Electrical Safety at events

[Adventure Racer]

Is it voltages or amps that matter?

It's the combination of sufficient quantities of both which is dangerous.

[Barny of Blandford]

Thanks for all the helpfull comments
A few more thoughts now
We earth the generator by connecting to a metre long copper rod that is sunk into the ground - does this give sufficient earth so that both neutral and earth are efficient and an RCD will work - if not what do we have to do.
Secondly what sort of plugs should we be using - computer systems take a lot of plugs and hence there are often several four way gangs - do the same things exist in outdoor plugs
Obviously extension cable connector is inside the tent and all 4 way gangs are also inside - so one option is to get them fitted somehow to table which the operators are using
What else do I need to do?
Thanks in advance for your helpfull comments

[Steve]

[quote="Freefall"]We have used car battery look alikes (leisure batteries for boats and caravans) and an inverter to then power our laptop running SI, the splits printer and an inkjet. Suffient for most of our events.quote]

In this scenario it seems a real shame that it's necessary to convert the nice safe 12VDC supply to 230VAC to supply the laptop, which then converts the 230VAC back to 12VDC to operate!

The ideal solution is a laptop etc that will operate directly from 12VDC, but I don't know if such things exist.

[Steve]

The ideal solution is a laptop etc that will operate directly from 12VDC, but I don't know if such things exist.

Doh! Of course... the power supply for a laptop is external, it's the black box in the middle of the power lead. So in theory it should be possible to supply the laptop directly from a 12V battery, removing the need for an inverter. At worst, a DC-DC converter might be needed.

[FatBoy]

Re Earthing: Pretty well everything you're going to want to run off that generator in a download tent doesn't need an earth anyway, and in fact is a low voltage system run off a power pack (although it's time to throw away that metal angle-poise you use in download...). The RCD will protect mainly against short circuits at the sockets and in the power pack - and it will be quite sensitive to these. Better to let the RCD find out there's a lot of water in that socket than when you come to unplug it. Also a good reason to always switch off the generator before unplugging everything.

Another point about earthing is that putting a rod in the ground doesn't give the same earth as putting another rod in the ground. If you put two rods in 400m apart and measured the potential difference across them it wouldn't be zero. This is why each of our houses has at least one earth rod each, not a common one somewhere down the street, and why all gas and water pipes etc are earth strapped together - trying to get a common earth potential. I don't think in our case you would get enough difference for any earth protection not to work, but worth considering.

Please don't try making a DC-DC converter to run your laptop off a car battery, and definitely don't run it straight off - you will almost certainly get such messy voltage that you will screw something up in the laptop, and batteries can give a hell of a current if you get something short circuit. Some laptop manufacturers if not all sell laptop power packs built exactly for the purpose of running off a car battery (cigarette socket) - let the experts provide all the protective circuitry you need. e.g:

http://accessories.euro.dell.com/sna/productdetail.aspx?c=uk&l=en&cs=ukdhs1&sku=IM-M150270-GB

[roadrunner]

Is it voltages or amps that matter?

The saying used to be "it's the volts that jolts, but the mill[iamp]s that kills". But when you're talking of 240V from a generator, there's plenty of both.