Electrical Inspection & Testing
Outdoor Broadcast Units
The term ‘unit’ is intended to include a vehicle and/or transportable structure in which all or part of a low voltage electrical installation is contained, which is provided with a temporary supply by means of a plug and socket-outlet, for example. The units are either of the mobile type, such as self-propelled/towed vehicles, or of the transportable type, such as containers or cabins.
Examples of such units include:
- outside broadcast units as used in the entertainment industry
- medical services such as blood donor or mobile breast screening units
- advertising trucks and "roadshow" vehicles
- fire fighting appliances
- mobile workshops
- modular office buildings and construction site huts
- transportable catering units and fast food vans
It is important to note that the following are not within the scope of Section 717 of BS 7671:2008:
- transportable generating sets (Section 551)
- marinas (Section 709)
- pleasure craft (IEC 60092-507)
- mobile machinery (BS EN 60204-1)
- caravans and other leisure accommodation (Section 721)
Risks
BS 7671 covers electrical installations generally and, as with all special locations, where particular risks exist, additional measures for protection are to be applied. In some instances in may be necessary to refer to other Sections of Part 7 of BS 7671, where in the case of, for example, units incorporating showers are utilised.
The following are examples of particular risks associated with mobile and transportable units:
- loss of connection to earth
- different national and local electricity distribution networks
- impracticality of establishing an equipotential zone external to the unit
- open-circuit faults of the PEN conductor of PME supplies
- shock due to high-protective-conductor currents
- vibration whilst the vehicle or trailer is in motion
Verification
The frequency of inspection should be assessed by a competent person who is aware of the operating conditions for that vehicle. Some trucks could be static for long periods whilst others may be moved from location to location on a daily basis so it is important to assess the risks associated with different units.
Minimally, the unit should be inspected and tested annually, with a Periodic Inspection Report obtained on its condition and the necessary maintenance work implemented.
A visual inspection should be carried out on the connecting cable and all plugs and socket-outlets before each and every transported use of the unit. The results of the visual inspection should be entered in a log-book as a permanent record of the condition of the electrical equipment.
ESI: Electrical Safety Inspections Limited are able to assist with all types of electrical inspection and testing, issuing both NICEIC Periodic Inspection Reports and PAT Testing certification.