Posted By Robert Randall Here’s one for the “leckie’s” out there I notice that the HSE recommend 12v or 24v ELV lighting when working inside steel tanks (INDG258). Why is 110-volt centre-tapped earth equipment not considered suitable? Is this because there is a greater risk due to the possibility of the cable coming into contact with the steel tank and chafing and thus energising the tank at 110-volts? Don’t be offended but please only answer this question if you definitely know the answer, i.e. you are qualified in the appropriate discipline. Regards, and thanks in advance, Bob R

Posted By Garry Homer Working inside a steel tank is a 'special' location as defined by the wiring regulations. Section 606 in the 16th ed and 706 in the new 17th ed. The concern is that a persons body can be in contact with a large surface of conducting material and there is very little that can be done to avoid it. Therefore the regulations require supplies to hand lamps to be SELV - Separated Extra Low Voltage. Reg 606-04-02 or Reg 706.410.3.10 The definition of Extra Low Voltage within the Regs is; normally not exceeding 50V ac either between conductors or to earth. Clearly the normal centre tapped 110V transformer does not meet this requirement. Hope this clarifies why the HSE give the advice they do. Regards Garry Homer B.Sc. MIEEE and member of NAPIT

Posted By Robert Randall Thanks Gary and Bob et al, that was helpful.