Emergency panel in Hazardous area 1

[Jed057]

anyone can give me the answer.

Regarding Lighting panel was located in hazardous area and TNS system need 3 phase + N ,my question related to all power incomer cable need to have switch for cut neutral cable or not,
If switch incomer only 3 Pole and no switch at nutral ,Is it dangerous ?

 

[sberbece]

Jed057,
Any 3 Ph. electrical feeder that supplies a load situated in a hazardous area shall be equipped with a 4 poles switching device.
This is to mitigate the hazard that may appear due to accidental existence of potential difference between neutral and earth, which can represent a source of ignition (i.e. a spark capable to ignite the flammable surrounding atmosphere).