Cabling underneath Static caravan

[MuttonJeff]

I need to put in an extra sockets in a static caravan. The easiest route is to run from an existing socket in the ring, through the floor, under the caravan and then up to the new socket position. Could anyone tell me whether the run under the caravan needs to be in SWA or can I use rubber flex as the run will effectively be under the floor - though the van is on a hill and one end is around 4ft off the floor and therefor accessable from outside by bending or by a dwarf? (will in done in 2.5mm)
Thanks

 

[RF Lighting]

I would think you ought to have some sort of mechanical protection for the cable to prevent damage by prescence of flora or fauna.

Caravans are special installations which I have no experience of working on. I'm sure someone on here will know the conventional way this would normally be done.

 

[ericmark]

You need to consider rodent attack but normally it is just wired in blue 2.5 flex. The RCD has to be twin pole and you can't use twin and earth and it does say flex so that also rules out SWA so although the PVC insulated & sheathed Controlflex Type 'SY' Steel Braided (coloured cores) could be used as that is considered flex.

 

[Lectrician]

Arctic flex is NEVER used for wiring to the fixed install of a caravan, static or otherwise.


I would use standard T+E and provide additional mechanical protection with MMT2 trunk or similar. If the static van is on a concrete hard standing, I would be inclined to simply clip direct to the timber joists that usually rest on the steel sub frame.


Some van manufacturers use FP200, so it may be prudent to extend with this.

 

[Pensdown]

I need to put in an extra sockets in a static caravan. The easiest route is to run from an existing socket in the ring, through the floor, under the caravan and then up to the new socket position.

Because the wife has just adopted the "eyes closed fly catcher position" I've had a quick read through section 721. I can't see any reason why can't run through the floor and under the caravan. However, you must protect the cable from mechanical damage where it passes through the floor.

Could anyone tell me whether the run under the caravan needs to be in SWA or can I use rubber flex as the run will effectively be under the floor - though the van is on a hill and one end is around 4ft off the floor and therefor accessable from outside by bending or by a dwarf? (will in done in 2.5mm)

721.521.2
You could use SWA but it must be stranded and have a minimum of 7 strands/core.

You can also use a sheathed flexible cable which includes PVC and rubber flex to BS-EN 60332-1-2 If you're protecting the cable it must be in non metallic conduit.

You can also use flexible singles in conduit.

But due to vibration, you can't use any cable with a solid conductor. If you want to use T&E it must be stranded.

721.522.7-8 Vibration.

In summary you must protect the cable from mechanical damaged caused by vibration. Unless you enclose the cable in plastic conduit it must be supported at intervals not exceeding 0.4mtrs vertically and 0.25mtr for horizontal runs. This is over the entire run. So no running up in cupboards un-supported

If you want it mechanically protected I would use an SY cable but if your not bothered just use a sheathed flexible cable as above

 

[ericmark]

Lectrician how can you wire with T&E and comply with 721.521.2 The wiring systems shall he installed using one or more of the following:
(i) Insulated single-core cables. with flexible class 5 conductors, in non-metallic conduit
(ii) Insulated single-core cables, with stranded class 2 conductors (minimum of 7 strands), in non-metallic conduit
(iii) Sheathed flexible cables.
All cables shall, as a minimum, meet the requirements of BS EN 60332-1-2.
Non-metallic conduits shall comply with BS EN 61386-21.
Cable management systems shall comply with BS EN 61386.
Since when has T&E been flexible?

 

[Lectrician]

You guys are confusing STATIC vans with CARAVANS.

You wanna go look in the definitions section. don't go jumping feet first into the regs.

