If flammable gas or vapor levels (greater than 10 percent of the LFL of the substance) are present or expected to be present all electrical equipment shall comply with the requirements of National Electrical Code, (NFPA No. 70), for hazardous classified locations and bonding requirements of Article 250 of the National Electric Code. Please specify the voltage requirment. Is only 24 supply allowed inside? how to do grinding activity? whether 110 v with elcb allowed in a confined space for work. weldind ( DC) current what r the control measures required to prevent harm of people.

Safetycool - you need to give us more information. NFPA codes are american - are you seeking compliance with american laws? If you are welding then you already have a source of ignition, whether the electrical apparatus is intrinsically safe or not. You ask about the voltage - is this a conducting environment? In which case, the open circuit voltage of the welding set will need to be very low to avoid fatality. Could you describe what you are doing, and what the flammable gases/vapours actually are?

yah i m sorry not to provide more information. i m worried to protect workers from conductivity. so i need guidence on electrical supply requirements. The confined space is a vessel ( read Metal)designed to handle extreamly flammable chemicals. To drive off flammable chemicals adequate measures taken and it is positively isolated,intered, purged to be gas free. Continous gas monitoring will also be done to monitor the work location.

You are still confusing me. If it were welding in a conducting environment, the British Standard is to keep the open circuit voltage to no more than 48 V rms or 113 V DC. The equivalent American Standard is 38 V rms and 50 V DC. So I guess this is a starting point. If you are not welding, and you are using a pneumatic grinder, what electrical apparatus are you using??

I would say the original poster is not in the UK, due to quoting US standards, so none of these are relevant. There might be local equivalents / US standards

thanks for the valuable help.Electrical supply will be required for lighting and it will be 24 volt only. initially it is decided to use 110 v Grinder to carry out grinding activity and during risk assessment it is decided to utilize pneumatic grinder to reduce risk of electrocution at low level.