Static or not

[Engineer54]

im with you spin, i say ya can tp-q-s as there permenant. you clever chap

If you or Spin can show where it specifically states that a caravan/mobile home (built to the same construction methods as a touring caravan, ie ..Metallic skinned) can be connected on a permanent or temporary basis to a PME (TNC-S) then fine!! But until then, i believe that the exclusion of PME stands for both types of caravan/mobile home's....

The permanent buildings on these park sites relates to the conventionally built club house's, shops, shower blocks and the like... Nothing with wheels on it ...lol!!!

 

[mike22861]

I think it comes down to the terminology I wouldnt expect a caravan fed by a 16A supply to be a permanent residence on our site we have 3 categories permanent residences fed by 63A non RCD supply just as a DNO would supply to a house, permanent sited but not permanent residence supplied by 32A 30mA rcd feed and temporary sitings fed by 16A 30mA rcd feed I would class the 63 supplies as ok for TN-C-S and the rest as not. I still maintain the more earth you can get the better don't be fooled by RCD protection.

 

[nickblake]

Mmm i have to agree with Engineer 54 on this one , its the structure that causes a problem wether it moves or not its still cladded in metal , have you ever tried to open a caravan door when its been connected to a TNCS supply with a neutral fault a nice 120 volt belt which is above the safe voltage so dangerouse ,and its for this reason the supplies have to be TNS or TT

 

[Deleted member 26818]

If you or Spin can show where it specifically states that a caravan/mobile home (built to the same construction methods as a touring caravan, ie ..Metallic skinned) can be connected on a permanent or temporary basis to a PME (TNC-S) then fine!!

I believe that the quote from BS7430, does just that.

 

[Engineer54]

I believe that the quote from BS7430, does just that.

You mean as you quoted above ?? If so, i don't think so. I believe the ''permanent'' buildings they are referring to, are the conventional type buildings found on these caravan/mobile home parks.... Not the over-sized caravans (30 odd feet long) they call mobile homes, complete with wheels. They are built in the same type of construction method as touring caravans, using the shell as part of it's overall integral frame strength.

Now if your talking about the other type of mobile home, those that can be split and moved on low loaders. Fine!! They are wood or composite material framed based, and therefore wouldn't have any restriction as to what type of electrical supply can be provided....
They don't come with wheels either. ...lol!!

 

[mike22861]

Actually all the caravans I am referring to are the 30ft variety touring caravans have to be fed by 30mA rcd supplies no more than 3 to an individual RCD and for info even the 3 bedroom 2 bathroom log cabins have wheels although we remove them after siting and we feed them with 32A non rcd supplies as they have their own split load dist boards fed from a T-N-S system.

 

[IQ Electrical]

Shouldn't each socket-outlet have individual RCD protection?

Spot on, the RCD should disconnect the neutral too.

Just to clarify though, the requirements of section 708 and 721 do not apply to mobile homes or residential park homes or transportable units.

 

[mike22861]

Yes I should have pointed out they are 2 pole RCDs not single pole RCBOs it's also quite unnerving how many times i get asked if an RCD rated at 63 or 32 amps etc is also an MCB to I just sigh and point out its the current rating for max in use amperage and suggest they may try a different job.

 

[Deleted member 26818]

I'm sorry, but this is a British Standard, they don't use a word for one thing, then use the same word for something else entirely different.
This section is headed 21.10 Mobile (touring) caravans and caravan parks.
I would not accept that a mobile home designed to be split and then transported on low loaders as being a Mobile (touring) caravan.
Now in my experience, these British Standards usually define the terms and nomenclature used.
Here is the definition of a caravan as defined by BS7430:
3.2
caravan
trailer leisure accommodation vehicle, used for touring, designed to meet the requirements for construction and use of road vehicles

I don't belive that a mobile home designed to be split and transported on low loaders would meet the requirements for construction and use of road vehicles.
I further don't believe that after having defined the meaning of the word caravan, that the Standard would then use the word for anything other than as defined.
As such where the word caravan is used in the note, it is refering to one with wheels and is designed to be towed behind a vehicle.

