Some and single and some double pole and some not switched, it is common to use a non switched to supply items like washing machine, oven, tumble drier mounted under counter often with a separate switch above the counter, the use of single pole switching can cause problems with earth - neutral faults, in the UK caravans are a special case, with boats and petrol stations TN-C-S supplies not allowed, so in the main this means TT, so need to be double pole due to being TT, there has been a change I think, Mobile Homes were not considered as caravans, I think that has changed this year.
132.14.2 No switch or circuit-breaker, except where linked, or fuse shall be inserted in an earthed neutral conductor. Any linked switch or linked circuit-breaker inserted in an earthed neutral conductor shall be arranged to break all the related line conductors.
In a TN-S or TN-C-S system the neutral conductor need not be isolated or switched where it call be regarded as being reliably connected to Earth by a suitably low impedance. For supplies which are provided in accordance with the Electricity Safety, Quality and Continuity Regulations 2002, the supply neutral conductor (PEN or N) is considered to be connected to Earth by a suitably low impedance. Amended July 2008
There are a host of referances to neutral and earth, and the electric vehicle seems to have caused problems, never before have I seen it where the earth is switched, the TN-C-S supply seems to be causing a problem, although rare, the PEN can be lost, so we have a problem once outside of the equipotential bonding zone. We are seeing there is a real problem in the garden, or any other area outside the zone, so the rules seem to be changing, I don't have latest edition, and it takes some wading through, and we have seen requirements being clarified, which is a real problem, the BS 7671 has always stated the date when it comes into force, and points out it is not retrospective. That is OK for some thing new, but when it clarifies, then clearly the regulations was there before, just not written in a way people understand, so "Every installation shall be divided into circuits, as necessary, to: (iii) take account of danger that may arise from the failure of a single circuit such as a lighting circuit (iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation, has shown the RCD was considered as forming a circuit, but since this has been reinforced, and it brings into question is a duel RCD consumer unit complaint.
However "The Regulations are non-statutory. They may, however, be used in a court of law in evidence to claim compliance with a statutory requirement." so since non statutory if we don't comply that in its self is not a crime.