From Electromagnetic Field



From latest meeting

  • need to check regulatory requirements (for self-made boxes)
  • check height of bridge (9'9) against height of delivery truck

  • 150w per person for camping?
  • research about other load

Mains supply

  • who pays the bill
  • who supplys them, meter needs changing
  • can we replace the cabinet
  • current for gauging station


Before we start designing a network we need to work out the maximum load levels. We have created a spreadsheet to try and work out what sort of power supply we will need. Please add your thoughts to it: Google spreadsheet containing load estimates

If power is to be run to every tent, how much should be offered? Obviously 3kw heaters and kettles are out unless the budget is massive, but are we talking 50w or 1000w? Fifty should run one laptop (30w) and phone charger (1w) and small energy saving bulb (10w). Obviously some people will want to being 40A argon gas lasers or soldering irons, maybe we need to put power into chargeable bands. Would it be reasonable to ask all people who want power to there tent to pay a supplement for it?

150W was the rough figure that came up early on in the planning.

Will there be any big single power sources other than the central comm's/site office? Live music stages etc?

Mains Supply

Mains power

Running through Pineham is a 11kV overhead line. In the middle of the site is a pole mounted transformer, this is rated at 25kVA. The transformer does feed the gauging station on the Ouzel located next to the motorway bridge. The fuse on the pole should be 100A. The amount of current we can pull depends on what the gauging station is pulling. So 60/80A hopefully can be achieved.

The supply is terminated into a large rusty meter cabinet with no door. It would be wise to replace this with something a bit more secure. The meter seams to be intact. All of the wiring past the meter has been removed, whether this was due to theft or previous owners. To remove the wiring it looks like they removed the cut-out fuse so it could be striped down safely. It is more than lightly that the cut-out is still live but needs to be tested.

This supply will be really useful for the camp. Generators will only have to be run for the days when the camp is being run. One downside is that the installation will need testing by a electrician. It would be good if we could have some ceeform plugs connected.

Replacing the transformer with a larger one might be a option.

Close up pics of the pole and meter:

[1] [2] [3] [4]

MKPT say power supply on site is max 200A but predates their ownership which is 1994.

  • Series 7 single phase cutout is max 100A, Transformer is only 25kVA.
  • Meter is dated 1999, also is digital. Series 7 cutout, brown phase insulation, blue meter tail would hit that it is fairly new.

Generator Supply

The rest of the power comes from super silenced diesel generators spread around the site. Generators normally have enough fuel for the entire event with plenty spare as the tanks are designed for much longer running.

  • we have our generators filled up every day at work, Benny

Generators and fuel for one weekend are cheap compared to other costs, especially when they are sized most cost efficiently (the cost/power graph is not a straight or even curved line).


Although running power to every tent is un-common, camping festivals are normally obliged to run lighting to all public areas which can often work out as a decent number of watts per tent anyway.

Distribution is expensive, both in metres and breakout boards. Planning is key, balancing cable distance against using more generators. Sometimes it's even cheaper to rent a larger generator then a smaller one and an additional breakout board just to get enough sockets. Consider crowd-sourcing infrastructure, many potential attendee's might have a few hundred metres of event wiring sitting around.

Although time consuming, making the smaller cables (like Y splitters) can save a lot of money, purely because they are premium items. If we are able to find a electrician that can test it may be cost effective to make the final distribution units and possible the central distribution units. We might be able to get the items needed at a reduced price by using sponsorship from a electrical suppliers.

Tom Allen from Reading Hack Space has volunteered to look into this once requirements are more clear, he has previous outdoor event experiance -

The standard for temporary distribution connectors is powerlock and ceeform.

Powerlock connectors are used for high current. They connectors and cables are run in singles allowing them to be much more manageable.

Ceeform connectors are used for lower current connections. The common colours are yellow (110v splitΦ), blue (230v 1Φ), red (400v 3Φ). The standard current rating are 16A, 32A, 63A and 125A.

