Outdoor entertainment licence condition

30 MA @ 230 V = 7 GW. you would need several interconnectors for that.

Why would metalwork, especially those items having no electrical equipment attached to it (eg tent pegs), need RCD protection? And how could that be achieved?

I suspect that it's related to some incident where someone got electrocuted by live metalwork that hadn't been earthed/bonded/whatever.  The person who wrote that probably knows nothing of BS7909 or BS7671.

A short length of anything less than about 400mm2 will disconnect the 30MA within the required 0,4 seconds as will the clamps connecting  the scaffolding itsellf   However, one suspects a sticky shift key as there are about 3 or 4 orders of magnitude between that and the PSSC of any normal power supply and more like 5 for supplies on camp sites festivals and so on.

Mike.

lyledunn said:

Quite why the condition did not simply refer to the need for compliance with BS7909 or perhaps section 740 of 7671

I think there are at least two reasons:

1. BS 7671, since the introduction of the 17th Ed in 2008, doesn't really address extraneous-conductive-parts outside buildings, only requiring protective equipotential bonding in each building (see Regulation 411.3.1.2). This is not universally accepted, and the water industry specifications (WIMES) has a different view, for some very good reasons; having said that, BS 7671 is a "minimum standard" and not a "specification" ...
   
   
   
2. Regulation 411.3.1.1 might apply if the stated 'conductive parts' are connected, fortuitously or otherwise, to exposed-conductive-parts connected to different earthing systems ... BUT you can't just bond these, or connect them through the conducive parts as stated. Ignoring PME issues and diverted neutral currents, see Regulation 542.1.3.3.

lyledunn said:

Quite why the condition did not simply refer to the need for compliance with BS7909 or perhaps section 740 of 7671 instead of a singling out one issue

Because that would require the enforcing body to check compliance to the whole standard - not good for anyone from either side. (In terms of effort required relative to the actual risk.) I'd agree with Simon, it'll be due to a specific concern, so it makes sense to define what is specifically required. I suspect someone who knew what they were doing did advise the words (although they may have got mis-translated along the way), including carefully including "sufficiently" and "adequate" - i.e. just one step away from saying what they really meant which was "just get someone who knows what they are doing to give it a look over before you stand children on there in the rain"!

And yes, having been involved in many outdoor charity etc music events set up by volunteers in one of the rainier parts of the country I'd say that is a sensible part of an outdoor entertainment licence as a bare minimum...

It's a huge challenge in any sort of risk assessment that's going to be applied to a wide range of activities, do you go so precise that people stop thinking and you risk massively over- or under-specifying what's needed, or do you go so "high level" that you start huge debates about what's actually needed. No easy answer to that one. For example, they could have said here "the system must be checked for bonding by a qualified (whatever that means) electrician". Sensible for a stage arrangement to carry 100 people and a many kW PW system and lighting rig, not appropriate for a few scaffold bars around hay bales at a village fete.  

There is also the risk that the organisers of the event, don't have either standard to hand and that lots of it does not really apply - certainly at the "hay bale theatre" end of the spectrum alluded to above. 

Actually there is always  a 'how much actually applies here ? ' problem. 
For example I have taken part in earnest but quite comical debates about the installation of battery back-up emergency lights in a marquee in the past.  The  local authority inspectors were so stuck in the mindset of fixed buildings, that the idea of a structure where at a push, and actually not that much of a push, the whole side becomes an emergency exit was a problem. Initially  they could not really see in the standard rules what was needed for a disco in a big tent in an even bigger field, and  that 2 hour backed up light every metre along the edge because that was all 'exit' was probably overkill.  We settled on a couple of frog eyes lamps and labelling a couple of panels as preferred exits in the end but it was quite amusing to see the horror at some original thought being needed. 

Mike.

A tent can go up in flames pretty quickly.

My experience in RN was that fire hoses were faked out (but not charged) on the lawn whenever a marquee was put up.

indeed, and that's sort of my point,  it's just nothing at all like a 'real building' and those of us that have a lot to do with them plan accordingly.

Requesting a test for a two hour illuminated exit time like its a high street cinema with entrance corridors and doorways or something is cobblers.

Even talking about  2 minutes to get everyone out might not really be fast enough to be safe if  something really takes off.  It's also why gas bottles for cooking are left outside and we grumble about big lithium battery packs.

Mike.