best way to work out where to plug amps and lights etc regarding watts etc

[Pbass1]

Hi, any help much appreciated, new to running a PA and not sure how much you can plug into one socket in terms of watts etc

at the moment there is one rcf active sub 1000w will be 2 eventually

and 2 yamaha dsr 115s rms around 800 900 watts each

also 3 400 rms watt monitors

500 w markbass head

600 w yamaha dxr active speaker as keyboard amp

will also be running 2 Led par bars and a couple of led fx lights

seems like a lot of watts

should you keep lights and amps separate?

should you keep monitors and foh separate?

is there a calculation or rule of thumb ?

confused

Cheers Paul

Edited April 10, 2013 by Pbass1

[BigRedX]

On a UK ring main circuit you can draw just over 3kW from an individual wall socket, and just over 7kW from the ring as a whole.

Remember these things:

1. The calculation needs to be done with input Watts - what the equipment actually consumes - not output Watts which are always lower. These figures are normally on the back of the gear or in the user manuals.
2. There may be other appliances already on the ring main which may reduce the overall power you can draw from it.
3. You will only reach the maximum input wattage (on amps in particular) if you run the gear at maximum volume continually. Most people don't so there will be some capacity to play with. However be aware that some equipment requires a high current draw on power up and could trip the circuit if you are already drawing a lot of power from it. Always turn these items on first.

Edited April 10, 2013 by BigRedX

[TimR]

Few other caveats.

Always fully uncoil extension leads from reels.
Use the shortest extension lead possible.
The more current you draw from a long lead the greater the voltdrop you will get. So theoretically you can get 3kW from a socket but even a 50m
extension lead will dramatically restrict this.

As BigRed says Lights will always draw full current. Sound won't. However, if you have sound to light, more of your lights will come on with your loudest notes. This can play havoc with low voltage and digital effects processors.

Edit: LEDs will be better than old incandescent bulbs.

Edited April 10, 2013 by TimR

[danthevan]

[quote name='TimR' timestamp='1365589125' post='2041365']
Sound won't. However, if you have sound to light, more of your lights will come on with your loudest notes. This can play havoc with low voltage and digital effects processors.

[/quote]

That's interesting. Our lead guitarist has been having some weird issues at gigs lately with his amp just dying or cutting out for no apparent reason. Always ok at rehearsals in various venues, but happens frequently at gigs. He has 2 amps which are identical, one which he has just brought brand new while the older one was in for repair (nothing could be found wrong with it on a 9hr load test) which is doing the same as the old one.
Last venue we played was a pub with 3 double sockets on the wall.............. later traced back to being some 1.5mm flex joining them all together via a junction box tucked behind a radiator, with a 13a plug on the end going into a single socket!
Wonder if this is his problem too?

[Norris]

A thinner flex would be prone to overheat if you try to draw too much current through it - which is why there are different fuse ratings available to protect from risk of fire and/or electrocution. The current you draw depends on the power, but as BigRedX says the equipment power rating (i.e. my "2kW PA") will not be of any help as it also depends on the voltage.

Power = Voltage x Current ...... P = V x I

If you can remember your maths you can re-arrange this to show the current: I = P / V

V = 240 volts in the UK, so divide the actual power rating (in Watts, as printed on the back of your equipment, probably next to the power cable/socket) by 240 to calculate the current draw (in Amps). Or to put it another way, you'll draw 1A for every 240W of mains power.

e.g. a 1000W incandescent lamp would draw 1000/240 = approx 4 amps


I doubt whether drawing too much power would cause issues with your guitarist's amp - the highest rating fuse that fits in a UK plug is 13A and if you draw too much current the fuse would just blow. In my pub covers band we run the PA, guitar amp, bass amp, monitors, (LED) lights and footpedals off a single socket with no problems. This makes it easy to ensure we are all through a circuit breaker and have no earth loops.

I'd look more to overheating as the cause of the cutouts & maybe point a fan at the back of the amp on your next gig as an experiment. As the guitarist's two amps are identical, they probably both suffer the same design flaw

[danthevan]

[quote name='Norris' timestamp='1365597722' post='2041560']
I'd look more to overheating as the cause of the cutouts & maybe point a fan at the back of the amp on your next gig as an experiment. As the guitarist's two amps are identical, they probably both suffer the same design flaw
[/quote]

Doesn't explain why it only happens at gigs though? Always fine at rehearsal and rehearse at virtually the same level as gigging. The only difference is we dont have a dozen can lights strewn around off various 4 way extensions.
Might get him to try the fan in the back, sounds like a simple unobtrusive test, and at the last gig the amp was pretty close to a radiator so you could be onto something!

[flyfisher]

[quote name='danthevan' timestamp='1365589837' post='2041376']
Last venue we played was a pub with 3 double sockets on the wall.............. later traced back to being some 1.5mm flex joining them all together via a junction box tucked behind a radiator, with a 13a plug on the end going into a single socket!
Wonder if this is his problem too?
[/quote]

Long cables and thin wiring will increase resistance and will result in a volts drop to the equipment end of things. Probably not a big deal for things like lights but could certainly upset amps and other equipment, depending on their design.

