BS 7671 Section 717 - Mobile or Transportable Units. Applicable to refrigeration trailers?

Question

Does a refrigeration trailer that is utilised to transport food goods between the clients depots and is then connected into the sites electrical supply through a trailer hook up connection unit to facilitate running of the refrigeration equipment classified as "Mobile or Transportable Unit" and therefore warrant the requirements of BS 7671 Section 717? 
 The trailer will maintain the connection to the sites power supply for a few hours to facilitate loading/unloading.

The regulations now adds further detail for PME installations, where it can only be permitted if one of the below applies:

Would part (ii) be a satisfactory measure in the above scenario for a PME supply?

gkenyon · Accepted Answer

This is not an easy question, because the actual unit itself in this case may comprise only Machinery as defined in the Supply of Machinery (Safety) Regulations, which is outside the scope of BS 7671, and BS EN IEC 60204-1 applies. However, the connection of the Machinery to the electrical installation is referenced out to BS 7671 (IEC 60364 series) from BS EN IEC 60204-1. So certainly, 717.411.4 would apply, if not other parts of facilitating the connection in 717. 
 Daniel Hickson said: Would part (ii) be a satisfactory measure in the above scenario for a PME supply? 
 Yes, if the unit is located within, or outdoors on an upper storey or roof, of a building or structure containing the electrical installation that supplies the unit, PME can be used. Precautions should be taken to prevent the connection of a unit outdoors. 
 These type of unit would usually be used in a place of work, so when looking at a connecting point (e.g. suitable socket-outlet), you would need to involve the duty holder in respect of risk assessments, because they will be managing ongoing safety.

gkenyon · Answer

Patrick Benson said: Also, would the use of a O-PEN protection device permit the use of the PME supply? Any comments would be much appreciated. 
 Not according to BS 7671. 
 An open-PEN protection device switches the protective conductor . According to BS 7671, a protective conductor may only be switched: 
 
 Where permitted by Regulation 543.3.3.101; or 
 Where an open-PEN protection device (OPDD) is used for an EV charging equipment installation (see 722.411.4.1). 
 
 Since connection of a mobile/transportable unit is neither of the above, use of an OPDD would NOT conform to BS 7671. 
 The same situation exists where an OPDD is considered for use for a heat pump or other fixed electrical equipment ... usually, the device contravenes BS 7671 (Regulation 543.3.3.101). The sole exception of the device being specified for EV charging equipment installations (722.411.4.1). 
 Even where 722.411.4.1 applies, it is only the charging point that is specified for protection by the OPDD.

BS 7671 Section 717 - Mobile or Transportable Units. Applicable to refrigeration trailers?

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