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Post by soundmanjim on Mar 22, 2005 16:52:46 GMT 1
 Imagine the scene; last fridays gig, first band just about to launch into final number...and all the lights go out. much running around like chicken minus head. into the cellar to discover the main electricity board fuse has blown on the red phase. The fuse itself is red hot! Much panic. Our sparky refuses to touch the fuse. bar manager wants to put a nail in it. fight nearly ensues as our sparks argues with bar manager, (both a bit the worse for wear) another sparks drives to his work and gets another main fuse. meantime i manage to get pa back up by plugging into next phase. second band leave and ask if they will be paid! third band stay on, and after what seemed like forever, 25 mins later power is restored. third band do a blinding set but i only fire up a few lights on stage just in case. What do you people do in this situation? we didnt have a plan, we should have had one. If our red phase fuse is heating up during a gig, can we spread the load accross the phases? bear in mind this is an old building, lots of wire fuses, etc. PA was two qsc 2.5kw amps plus 1 kw of monitoring, 8 par 56's and 8 lf70's for lighting plus assorted gobo jobbies. desk and some other lighting remained on. i am concerned that the electrics are not up to scratch but owners are not forthcoming. what do i do now? your ideas plase!! sorry theres a lot of questions there!
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Post by Gadget on Mar 22, 2005 19:14:11 GMT 1
Hi Jim, "Been there done that" !!! what size of fuse blew ? I try to split loading no matter what the venue , keeping lighting away from the sound. Most places will have a ring main rated at 32a but this can feed x number of sockets. Running lighting is a big drain on power and heavy bass will suck more than usual. I carry a clamp on ampmeter around (as well as multimeter) just to see how much power we pull.
From your list of gear, with everything running out and all lights on you will be pulling @ 20 - 25 amps. But bass will give current peaks which could give a nusance trip .
What I do in this situation if same as you.. find a supply that works, limit the lighting and finish the set in progress.
for the desk to stay on means that the socket it's plugged into is on a different ring.. may be on same phase but check anyway by plugging a light in and pulling the fuses to identify the fuse feeding it. running a mains lead from amprack next to multicore is best way as keeps the desk at the same potential as the amps. The electrics in public buildings should be checked by electrical firms yearly and a sticker placed on the fuse box stating next inspection date.
for a fuse to get "red hot" may mean that the terminals could be oxidized and will give a high resistance to current causing heat and possible fire risk, again this could mean that the fusebox has not been checked for some time.
So first check that there is an inspection sticker on the mains box and take it from there.
hope this helps. Gary
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Post by soundmanjim on Mar 24, 2005 1:22:58 GMT 1
hi gary thanks for that mate.
apparently the last time the fuse went was 5 years ago!
i think there may be some damp in the cellar and this may have contributed. the board are having a butchers. lets hope they dont condemn the whole lot and we have to close!
im off to newquay to do a bit of surfing; i'll check back on this thread on tuesday night for any other helpful info! cheerio!
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Post by IainC on Mar 28, 2005 1:30:48 GMT 1
Im curious as to how you distribute your mains load, lighting should certainly never share the same supply as the PA. As gadget says it is also very important that the system be powered from the same point, apart from the potential risks of cross phasing it is also a good way to introduce earth loops into the system.
how big is the supply? Im guessing it is a 125?
Anyway my advice to you would be to put the lighting and P.A on seperate phases and perhaps replace the fuse board with RCDs, they can be a pain but if there is a problem not only are they safer it is also just the flick of a switch to reset them.
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Post by IainC on Mar 28, 2005 1:33:16 GMT 1
...ooh and shoot your spark for not having spare fuses on site!
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Post by LT on Mar 29, 2005 12:10:43 GMT 1
Mr Iain C is 100% correct, shoot the sparks! no spare fuses, hello! But all systems should now run off of RCDs for that exact reason, so you can flick them back live if they do go! Even the massive festy 100Kva gennys have RCDs. But first of all i do think you should find the rating of your power feed then do the math and find out how much power your PA is drawing! It seems to be a back to basics mission i'm afraid.
