SWITCH GEAR--HOUSEING SOCITY

They are called NEMA switches in the USA. I live in Florida and the switches are used to automatically switch to a backup generator.

They are expensive for single phase, so I imagine 3-phase is going to be costly since they are designed to handle a lot of current.

there might be a problem in your transformers, you might as well activate your genset to restore your lightings, jumpers is too risky for you and to the building circuitry. better contact a qualified electrical engineer for the troubleshooting required. trace the current from your main supply, down to your main distribution panel for a thorough system check.

No

each phase is ideally supplying 1/3 of the power, the remaining phase will probably not be able to deliver the amount of current [power].

there is also the matter of equipment that require 2 phases, the 440volts won't be available.

better to solve the problem causing loss of phase(s)

a back up generator would work, but is probably cost prohibitive.

U can use Auto Matic Transfer Switch which automatically switches to backup generator when the supply is gone and to normal supply hwen it is restored ..

I would summarize the answers (and agree myself) to the following:-

1) Do not install Nema(?) switches, the most usual effect would be that the last phase would be overloaded and also pop off ! Net effect would be that the whole building is then in darkness....

2) Install DG, suitably sized for the whole building and with automatic start up and switch over. Expensive but effective. A 3 Phase DG would make installing easier than a single phase I would imagine.....but it depends on the cost of the DG and/or the switching equipment....

If this is a industrial building and at times may call for three phase wiring, your motors will not run. We normally have two different supply lines entering our facilities. If one line surges or drops a phase it automatically switches to the other service.

Jumping a phase is a definite NO NO. If you only have voltage on one line of a two or three phase component, current surges occuring on the live line may overload and cause wiring or component burn out unless each is protected by a overcurrent device.

Be careful to not backfeed the lines aswell!