Electrical Safety at events

[Barny of Blandford]

I am having my ears 'bent' a bit about electrical safety of SI equipment at events.
We use a generator for our SI obviously producing 240 volts and off this everything works using initially an extension lead and then onto 4-way gang sockets
Everything is what I would call indoor equipment and operates in a club tent in rain or sunshine
Now if I was in the building trade - obviously a dangerous outdoor environment - I would have to operate at 110volts for everything
Also if I work in my garden I have a circuit breaker set
Also outdoor electrics have different plugs and so on as we often see at camp sites when caravans and campervans plug in
What do other clubs do to make sure they are not likely to electrocute their SI or EMIT team or am I worrying too much

[mharky]

you're worrying too much

[FatBoy]

Just pretend you're French and then levels of electrical safety are much lower...but seriously:

One thing is to use a UPS (as shown in previous thread recently) - this will act as a circuit breaker if overloaded (e.g. due to short circuit because too much water), not to mention the benefits the other way of surge protection and some residual power when the generator runs out of fuel.

Building sites working at 110V isn't necessarily a safety thing, more to do with equipment from the US. If it was purely a safety thing then it would almost certainly by 12V. Also half the building regs to do with electrics aren't specified by engineers but by pen pushers and if you reverted them to first principles you can prove they are totally over the top.

The plugs for outdoor use are just designed to be waterproof. If there's a connection you're not happy with just wrap it a carrier bag and tape up. I use a plastic crate under the desk to put connections in when on grass.

Above all though - make sure your tent is waterproof!

[Kitch]

rubber boots ?

[Knee Deep Mud!]

A few (possibly not 100% accurate as yet) words from someone with a boss who has decided they should start cross skilling into electrical engineering....

Building sites working at 110V isn't necessarily a safety thing, more to do with equipment from the US.

Not true. 110V supplies for use on construction sites are "Reduced Low Voltage" ie they use a centre tapped transformer which actually gives ±55V. This is different to the US domestic supplies which use 0-110V.

For outdoor portable equipment installations, the British Standards allow

230V supplies with 30mA RCD protection
Safety Extra Low Voltage supplies ( <50V )
Reduced Low Voltage supplies (as described above)


Outdoor plugs and sockets should probably be to BS EN 60309 as these are designed to be suitable for outdoor use. These are round plugs and sockets, yellow for 110V and blue for 240V.


On a legal note. If (as quite a few clubs do), you get someone to do the onsite IT on a paid professional basis, then the "Electricity At Work Regulations" would apply to them. These state

Electrical equipment which may reasonably foreseeably be exposed to the effects of the weather, natural hazards, temperature or pressure; shall be of such construction or as necessary protected as to prevent, so far as is reasonably practicable, danger arising from such exposure.

. Anyone not supplying electrical equipment / plugs / sockets etc suitable for safe use outdoors (and I'd guess that normal indoor domestic equipment would not be deemed suitable) would probably be deemed in breach of this if there was an accident. I'm not sure whether an event organiser / organising club with people 'working' for them on a voluntary basis would be classed as an employer under the regulations and thus be liable in the event of an accident. Health and Safety law usually takes the broadest definition of the words used....

[FatBoy]

I am quite prepared to be corrected on why it's 110V as I got told that by a builder rather than one of my lecturers, although you wonder where they got the idea for that figure from. I am confused though as to how 110V is 0-110V. Are you saying US stuff isn't earthed the same as UK stuff i.e. to the neutral with line being a sine wave peaking circa ±300V? US stuff is quoted as RMS same as ours so probably peaking at about 150V. Just curious as to what the difference is not picking fault. Is it just the figure of 110V for building kit is 110V max difference in voltage? Is it still a sine wave - presumably yes as its come from a transformer?

or as necessary protected

This is the important clause. If you leave standard domestic sockets in long wet grass and then when you pick them up they give you a shock - well you had it coming! If you keep all sockets off the ground in a covered area then that's "necessary protected". The cables aren't anything special - you only need to go to armoured cables when permanently burying them.

