The local council classifies us as a Mobile Home Site probably due to the fact everything comes under the Mobile Homes Act 2013. The site owner is struggling to carry out an EICR which is part of the site license agreement with the council. The previous report was classed as satisfactory but had listed that some RCD test buttons had failed and coded C3. One of them being mine which was replaced with the different manufacturers 100mA  RCD in place of the 30mA, hence my question here. Ideally I would prefer a time delay 100mA as I have DP RCBO’s in my consumer unit. 

I would think the licensing would just state to BS7671 and the site owner would just trust the electrician’s judgment and use them as the scape goat if anything happens. Perhaps the 708 scope could be worded better as to whether it applies to homes covered by the Mobile Homes Act or not, which then makes it very easy to clarify. 

I think the true definition of mine is a Static Park Home but the wheels must still be in place but it’s on stands and has a brick surround so it can’t easily be moved. Interesting on the Part P side as you would have thought it would apply for these type of homes. 

Colin Haggett said:

Perhaps the 708 scope could be worded better as to whether it applies to homes covered by the Mobile Homes Act

I know this perhaps seems pedantic, but please bear with me.

Section 708 clearly doesn't apply to the 'residential park homes' themselves (as Note 3 in the Scope, Regulation 708.1) ...  I think what you're asking is whether Section 708 scope could be re-worded to say whether it applies to sites that only contains homes covered by the Mobile Homes Act?

I'm not sure that is possible. I understand that sites covered by the Mobile Homes Act can include provisions for caravans and motor caravans (and therefore be a "caravan site") so perhaps that simple exclusion is not possible? I'd again be suggesting this is a question for the site owner/operator to address.

Colin Haggett said:

Ideally I would prefer a time delay 100mA as I have DP RCBO’s in my consumer unit

I fully understand that ... whilst BS 7671 requires that the RCD in question is accessible to the user of the "pitch" (the "consumer" in Regulation 708.415.1), I take the point that scratting round outside  in bad weather on a dark night isn't ideal if the installation is subject to unwanted tripping.

These units are delivered to site on the bed of an HGV. From the HGV they are wheeled by aid of tractor or similar to the pitch. The pitch may be hardstanding concrete, gravel or earth. By the side of the pitch is the external supply position.

The manufacturers provide a plug for connection to this supply point. Often a 16 A or perhaps a 32A  60309 plug connected to a flex that runs into the van. Sockets require additional protection by way of RCD and the pitch supply position provides such by way of 708.
The flex runs up into the van to the internal consumer unit within the walls of the van, this would require additional protection by way of RCD.
The manufacturer builds perhaps 1000's of units that will be sited and connected to a supply unknown to them. Without 708.1 what would they do?

The pitch power supply position is set up to cater for a statics but such could be of all ages and change throughout the life of the pitch. Without 708 what would you have?

As I have said several times in this thread, 708.1 applies to the distribution system on that site NOT the home sited. The home is caught under the general mass of bs 7671.
On these caravan / leisure accomodation vehicle sites a range of units could be positioned and such need safe electrical systems. This is where electrical engineering judgment kicks in, it kicks in against the distribution system on that site and the mix of units / vehicles / homes that are manufactured to an industry spec knowing they can be supplied safe for continued use once sited. Without 708 we would not have this.

Perhaps one answer lies with the licensing authories who need issue licence for each site. They under consultation with suitably experience  electrical engineers / designers designate by way of licence if the requirements of 708 apply to the site or perhaps suitably segregated sections of that site. The connection to these units by way of the distribution system shared is the point of relevance.

Without such a licence framework or the seemingly catch all of 'similar' in 708 there would be manufacturers supply units that require additional protection rcd's but onsite are pitched without.
Same applies to those whom  purchase a secondhand unit and site on a pitch owned by a site owner more often than not with no electrical knowledge. It is a dynamic environment that must be kept electrical safe and 708 ALONG WITH sound engineering decisions can achieve that. 

708.1 relates only to the distribution circuits.

I'm not sure I follow your thinking. Caravan parks in general certainly contain final circuits (by definition whatever supplies a socket outlet, such as on a EHU, must be a final circuit, ditto any site lighting circuits) - and many of the provisions (e.g. 708.415.1) explicitly mention final circuits and others (e.g. 708.521.7.2 for depth of buried cables) must surely apply to final circuits just as much as distribution circuits. It may be that in the case of the usual EHU box, the final circuit to the socket is entirely contained within that box, but it's still there and still part of the site's installation, to my mind.

I can see the point that a caravan connected via a bit of flex that's directly terminated into the box rather than by a commando plug & socket could be argued as not being a final circuit (by the normal definitions at least, but wording of the 2nd paragraph of 708.415.1 would seem to assume otherwise). I suppose it depends on whether you consider a caravan as a whole as being an item of current using equipment. (Whatever's inside the caravan is out of scope of the park's installation after all). We've had the same debate over 19" racks which may have their own internal power distribution & protective devices.

Having seen quite a few statics that are connected by a length of arctic flex - sometimes by plug & socket to a tourer type EHU, sometimes with just a stuffing gland into a very similar type of box, I do take Mike's point that the risk to the flex (e.g. from grass cutting machines) in the fixed connection case is pretty much identical to the plug & socket case - so 30mA RCD additional protection would be sensible. SWA direct into the home, would be much less of a risk.

   - Andy.

Andy you are quite correct and it was indeed the note under 708.415.1 that was in my mind and lost in my sloppy definition.
By that I mean the hook up point / external electrical supply point which supplies the units, positioned often aside the lodge static is part of the distribution assembly. Thanks to the regulation the 30mA rcd is in place at the end of the distribution position ready for final connection. This becomes a uniform known position against which the units to be sited can be manufactured against. It is the position adopted by site owners in that they take responsibility for the electrical services only up to this point of connection. From that point on it is the owner of the units responsibility. Certainly on E.I.C.R.s  of the caravan I would include the flex and plug to the hook up / connection position.

With these units the site network operator does not bring a supply direct into the unit terminating in a service head. It will often be a looped supply to an external position and from this point the static / tourer / residential home is connected.
708.521.7.2 which you mention refers to the underground distribution circuit that would feed the pillar.

So yes 708 does give mention to final circuits but it is my understanding this helps define the distinction between the distribution assets within the designated licensed area that is the site (could be wrong of course and often pleased to be so).