 

[ericmark]

While working on Sizewell B power station I inhabited the family caravan for 4 years it was 16.4 foot long and was able to be towed with a car on that site there were many more workers some with really big caravans all able to be towed and classed as a caravan and all would come under section 721 there was one guy who had a mobile home which unlike the caravans could not be towed and would need to be transported on a lorry it also had all the winterising work and plumbing and was supplied with a 32 amp rather than 16 amp supply and was hard wired not plugged in but was always referred to as mobile home not a caravan and was on a hard standing which would not allow any flexing of the structure. Although the BS 7671:2008 does say that 721 does apply to those electrical circuits and equipment intended for the use of the caravan for habitation purposes this refers to the design not the use and were designed to be towed then 721 will be active and Part P will not. Remember if designed for habitation purposes then it would require planning permission and be classed as a building so would come under Part P and because of the food preparation area and provision of sink nearly all work would be reportable. The whole reason for flex is that van flexes and I would say if there is any flexing in the van then use flex only if rigid would I consider using any other cable and considering you could if you wished wire a house in flex than I can see no problem.
Eric

 

[MuttonJeff]

Thanks for all your comments - very useful,
The caravan is static and other services are hard wired to it. i.e. it would take a bit of disconnecting to move the thing, The van is also not towable, but I guess is moved on the back of a lorry (but will be there for another 8 years till it's lease is up)
Think it's probably easiest to run it in flex and mechanically protect with pvc conduit.

 

[ericmark]

Pure interest I knew some one on Falklands we called MuttonJeff could it be you?

 

[MuttonJeff]

No, not me

 

[ericmark]

What is a caravan? Of interest only not trying to have a go at Lectrician as it did make me go and research what a caravan is and I have make some mistakes:-
A trailer leisure accommodation vehicle, used for touring, designed to meet the requirements for the construction and use of road vehicles.
Not for habitation purposes.
To be for habitation it must have an adequate piped supply of wholesome water a suitably located water closet for the exclusive use of the occupants for the exclusive use of the occupants (if any), a suitably located fixed bath or shower and a wash hand basin each of which is provided with a satisfactory supply of hot and cold water and it has an effective system for the draining of foul water and surface water. This was taken from Portsmouth City Council web site but I would suspect the same definition would apply nation wide.
So a touring caravan is not for habitation unless water and drains are connected.
MOBILE OR TRANSPORTABLE UNITS however do have some common rules with caravans so also one must look at Section 717 and the Mobile Home it seems would come under that section. So 717.52.1 Flexible cables (for connecting the unit to the supply) in accordance with H07RN-F (BS 7919), or cables of equivalent design, having a minimum cross-sectional area of 2.5 mm² copper shall be used. The flexible cable shall enter the unit by an insulating inlet in such a way as to minimize the possibility of any insulation damage or fault which might energize the exposed-conductive-parts of the unit. Will apply and guess what that is even more restrictive than the one for caravans.
I realise 521.9.3 A flexible cable or flexible cord shall be used for fixed wiring only where the relevant provisions of the Regulations are met. But as yet I have not worked out what the relevant provisions are may be you would like to enlighten me.
The BS 7671:2008 regulations are complex and I would not profess to know them all so in the main look at what would make sense and any portable building will flex and so wiring it in cable that will also flex makes sense.
I have made mistakes and I will admit it when I have but here I think I was right to advise on flex although if you can quote any regulation which says otherwise I will take notice.
Eric

 

[MuttonJeff]

The cable runs are pretty short, so may as well use flex in trunking just in case - extra cost is negligable.
Is stranded SWA considered to be flex though?, I guess the armour makes it less than flexible, though in a vibration situation the cores would be fine. As long as its 3 core.
Static caravans seem to be a bit of a grey area! - Will update this thread though when I find out more.

 

[ericmark]

Have you looked at http://www.batt.co.uk/products/index.asp?area=2&p1=50&p2=151&p3=428
This is flex and still SWA but Braided used a lot in food industry.
Eric

 

[MuttonJeff]

Thanks - I had a reply from the Elecsa tech help regarding this and they suggested SY cable. SWA is not regarded as flex even if stranded 3 core.
thing is the glands for this are £15 a pair! - which is more than the cost of the cable run!