A contractor has provided the single-phase electrical installation in 12 new, very small, individual commercial units. For whatever reason he provided two 6way distribution boards one appears to be for lighting and the like and the other for power, both with 30mA overall RCD protections both boards have a main switch. The tails for both boards are brought to a set of ISCOs from which he left a short tail connection for the meter. Now 4 of the units have been connected to the supply but apparently connection is being refused to the remaining units as no main switch has been provided. I guess different DNOs, different rules and indeed attitudes but I can find no reference to the need for a main switch in the DNO connection guide other than that the installation has to comply with 7671.
FWIW, 537.1.4 has migrated to 462.1.201, but the words remain the same.
It is interesting Chris that 462.1.201 refers to a main linked switch or circuit breaker, both singular terms not plural. This device to be positioned as near as practicable to the origin of every installation. It must be double pole switching for ordinary folk for a single phase installation and be capable of switching the supply ON LOAD.
This "isolator" must be able to disconnect when carrying a full load current. So it is more than an "isolator" as defined on page 31 which can also be called a "disconnector." A "disconnector" is defined on page 27 in note 2 as being able only to be capable of opening or closing a circuit when either a negligible current is broken or made, or when no significant change in Voltage across the terminals of each pole of the disconnector occurs."
So the device is a "SWITCH, LINKED" as defined on page 37, even though it affords "isolation". So it is best not to call it an "isolator."
FWIW, 537.1.4 has migrated to 462.1.201, but the words remain the same.
It is interesting Chris that 462.1.201 refers to a main linked switch or circuit breaker, both singular terms not plural. This device to be positioned as near as practicable to the origin of every installation. It must be double pole switching for ordinary folk for a single phase installation and be capable of switching the supply ON LOAD.
This "isolator" must be able to disconnect when carrying a full load current. So it is more than an "isolator" as defined on page 31 which can also be called a "disconnector." A "disconnector" is defined on page 27 in note 2 as being able only to be capable of opening or closing a circuit when either a negligible current is broken or made, or when no significant change in Voltage across the terminals of each pole of the disconnector occurs."
So the device is a "SWITCH, LINKED" as defined on page 37, even though it affords "isolation". So it is best not to call it an "isolator."