 

[IQ Electrical]

Spin, if you were responding to my post on exemptions, I was quoting from Guidance Note 7.

 

[Deleted member 26818]

Spin, if you were responding to my post on exemptions, I was quoting from Guidance Note 7.

No I was responding to Engineer 54.

 

[Engineer54]

Spin,

I am thinking purely from a logical stand point. A mobile home is of the same construction as a touring caravan, both use the metallic shell as the main strength of it's frame. If you exclude one (touring caravan) from the use of a PME derived supply because of enhanced hazard, because of it's construction method, then the surely the other type, (mobile home) will have exactly the same level of hazard as the touring caravan.

The fact that it's sited on a semi permanent location is, or should be irrelevant, the perceived hazard remains the same. Now if you are right, and these over-sized caravans ''Can'' be connected to a PME supply then we have yet another contradiction within BS7671.

By the way, ...Rarely are these 30+ feet mobile homes transported on it's own wheels, behind a towing vehicle, they are generally transported on low loader trailers, just as the split mobile homes are.

 

[Deleted member 26818]

It's not the construction that is the hazard, but the method of connection.
A touring Caravan, or Motor Caravan is designed for an ordinary person to connect and disconnect from a pitch connection.
Whereas a Mobile home, Residential Park home, or (as refered to in BS7430) residential Caravans which are not normally intended to be moved, are not.
When a touring Caravan or Motor Caravan is connected to a pitch supply by an ordinary person, there is no I&T conducted to ensure disconnection times are met, that protective conductors are continuous, there is no check to ensure extraneous-conductive-parts are bonded etc.
Wheraes when a Mobile home etc. irrespective of it's method of construction is connected, just as when a connection is made to a brick built dwelling, a competent Electrician should be involved, and appropriat I&T should be conducted.
As such the requirements of Section 721 are not applicable.
I was not aware when I posted the quote from BS7430, that the Caravans in question are not the touring type, but are Residential.
However such would explain why in the past, no special considerations have been made, the Regulations don't require any.

 

[mike22861]

Just as a point mobile homes semi permanent are required to have a PIR or in new parlance an electrical condition report when they are moved and reconnected they are also required to have an annual PIR if they are to be hired.All mobile homes we site are given a PIR after connection. It's amazing how many times RCDs fail testing, on a caravan site there are probably many many more RCDs than domestic guys come across.I wouldnt trust my life to an RCD. Just as an aside to BS7671 I have a system that runs 600v chopped DC at 20KHZ in water it is protected by a 9mA earth leakage detector and a continuous insulation test that trips if below 1.5Mohms. Would you go near it if protected by a commercial 30mA RCD

 

[Engineer54]

It's not the construction that is the hazard, but the method of connection.
A touring Caravan, or Motor Caravan is designed for an ordinary person to connect and disconnect from a pitch connection.
Whereas a Mobile home, Residential Park home, or (as refered to in BS7430) residential Caravans which are not normally intended to be moved, are not.
When a touring Caravan or Motor Caravan is connected to a pitch supply by an ordinary person, there is no I&T conducted to ensure disconnection times are met, that protective conductors are continuous, there is no check to ensure extraneous-conductive-parts are bonded etc.
Wheraes when a Mobile home etc. irrespective of it's method of construction is connected, just as when a connection is made to a brick built dwelling, a competent Electrician should be involved, and appropriat I&T should be conducted.
As such the requirements of Section 721 are not applicable.
I was not aware when I posted the quote from BS7430, that the Caravans in question are not the touring type, but are Residential.
However such would explain why in the past, no special considerations have been made, the Regulations don't require any.

Well explained Spin....

And there was i, thinking the exclusion was down to the enhanced hazard of a faulty neutral earth on a caravan/mobile home, that is basically totally enclosed in a metallic shell!!