Naughty electricity
I'm very good friends with the entertainments manager at a Students' Union. Whilst I was doing my undergrad degree I used to quite often get roped into helping with some of the special projects his technical crew could not cover on their own. This included things like the summer ball, large tours, and in this particular instance - the annual hiring out of our entire PA and lighting grid to a local college for a one day festival.

This festival was always a bit of a bind; we were always shorthanded (usually only about 4 of us) moving a 20 cab Turbosound (and associated amps, desks, multicore etc) alongside a venues worth of lighting, dimmers and cabling in the morning, being set up by 11am, hang around for the day, then strike it at 10pm.

The other problem was a distinct lack of available power. It was an outdoor gig, and we basically had one 32A three phase supply and a bunch of outdoor 13A sockets to play with. This would be fine except we rarely had all the jumpers you'd need, and there's a certain amount of naughtyness about jumping up from low current sockets to larger currents in case you start blowing things up, setting fire to under-rated cables and so forth.

On one memorable occaision we had to Macguyver something together which, 10 years later, remains in my friends office; locked away in a 'break in case of emergencies' case, although he swears he will never be that depserate again; using it only as a cautionary tale for each generation of student crew that come through.

Amps and dimmers all run on 32A supplies. The dimmers (which control all the lights) will easily get up to this draw. For that reason, they were allowed to use the 3 phase supply. Unfortunately, that then left us with the sound kit and no remaining sensible power. Four amplifier racks, each looking for nice big 32A of love. Unless you're driving them particularly hard, however, they don't actually draw too much power. So we set around looking for jumpers so we could feed them from the 13A sockets.

The first work of genius was realising that we had a pair of Y splits which went from a single 63A supply to a pair of 32A sockets. Brilliant. Our only remaining problem now is we needed to get from 13A socket up to two 63A plugs...

The reasoning went something along the lines of one nasty bit of cable is better than two. So as a result we connected our two 63A jumpers to a single length of 63A three phase cable, ran it to the socket then spliced the ends into 13A plugs. Yes ladies and gentlemen, a 3 phase 63A cable with three 13A plugs dangling off the end.

Length? About 20m with strategic sand buckets at either end.
(OP, Fri 21 Aug 2009, 12:30, 8 replies)

I hope you know Ladies and Gentlemen
That I have not a clue about the significance of this post.

As a man I feel impotent. :(
( whenanimalsattackhumans clad in global hypercolour, Fri 21 Aug 2009, 13:10, closed)

Earthed off all three 13As
Or just one of them?

Nicely.
( shadyron, Fri 21 Aug 2009, 13:27, closed)

Shame really
That it didn't all go spectacularly wrong and take out any attending students from said college. The world at large would have benefitted.
(Psymon_Spark Jesus Saves! The rest of you take 4d6 damage, Fri 21 Aug 2009, 13:43, closed)

presumably there is a PAT certificate available for inspection ?

( fudboy high ideals and crazy dreams, Fri 21 Aug 2009, 13:52, closed)

That was possibly the most boring post i have ever read.

(The Kwyjibo A big, dumb, balding North American ape., Fri 21 Aug 2009, 15:15, closed)

Not boring if you understand the subject
Like anything else really. Anyway, plenty more posts to read if you're bored with this one.
( eXOBeX, Fri 21 Aug 2009, 17:16, closed)

I work at a power station
and have seen much, much worse
( parttimedogfish is a Born-Again Reincarnationist, Tue 25 Aug 2009, 1:37, closed)

My only comment
Is that *proper* dimmers use 63A 3ph, and nothing less. Seend that wiring arrangement far too many times though.
(Potty Jag har smör i min rumpspringa, Tue 25 Aug 2009, 15:49, closed)