ConvergenceTraining wrote:
I know you should de-energize whenever possible, but I understand it's not always possible. Are there certain industries that are known for having to do a lot of live work? Do you know what some of those industries are?
Chemical plants like to incorrectly use the "continuous process" clause in 70E incorrectly. The term is meant to cover large systems where shutting down one component would fall under the greater hazard clause but the component under consideration which would by itself not invoke the greater hazard clause can invoke it indirectly.
Mining companies often have problems with both shock and arc flash incidents. The fatalities for the entire industry are documented in the U.S. There is a large prevalence of both environments where the equipment is frequently subject to mechanical damage, plus moisture and dust, and where medium and higher voltages are in routine use. So you have laborers routinely unplugging large P&L plugs operating at 4160 or 13.5 (or he infamous 995 V) who fail to shut off the disconnects. They can frequently get away with it because by law everything in an underground and/or coal mine must have a ground check circuit in place which shuts off power if they stupidly do so. Plus it is not uncommon to go into panels while live. Sometimes this is legitimate too. Underground mines MUST maintain ventilation and frequently dewatering. There is little leeway on this, but there are ways other than 100% live to achieve it and if pressed, they suddenly find ways to get there.
The whole utility industry frequently works on equipment live. They don't even have the "greater hazard" clause. The rules are written under almost the assumption that all work will be done live. The reason given is reference to an unknown, undocumented "greater hazard" of a customer.
Hospitals are also notorious for this.
Glass plants and coking plants have a problem where shutting down power can be disastrous. They are intentionally designed with redundancy well beyond double ended subs, usually with their own backup generators.
I'd lump steel mills and paper mills into this too but some do and some don't. It all depends on whether as with hospitals, whether production trumps safety or not since there is no absolute dire requirement for 24/7 operation.
An up and coming one is data centers. Telecoms also frequently work on everything live, whether or not it is low voltage.