Power at Gigs - Living on the edge!

PermanentWaves

Hi all,

This might be a daft question but then I'm an expert at daft questions.

It occurred to me that our band needs a lot of power outlets. This isn't an issue in our rehearsal rooms as they sensibly have numerous power sockets and each on has a 4 way strip.

I imagine that places that have bands on are also similarly well set up.

However, our main venues are going to be village halls, rugby clubs, etc. Basically any private venue that someone would hire for birthday party, etc.

I imagine we'd find ourselves stuck up one end of the room and maybe only have access to two power outlets from the wall.

The thought of running 4 ways strips into more 4 way strips so that we have enough sockets scares me stiff! At best, I can see it overloading and no noise from the band. At worse, I can see if blowing and taking the electrics at the venue with it!

So, what do you guys do? Or do you all just chance it. Living on the edge so as to speak

Cheers
Mike

spacecadet

If there are more sockets around the room, we have 30m extensions to run round. The more sockets the better. If you don't have a choice, plug in and hope for the best!

David5150

Its a valid question - we have ran our whole band - PA, bass/guitar amps and LED lighting from one socket before but didn't feel overly happy about it. Always keep a couple of long extension leads in the gig bags and take a little plug tester  thing to check the sockets are wired properly

Danny1969

It's not good practice to use a fourway into a fourway etc but it won't do any harm as long as you don't exceed the current capability of any cable. If you have a fourway plugged into a wall socket and then you plug three more into that first fourway .... then the first one has to carry the current for whatever is  plugged into all three as it's in series with them. Pay attention to the rating off the fourway, some are 13 amp but some are only 5 amp. Don't use cheap ones, the internal sprung metal needs to constantly grip the plug and the cheap ones go slack and cause grieve

Don't use reeled cabled rolled up they need to be unwound otherwise they can act as a giant resistor \ inductor when you draw a large current through em

Powerful PA amps , high wattage lights are better straight into their own wall socket

You can calculate what current your gonna draw by looking at the total watts a device uses and applying ohms law to 240 volts. By this I mean the rating written on the back as a 40 watt valve amp uses a lot more than 40 watts due to inefficiency of design for example. 

P = VI where  P is Watts, V is volts and I is current in amps,  so knowing the volts is 240 and the watts are written on the back you can work out the amps drawn quite easily

With today's class D Pa amps and Led lighting the situation is better than it used to be
When I started giging on a bigger scale we couldn't run everything off one mains ring we used to use the cooker ring in a lot of venues

maltingsaudio

Danny again has wisdom, Always carry enough extensions to cover what you might need in worst case scenarios also RCD's on the first thing you plug into the wall after having checked sockets with a socket tester. IF THE SOCKET TESTER SHOWS A FAULT DO NOT USE IT IN ANY CASE. better to pull the gig than suffer the consequences.

vasselmeyer

Wisdom for @Danny1969, a very good summary.

We also play pubs and village halls etc. In one case we had to run the entire band plus PA off one socket. Nervous times. I've also refused to play in places where the sockets were hanging off the wall or wouldn't work with an RCD. In one place the landlord got really shirty and told me how none of the other bands worried about it (more fool them, as far as I was concerned). He got so mouthy when we refused to play and he had a pub full of punters that we just packed up and left and then reported him for a Health & Safety violation the next day. He had to get an electrician in to sort out his shit.

Because of these situations where the quality of the power is unknown I put RCD on the end of everything that plugs into the wall so if there's a dodgy circuit I don't become a conductor between my strings and the mic. Even better might be to think about running modelling or DI boxes into the PA then often all you need is to make sure the PA and whatever lights you are using have enough juice.

stickyfiddle

I've run a band off one double outlet before. You have to do your sums beforehands to make sure you're not frying anything but most music gear doesn't actually need that much power compared to kettles and toasters.

LED lights help too

lloyd

I'm guilty of  using the 4-way and not testing any sockets.....which I know is bad but generally my amp has it's own socket with pedals in another, which isn't too bad, i do keep meaning to buy some surge protector sockets, but haven't as I'm lazy and forgetful.....

Cabicular

I'm a 25 year gigging veteran and things have got a lot better

Having said that there is a good reason I always use wireless with my guitar

hywelg

Make every band member have their own long extension with an RCD. Make sure they only plug into their own extension if at all possible.

Guitarists whould only ever plug into one mains source, so dont plug your amp into one wall socket and your pedal supply into another, recipe for hum!!.

ICBM

What Danny said.

You can run up to 6KW from a single dual-13A wall socket - that's a lot, to exceed that you're going to need a very big professional PA rig and full lighting, especially these days with efficient Class D PA power and LED lighting. A typical backline won't draw more than about 1KW in total - even 100W guitar amps draw under 400W at full tilt, and bass amps are more efficient if solid state, a 300W bass amp may draw up to about 700W.

