Called to an office block this morning, following a report that some of the staff were occasionally getting electrical shocks and a contractor fitting some new cabling for the computers had got a couple of shocks from the metal frame of the ceiling.
After speaking to the staff it appears there is no patern to these 'shocks' one person gota shock when he touched the metal hand rail of the stairs, another when she touched the printer and so on.
Have checked the Zs to each of the sockets (all are around 0.32) checked all the light fitings and their earths and taken Zs at the lights (max 0.65). Checked continuity of the earths and all are good. The metal grid for the ceiling has continuity to the earths of the lights. I get 0v when testing the metal frame to earth and to neutral.
The only reason I can think for the shocks is a build up of static electricity which then earths when the customers touch a metallic object which is connected to earth. Unless anyone can think of anything else or any other testing I can do
After speaking to the staff it appears there is no patern to these 'shocks' one person gota shock when he touched the metal hand rail of the stairs, another when she touched the printer and so on.
Have checked the Zs to each of the sockets (all are around 0.32) checked all the light fitings and their earths and taken Zs at the lights (max 0.65). Checked continuity of the earths and all are good. The metal grid for the ceiling has continuity to the earths of the lights. I get 0v when testing the metal frame to earth and to neutral.
The only reason I can think for the shocks is a build up of static electricity which then earths when the customers touch a metallic object which is connected to earth. Unless anyone can think of anything else or any other testing I can do