Some sort of RCD device is sensible though folks - could be a fault nothing to do with the water that causes a shock.

[Adventure Racer]

I think the point is that instead of a US type supply which has neutral at earth potential and a live with ±150V peaks, you have both neutral and live as sine waves with ±75V peaks relative to earth, but 180 degrees out of phase with each other, such that live is still ±150V p2p relative to neutral. However now somebody getting a shock from live to earth now only sees half the voltage (still enough to kill, so the same precautions apply, but presumably safer than normal UK mains).

[Steve]

why do builders use a 1:1 transformer between the power supply and their gear?

Probably because they can prevent a high current flowing in the event of a short circuit.

[The Cumbrian]

55v-0v-55v still supplies a potential difference of 110v between the live and 'neutral' conductors but has a maximum potential of 55v between earth and either conductor, therefore an unfortunate earthed operator coming in to contact with a phase conductor should not suffer a fatal shock given physiological and environmental norms. Key points are use of RCD protection and suitable IP (ingress protection) rated plugs and sockets BS60309 as stated previously. There is interestingly enough a british standard on the earthing of mobile generators (mostly for the entertainment industry) but potentially still relevant here, if you placed your generator on an insulating surface you may not provide a sufficient earth to ensure protective devices operate, worth considering an earth probe to prevent this problem

[FromTheGrassyKnoll]

On a legal note. If (as quite a few clubs do), you get someone to do the onsite IT on a paid professional basis, then the "Electricity At Work Regulations" would apply to them.

That's interesting. Does that also mean that anyone being paid to IT has to have insurance?

[stodge]

Insurance - depends if you intend on getting sued.

Its one of the reasons I have always done my SI work via Sportident UK rather than direct.

We did have problems at the World Cup where a dodgy 2 pin euro plug on the IOF finish bouncy castle kept tripping out the site electrics. We ended up running it off of its own genny.

I am always very careful that all standard 3 pin plugs are protected ( bagged and taped outside, up off the floor or on plastic inside tents).
If you go for those poh Blue connectors however you are always going to end up breaking out into 3 pin plugs eventually.

Condensation and Dew are the worst enemies though. They creep up unseen on early cold mornings

[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.

The fact is I messed up on the Wallington event and couldn't produce splits on the day was entirely my fault and of course the battery lasted just fine for just the PC!

I guess this system is probably safe(r) than a generator but I never understood electricity anyway.

[Adventure Racer]

I guess this system is probably safe(r) than a generator but I never understood electricity anyway.

Only because it's easier to keep everything in the dry - you've still got the same voltages floating around.

[Freefall]

Is it voltages or amps that matter?

[Knee Deep Mud!]

Done a bit more digging on the subject today. There does seem to be some discussion on the most appropriate way to do things, but the general consensus of opinion was:

Most of the small portable generators of the type probably used by us are designed not to be earthed and to have a floating output i.e. the neutral is not tied to earth, and you don't have to install an earth rod.

Given the floating output, ideally you should only use double isolated equipment with this.

RCDs do not work properly if the generator neutral and earth are not connected, so don't think you are necessarily protected if you use an RCD with a generator.

Standard three pin plugs are not designed for outdoor use. Whilst you probably will get away with using them 99% of the time, you are leaving yourself open to someone getting an electric shock. 1 fatality is one too many...

Trailing leads used in the great outdoors are much more likely to get damaged and cause a hazard. Look very carefully about where you put them, and protect them from damage. Check them for damage every time you use them.

Fence the area of the generator and cables off so that passers by are less likely to come into contact with anything dangerous.

The electricty at work regs only legally cover companies and self employed people doing paid work. However, you would probably not have a leg to stand on if you killed someone having not used appropriate equipment.

I can tell you from personal experience that connecting yourself to 230V is NOT a pleasant experience. I was lucky. The RCD tripped the supply and the muscle spasm caused by the shock threw me (rather violently) clear of the live wire.