some way'. However I understood the post to mean it was desirable not to make any connection between the vehicle body and the MET at all, for which I did not agree with the logic.

Yeah I see that , My bad

 

[freddo]

As far as cable choice goes, how about H07RN-F as a tougher alternative to arctic PVC?

This cable is also resistant to hardening from oil and grease if this happens to be a filthy burger van.

 

[Ian1981]

Who doesn’t love an E.coli van?

 

[davesparks]

Thanks for the reply. There seems a lot of confusion on the topic that's why I posted the thread. I will opt to use 4mm then, it's just I have some 10mm at home . I will bond the LPG and the chassis and leave it as that I think.

This sounds far too much like design by guesswork than actually understanding what is needed.

Don't just guess at what needs to be bonded, test it and find out for sure.

If you wish to use 10mm flexible cable then there is nothing stopping you, however the minimum requirement would be 6mm off the top of my head.

 

[judd96]

That seems back-to-front. If the supply is TN-S from a genny with an earth rod, the installation earth will be approximately at the same potential as true earth even in the event of a fault to CPC within the van, as the rod does not carry the fault current. Therefore connecting the van body to the MET will not significantly increase that hazard. However, in the event of the line conductor contacting the bodywork due to cut or chafed wiring or being pierced by a screw etc, quite a plausible scenario, then if the bodywork is not earthed there will be a full 230V between body and true earth. In any case there will probably be many points of casual contact between appliances and the vehicle, possibly including via gas pipes. I would rather have a solid connection made with a cable.

As far as cable choice goes, how about H07RN-F as a tougher alternative to arctic PVC?

Thanks for the reply. I was originally going to use arctic flex. I'm now actually thinking if it's over kill. Everything will be conduit, I'm not running under the unit itself. It's all inside.