Posted By Guderian Obviously by the fact that you are using cutting torches etc, its not the explosion/fire risk they are worried about, when working inside the cleaned up/declassified fuel tanks. Therefore, it must be the elctrocution risk posed by 110v as opposed to 24volts. Using 110v is one of the main reasons its used, to reduce the very risk of electrocution. Being 110v,, there is in fact 55v rms, if my memory serves me correctly. Provided the 110v equipment is of the correct type/suitable cable etc for the harsh environment, RCDs used/earth leake trips used then the electrocution risk should be minimal. As ever, it should come down to risk assessment, off setting the 110v risk compared to the risks introduced by other means of power - air will probably be noisy, possibly lead to cold hands, increaseed vibration, generate extra dust/debris. You will need adequate lighting inside the tanks. Its certainly not illegal as such to use 110v equipment inside a confined space, you just have to demonstrate that the equipment is satisfactory and does not increase either the defined risks in the CS Regs or any other risks. You will have to argue it out with the client company, I'm afraid. I wouldn't loose too much sleep over 110v equipment

Posted By Jane Blunt I suggest you consult the HSE on this one. This sounds like an environment where there is an increased risk of electric shock due to accidental contact of parts of the body with a conductor that might be earthed. In this situation even a normal welding set can become lethal. I can recall quite a high profile case of a welder electrocuted while welding inside a tank or pipe. Welding sets designed for use in environments of increased risk of electric shock have the designation 'S' and their no-load voltage is restricted to 113V DC or 68Vpeak/48Vrms AC. Jane

Posted By Daniel R Riley Thanks very much to you all for your quick response. I didn't believe that the use of 110v equipment was illegal but sometimes its difficult to find conclusive evidence. Some of the tanks we work have held flammable products such as petrol; however as i posted they are fully cleaned and declassified prior to us entering, so the worry is purely about electrocution. The use of 24v lighting is a problem to us as some of the tanks are very large and 24v doesn't provide enough light. I think as posted i will need to take this up directly with the client to see if we can change their views on 110v equipment, as our equipment is in very good condition and earthed correctly, the tank is earthed in multiple places, etc. Thanks again for your help, its very much appreciated.