The only thing that should ever share phases on a supply is video and sound - so you don't get phasing or earth hum. If you share a phase with lx you will sometimes experiance a hum everytime the lampy pushes a fader, not good! the same with the caterers, everytime the kettle goes on things will blow or make noise!!! But then your sparkie should know all this! Well more than us anyway, we are noise boys not power experts!
LT
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Post by mic mk on Mar 29, 2005 17:14:03 GMT 1
Caterers are the pits with their bloody ovens.
The first thing you notice with an underpowered tent job is a wierd noise coming out of your speakers when the chef turns his 4k oven on.Its time to switch off and have words with the organiser.
Also beware of bouncy castles,tea urns and of course the par cans.Sometimes lighting/power problems don't appear until late in the evening when the old/cheap[njd esp] dimmer packs get way to hot and inefficient.
An occasional check to see who is taking power from your gen/mains source is a very good idea.
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Post by soundmanjim on Mar 29, 2005 19:16:07 GMT 1
ha ha! thanks guys thats very interesting! The place is very old, and the owners of the venue are hard work but i think we have now made headway. our sparks is currently looking at getting the lamps off the pa phase (we had to do it like that before as wiring is severely limited!) so i think all is well now. i will be showing these comments to our crew to digest! thanks guys!  |
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Post by soundmanjim on Apr 5, 2005 13:24:29 GMT 1
;D
problemn solved, we moved the foldback amps back to their normal place in the booth and all is well. Just as a note, our sparks refused (no pun intended) to touch the fuses as they were the Electricity boards main fuses!! I think he could get into bother if he had touched them.
anyhoo, all is well now.
tara
off to fix my avatar!
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Post by pat on Apr 11, 2005 21:37:43 GMT 1
power has always worried me.
all venues i work with my PA never have a large power supply (4kw FOH with 1K foldback).
Whats the best way of wiring it safely?
The only power is from standard 13amp sockets. In the past I have had the amps running off two different sockets on extension leads to spread the load, desk and effects on another socket on the other side of the room.
Lighting has always been the inhouse DIY spots on the ceiling (30w coloured bulb things), but in future gigs we will be renting a lighting rig (16 par56, fogger, lasers and gobo scanner things) off a friend. Where (or how) can I connect it all?!!?!? I didnt even consider where it was going to connect to until I read this!!! HELP.
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Post by soundmanjim on Apr 13, 2005 1:58:46 GMT 1
Se good may come of our misfortune then!!! ;D Glad its making people think!! Dont skimp on cable. get the really heavy duty stuff. Get an electrician to test all your cables for piece of mind. 16 par56 cans will total 4.8KW if they all come on at once, so make sure the lights and controllers are on some nice thick cable (at least 2.5mm). See if the venue will run to fitting in a new mains box with nice new trips to run all your stuff off of. The extention lead to the cooker socket in the kitchen was where we used to plug the lights in years ago!!! Im sure someone else may have more relevant info! Good luck!!  |
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Post by soundmanjim on Apr 13, 2005 2:07:16 GMT 1
In relpy to earlier response;
Sparks has brought his clip meter to the last few gigs, and at one stage we were pulling 50 amps on the red phase, 32 amps on the blue phase and 4 amps on the yellow phase! The fuses arent getting hot although you can detect a very slight warming. DJ may be to blame as he tends to rag the bass on a few of his favourite tunes; we have gaffer taped the bass pot up on the dj desk!!
alls well for now!
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Post by gingerbiscuit69 on Apr 14, 2005 17:43:47 GMT 1
well, sounds good. Venue are tight buggers so wont spend a penny. Theres too much else to be done in the place. On a possitive, I know where the RCD is so I can reset it if it ends in tears.
If i can get my generator repaired (some friends ran it out of oil and knackered it), I can run the lighting off of it (5.5kw continuous). More than enough for the lighting. Just have to hide it away somewhere quiet. Should be running in time for the summer festivals coming up!!
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