All electrical systems used need to be installed by a competent person to a safe and suitable standard, eg BS 7671 and BS 7909. BS7909 requires all temporary electrical systems to be tested and adequately protected, under supervision by the designated responsible person for the system. The responsible person must be competent and able to manage the system. If work is outside of their competence level, then they should state this and not accept the work.

See our guidance below.