Connecting the generator

Connection methods

The TB allows us to either plug into a socket on the genset (if it has sockets); or to connect to terminals within the genset.

At the installation end, we’ll be connecting into the same terminals we removed the normal supply from.

Keep these conductors as short as practicable.

One method that must NEVER be used is connection by a flex with a plug at each end; one end plugged into the generator and the other into a socket in the installation. These are widely known as “suicide leads”; for good reason. Using them is very unsafe, and completely illegal

Earthing

There MUST be an earth conductor between the genset and the installation’s earthing system. But this can be the PEC of whatever cable we use for the load conductors.

There is NO need for the generator to have it’s own electrode or any other connection to the mass of earth.

Conductor size

The conductors used to connect the generator to the installation need to be heavy enough to carry the load that will be supplied.

Overload

And they need to have overcurrent protection – this can be either at the upstream end (at the genset) or downstream (in the installation). Most gensets will have some form of over-current protection built in. Bit we need to check it to ensure that it will protect the conductors we’re using to make this connection to the installation. And if it is rated too high; either upgrade the conductors or install a protective device.

Short-circuit

They also need short-circuit protection; unless installed in such a way as to minimise risk of short circuit. Short-circuit protection must be at the upstream (generator) end. Bearing in mind that small generators generally can’t provide enough current to meet trip-time requirements for short-circuit protection by over-current device. So it would be wise to provide very good protection against mechanical damage for these cables. NOT just a bit of flex lying on the ground.  Clause 2.6.7 of AS/NZS 3010:2017 provides guidance. 

If the part of the installation needing emergency supply is normally supplied from a DB; then you can connect the generator at the DB as if it was the main switchboard. Instead of removing supply fuses (as for mains); isolate & secure the submains at source, and disconnect them from the DB. While AS/NZS 3010:2017 has extra requirement for connecting an alternative supply generator at a DB; these requirements don’t apply when we’re working under the TB guidance.