"We have a small scale food packaging unit"

It is a small factory or it just a machine for packaging only or are you trying to protect your packaging machine control panel from fire as the results of short circuiting.

Sorry, we couldn't get the idea of your "packaging unit".

It is a small factory.

The circuit protective device needs to be rated at or slightly above the full load current of the packaging unit. Its purpose is to protect the conductors supplying the unit.

The conductors need to be suitably sized to withstand the full load current without excessive voltage drop at the downstream end.

Numerous algorithms for determining the above can be found. Among them is British Standard 7671.

Thanks for prompt response.

Here you go. This company has applications on machine tools, Server farms, Police cars, and military vehicles.

They are really great to deal with.

http://www.firetrace.com/

miles

Thanks for providing the web link which is useful.

There are many different wiring safety standards. In the US frequently NFPA70 produced by the National Electrical Code is used. While there are similarities between all of them, they vary due to a variety of local conditions. (Some possible local conditions are ice expansion, fungal rot, lightning protection.) You should comply with your local standards. Most importantly though you will need somebody authorized by your local boards to verify compliance with your local standards.

If you need clarification or translation of what your inspector or electrician tells you is required, then come back here for an explanation. This forum though is not a substitute for professional help.

Also you should ensure that all cables are passing through conduit pipe and are not loose with tapped joints. All switch gear protection devices are properly selected and of reputed makes such as Siemens, English Electric, L&T make.

Suresh Sharma.