But it is very important that if that's what you have and you're going to daisy-chain 4-ways, to do it the right way. The best way is to use two really heavy-duty (full 13A-rated) ones plugged into the wall, probably going to opposite sides of the stage, then plug all the others into those, which gives you up to a maximum of eight 4-ways (32 outlets in total), which should be enough for anything, and means that at worst nothing is going through more than two 4-ways. Obviously if you don't need that many outlets you can plug some of the gear directly into the first pair of 4-ways - start with the big stuff. Try not to daisy-chain more than two 4-ways in series, since that's when it becomes likely that you might exceed the current rating of the ones closer to the wall.

In fact, if your power requirements are less than this it is actually *safer* to run everything from one socket like this - because it guarantees that it's all on the same mains circuit, and that the earth wiring is all connected together. The most dangerous situation of all is where you're plugged into more than one wall socket, and one has a good safe earth and the other is faulty - that can lead to *you* completing the current path from live to earth, which in a system without an RCD trip will quite possibly kill you.

Thankfully electrical safety regs are a lot tighter now than they were in the old days, although it still isn't impossible you'll come across somewhere dodgy.

Despite scare stories (including at least one fire safety radio ad I've heard), it is not actually dangerous to run multiple 4-ways and adaptor blocks from the same mains outlet - *provided* each one has the correct fuse value in its plug - the worst that will happen if you overload something is that it will blow a fuse. This is the great brilliance of the UK system where the fuse is in the plug. The only danger really is that it's possible to put a 13A fuse in a 4-way made from much lower-rated cable.

MikkiMcMurderer

I seem to remember that Sound on Sound commonly recommend the "star" method of power distribution from one socket (i.e. one 4 gang into the wall and 4 plugged into it) for home studios as it avoids hum from different ring mains and one 13 amp socket should be plenty for modern studio gear. For live, as long as you're not using old skool parcans you won't draw anywhere near 13 amps. I bought one of those current draw meters and measured the whole band and PA and lights for our normal set up (2 QSC subs and tops, loads of LED lights and usual 4 piece back line) and it didn't go over 4 amps. 

ICBM

MikkiMcMurderer said:

I seem to remember that Sound on Sound commonly recommend the "star" method of power distribution from one socket (i.e. one 4 gang into the wall and 4 plugged into it) for home studios as it avoids hum from different ring mains

Yes, that's another good reason.

MikkiMcMurderer said:

I bought one of those current draw meters and measured the whole band and PA and lights for our normal set up (2 QSC subs and tops, loads of LED lights and usual 4 piece back line) and it didn't go over 4 amps. 

Was that at idle, or gig volume? There can be quite a difference with modern PA amps in particular, and some bass amps. Valve guitar amps less so, since they're inefficient at idle. Under 1KW seems a bit light for that lot, although if you play fairly quietly then probably not.

MikkiMcMurderer

Was that at idle, or gig volume? There can be quite a difference with modern PA amps in particular, and some bass amps. Valve guitar amps less so, since they're inefficient at idle. Under 1KW seems a bit light for that lot, although if you play fairly quietly then probably not.[/quote]

D'oh, I didn't think about that! I'll have to redo the test! It's going to be a bit hard looking at it on the wall behind the drummer while playing!

ESBlonde

I had an outdoor gig running various bands backline at full bore and my 6Kw PA and 2.5Kw monitor rig (daylight so no lighting) and old school power supplies not digital on the amplifiers. The genny was well over spec'd and the 63A single phase feed we had showed an 8Amp current draw for the lot. Now I expect the analogue meter couldn't properly respond to the short term nuances but it was flickering to the kick drum and I expect gave a decent representation of the RMS draw in use. I have run the whole rig from a single 13A wall socket many a time and the plug/cable doesn't even get warm so in practical terms that's a decent guide to what you can do. Warning always power up the amps last (start at the mic and go down the audio chain to turn things on) and one at a time with a few seconds between to allow for current in rush to the soothing caps.
Lighting is a whole other issue and old incandescent lamps take no prisoners as far as current draw is concerned.

ICBM

ESBlonde said:

I had an outdoor gig running various bands backline at full bore and my 6Kw PA and 2.5Kw monitor rig (daylight so no lighting) and old school power supplies not digital on the amplifiers. The genny was well over spec'd and the 63A single phase feed we had showed an 8Amp current draw for the lot. Now I expect the analogue meter couldn't properly respond to the short term nuances but it was flickering to the kick drum and I expect gave a decent representation of the RMS draw in use. I have run the whole rig from a single 13A wall socket many a time and the plug/cable doesn't even get warm so in practical terms that's a decent guide to what you can do.

It's probably worth mentioning that for live mixed music, the transients are probably at least 10dB above the average level and so for a truly clean sound on the PA, the average power output will be no higher than 1/10th of the system capability, ie about 600W for a 6KW system. Even if it's Class AB so it could be as low as 50% efficient, that means the PA amps will be drawing an average of about 1200W, or 5A - given that the filter caps should deal with the transients and although the average will fluctuate a bit it won't go anywhere near the instantaneous peak power output - so an 8A draw for everything sounds in line with what I would expect and there probably isn't much metering error.