For Permit to work on electrical systems then BS7671:2008 and EAW act. Got to the hse site and download a free copy of it. Worth a read anyways. try hsg 250 for permit to work also hsg85

PUWER Regulation 19 deals with 'Isolation from sources of energy' and I always include 'Lock-Out Tag-out systems' as a possible control when I'm assessing. The ACoP L22 includes this guidance to reg 19: 273 .... If work on isolated equipment is being done by more than one person, it may be necessary to provide a locking device with multiple locks and keys.... each will have their own lock or key, and all locks have to be taken off before the isolating device can be removed..... keys should not be passed to anyone other than the nominated personnel and should not be interchanged between nominated people.... an example of what I call a Lock-Out Tag-out system

I find the variability in OH&S legislation around the globe interesting indeed. Here in Canada, every jurisdiction requires the employer to provide at no cost to the worker an adequate numbers of locks to those workers who are required to deenergize equipment as parts of their duties. In the context of their intended use, I would be surprised someone could make a case that a lock is just another "tool" like a screwdriver or adjustable wrench is.....

Hi SJP, did you resolve this issue with your employer? paul.skyrme makes a compelling point above. If your boss is trying to off load the purchase of safety equipment onto the employee, I would have grave concerns about the H&S culture in your organisation.