Final Distribution Unit -> Tent

Would it be reasonable to ask all people who want power to bring there own extension cord of at least 10m?

If a low per person allowance is given a lot of people can be fed of one 16A cable.

Asking everyone that would like power to bring a cable terminated with a ceeform connector is not going to be possible, this would also cost more as ceeform sockets are expensive. The solution would be to do like most other camps and have some sort of weatherproofing over standard domestic connectors. Portaloos are most commonly used for this, hire is quite costly for them. Using a enclosure would be a much better solution. Meter boxes are relativity cheap and provide a reasonable amount of room. Surface mount boxes would be better as they are completely enclosed. Finding a sponsor for these would save us a fair sum.

The box could ether have a trailing 16a socket or a fixed one on the side of the box. Some mcbs could be added if even more load control was wanted. This could then feed a couple of sets of extension gangs. Where the cables enter the box some sort of sealing device is needed to keep the box sealed.

Networking equipment could also make use of this space.

  • what do the regs say about running standard flex over the ground outdoors?
  • foam vs putty for sealing
  • Going to make a mockup, Benny.

Whenever we supply a power connection we need to ensure both physical (IP65? 66? 67?) aspects and electrical (shorts, earth-leakage) issues. Where this connection is to a major location - marquee, etc - this is nice and straightforward and is clearly something we'd expect to cover the cost of. But I'm not sure we should have the unlimited liability for 'per tent'-type connections. Each tent (which wants a connection) will require a physical connect. That connect needs to be covered by its own RCD/RCBO imho otherwise one bad cable or socket which gets into some mud will 'blow' the circuits feeding multiple users, with concomitant dangers. Also in this area, I'm not sure it is unreasonable to require people bring their own ceeform breakout cable: a simple 16A single-phase plug and socket can be bought all over the country in a B&Q or Screwfix etc if they don't have one - and if they don't want to make their own we can sell them premade onsite. Otherwise we could be looking at covering the cost of more than 250 individual breakouts with RCDs which would be really expensive; basically it comes down to whether the per-unit cost is ours or theirs. I'd be happy to co-ordinate this.

  • As long as the sockets are adequately protected from the weather by other means then I don't see why it's necessary to demand people use an IEC 309 connector. As for RCDs, it is our responsibility to provide residual current protection on these circuits. Providing one RCD per hookup is impractical, so this will likely have to be one per cabinet. (16A RCBOs are ~10-20x the price of 16A MCBs.) I don't see what risk there is in having a group of tent circuits trip because of one fault, and I also don't see how we can avoid this situation happening as we'd have to provide 30mA residual current protection at the handoff point. Russ 16:49, 18 April 2012 (UTC)


BS7909 Code of practice for temporary electrical systems for entertainment and related purposes

  • Cables for indoor, BS6500 PVC or rubber insulated.
  • Cables for outdoors and in general, BS7919 rubber.
  • Thermoplastic cables (artic blue) are not suitable for outdoor use.
  • BS EN 60309 for connectors (ceeform).
  • BS1363A (uk sockets) should not be used outdoors.
  • BS7430:1998 Earting for mobile generators
  • BS EN 61439 for indoor equipment used outdoors.
  • BS EN 60529:1992+A2 IP Codes.
  • Final Circuits should be protected by an RCD with a rated residual operating current <= 30mA. No more that six final circuits should be protected by a single rcd. Emergency lighting shouldnt share etc..
  • IP44 - Equipment located outdoors
  • IPX8 - Equipment in contact with water
  • All equipemt should be inspected and tested before delievery to site, certificate should be provied.
  • Earth electorde, polarity, phase rotation, earth loop inpedance, rcds, NE indication should all be checked on site.
  • Plugs and socket in areas where the public are permitted should be secured against interference.
  • Tests before, contunuity, insulation reistance, polarity, rcds, functional?

BS5266 Emergency lighting. Code of practice for the emergency escape lighting of premises? BS EN 12193 BS EN 50172 HSG 195 PAS 51

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