[quote name='spacey' timestamp='1369144227' post='2085379']
Circuit breakers wont help.
The stage needs it's own earthing point as close to the stage as humanly possible.
The Rule of thumb is Every 10 meters of wire away from the earthing point and the risk of electrocution trebles.
If the earthing point is at the other end of the lead which is 50+ meters away and round the pubs mains board to the cold water pipe.
You are as good as dead if any type of rain or short causes problems
[b]Any rcd you use can only measure leakage to a bonded earth point so wont trip if the path is via you direct to earth.[/b]
A moderately competent electrician can install an earth point at the stage rigged in to the power supply stage end , or use a generator that is earthed.
If the only source is a very long extension lead with the earthing point at the other end then if there is any, even remote chance of damp or rain I would suggest you do not play.
These things do tend to be make do and hope for the best.
Fatalities are not uncommon when no direct earthing point exists, electricity will take the shortest route to earth and if that is via you as opposed to down the other end of a long extension then it will, it is physics and many a person has won a darwin award from 240v 30 amp ring mains.
If it is not a generator installed by a compliant person I would insist on an electrician certifying the power supply .
You dont get a second chance with this sh*t !
[/quote]
This is totally false, I dont want to get into another basschat electrical debate but its not true at all, any leakage (probably 30mA in this case) anywhere other than back through the RCD unit will result in a trip and should be within 200ms but will normally be less than that, worst I have seen was about 57ms. Unless you know what you are doing adding earth stakes etc can make things worse, even a poor TNC-S supply with up to 3 extension reels will give a few Ohms on an earth loop test, 50-100 maybe worst case with enough voltage left to actually power anything which is very poor really, yet a decent stake would be 200+ at best and more like 500+ in a field miles from anywhere