There are some transfer devices bearing markings such as â€śSuitable for service useâ€ť which is an American NEC marking not applicable in Ontario. Manual transfer devices approved for service entrance use in Ontario shall be approved to CSA Standard C22.2 No 4, shall be marked â€śSuitable for use as service equipmentâ€ť (note the subtle difference in wording), shall meet the OESC definition of a Service Box (switch & fuse, or
circuit breaker), and shall have the neutral assembly bonded to the enclosure with provision for separate connections of the line and load neutral conductors and the service ground conductor.
A pole top switch may also be located on the supply side of a consumerâ€™s service entrance provided it is installed in accordance with OESC Section 75.
Under no circumstances shall a generator be connected to any portion of a wiring system
except where it is connected through a transfer device that makes it impossible for the generator to feed back into the normal power supply. [Ontario Electrical Safety Code (OESC) 6-106, 14-612, 75-608].
Where a double throw transfer device is mounted at a service entrance, the transfer device shall be located on the load side of the service entrance switch [OESC 75-608 (3)(d)], except as follows:
A transfer device may be located on the supply side of an existing consumerâ€™s service entrance at a building provided:
Â· it is approved for service entrance use [2 -034].
Â· the consumers service ground conductor connection is relocated to the transfer device and the neutral bond screw or jumper in the existing service box is removed. [10-
Â· a bond conductor is present between the new transfer device and existing service
Â· this transfer switch shall be treated as the consumers service box for code
Electrical safety Authority