About Graham Couch Expertise I have over 28 years of experience in aerospace manufacturing and 7 years in Health & Safety, qualifications include IOSH, NEBOSH, COSHH, PUWER, Manual handling DSE and general office and fire safety, I am based in the UK
Experience I have 28 years experience in the aerospace manufacturing industry and 7 years in Health and Safety for an international Aerospace company
Education/Credentials IOSH (managing safely), NEBOSH certificate,(National examination board of occupational safety and health)PUWER,COSHH,Man Handling and DSE Training and experience
Expert: Graham Couch Date: 2/28/2008 Subject: sandblasting static electric shock
Question Dear Mr. Couch, I sandblast crystal bowls in a sandblasting cabinet. When the weather is cold and dry I get static shocks from the cabinet. They don't seem bad enough to be dangerous, but they sure smart. The cabinets metal legs are standing on the concrete floor and I am standing on a rubber mat. I thought that would be enough to ground it but I still get shocked. We were thinking of running a wire from the cabinet to a metal plumbing pipe nearby. Will that work to get it grounded?
Thank you for any information you may have.
Melinda
Answer Hi Melinda the static you are receiving is caused by the friction of the grit on the product and on the insides of the cabinet, the friction creates static build up which when at its peak discharges itself by the route of least resistance, usually you, your body acts like a capacitor and stores the static until you touch an earth, also you may be using a rubber pipe inside the machine to deliver the grit, this insulates you for a while until you touch the metal of the cabinet, then crack you get a shock. It is difficult to find a solution with the information you have provided but I will suggest some controls to try out.
Earthing the cabinet to a copper pipe could work yes, but you are the source of the stored electricity, you could try a static body strap which you attach to your wrist or ankle and then to the machine body this will continuously discharge the static before it builds up to a painful level. Standing on a metal plate wired to the body of the machine could also work
The material of your shoes could insulate you sufficiently to allow static build up also, try thin plastic soled shoes rather than rubber, (bare feet would cure it but exposes you to other hazards).
Any of these should work but if not contact the manufacturer of the machine to see what they suggest. Be sure to have any alterations you make checked by a qualified electrician as well.
I hope this helps, please let me know how you get on.