In general, if the equipment has a 'universal mains input (usually something like 100V - 260V) then it won't be affected, but if it is a fixed 230/240V input then it could be.

However, even if the equipment is not affected, thin/long cables are not a good idea because that volts drop means wasted power within the cables, which means heat. This is why cable reels whould always be fully unwound.

Also, beware that not all extension reels are rated for 13A operation. A 6A extension cable "fixed" with a 13A fuse and not fully unwound is a good recipe for a mass of molten plastic and a blown fuse in the consumer unit!!

[TimR]

[quote name='Norris' timestamp='1365597722' post='2041560']
A thinner flex would be prone to overheat if you try to draw too much current through it - which is why there are different fuse ratings available to protect from risk of fire and/or electrocution. The current you draw depends on the power, but as BigRedX says the equipment power rating (i.e. my "2kW PA") will not be of any help as it also depends on the voltage.

Power = Voltage x Current ...... P = V x I

If you can remember your maths you can re-arrange this to show the current: I = P / V

V = 240 volts in the UK, so divide the actual power rating (in Watts, as printed on the back of your equipment, probably next to the power cable/socket) by 240 to calculate the current draw (in Amps). Or to put it another way, you'll draw 1A for every 240W of mains power.

e.g. a 1000W incandescent lamp would draw 1000/240 = approx 4 amps


I doubt whether drawing too much power would cause issues with your guitarist's amp - the highest rating fuse that fits in a UK plug is 13A and if you draw too much current the fuse would just blow. In my pub covers band we run the PA, guitar amp, bass amp, monitors, (LED) lights and footpedals off a single socket with no problems. This makes it easy to ensure we are all through a circuit breaker and have no earth loops.

I'd look more to overheating as the cause of the cutouts & maybe point a fan at the back of the amp on your next gig as an experiment. As the guitarist's two amps are identical, they probably both suffer the same design flaw
[/quote]

The thinner the wire, the more resistance it has.
The more current you draw, the hotter the wire becomes and the higher it's resistance becomes.
The more resistance the wire has, the more voltage drop you will get.
This is dangerous because fuses can easily carry steady currents of 1.5-2 times their rating for a long time before blowing.

1.5mm2 is not rated at 15amps. The fuse should be 10amp max, possibly 5amps.

Edited April 10, 2013 by TimR

[stingrayPete1977]

Thats not right TimR you can put a 16A MCB to cover a 1.5mm cable, most commercial premises have that arrangement, so a 13A Fuse would be ok.
If the reel is long then you might find a max 10A rating as described above because of the volts drop over that distance but most extension leads rated at 13A are only 1.5mm cable.

[url="http://www.tlc-direct.co.uk/Products/CA1dot5F3.html"]http://www.tlc-direc.../CA1dot5F3.html[/url]

Quite common for 16A applications like caravan leads etc
[url="http://www.industrialextensionleads.co.uk/14m-110v-16a-extension-lead-15mm-arctic-cable-ip67-rated-9620-p.asp"]http://www.industria...ated-9620-p.asp[/url]

It is truly amazing just how much you can get to hold even on a 10Amp fuse on a building site or a marquee gig!

Edited April 10, 2013 by stingrayPete1977

[TimR]

[quote name='stingrayPete1977' timestamp='1365613789' post='2041853']
Thats not right TimR you can put a 16A MCB to cover a 1.5mm cable, most commercial premises have that arrangement, so a 13A Fuse would be ok.
If the reel is long then you might find a max 10A rating as described above because of the volts drop over that distance but most extension leads rated at 13A are only 1.5mm cable.

[url="http://www.tlc-direct.co.uk/Products/CA1dot5F3.html"]http://www.tlc-direc.../CA1dot5F3.html[/url]

Quite common for 16A applications like caravan leads etc
[url="http://www.industrialextensionleads.co.uk/14m-110v-16a-extension-lead-15mm-arctic-cable-ip67-rated-9620-p.asp"]http://www.industria...ated-9620-p.asp[/url]

It is truly amazing just how much you can get to hold even on a 10Amp fuse on a building site or a marquee gig!
[/quote]

I suspect you're right. I've had lots of trouble on marquee gigs where first half has been fine but as soon as the sun goes down and the marquee working lights come on. All the reverb units and digital FX go bonkers and the PA starts distorting.

Flex will have a different rating to fixed installation ring run in singles and MCBs will have different trip curves to fuses.

If odd things happen on certain gigs, only on those type of gigs or at certain venues then it's always going to be the supply.

[stingrayPete1977]

You are right, 1.5 twin and earth is actually higher at 18 amp rating, to be honest if you followed all the cable calcs to the law you house would be full of industrial size cables!

I find its the full valve amps that struggle on anything over one decent ext reel, Its not my forte but I presume them valves like a good supply of juice?

[mushers]

2 double sockets on a ring would be ok i reckon but dont daisy chain those leads you should be fine

[TimR]

[quote name='stingrayPete1977' timestamp='1365615071' post='2041887']
You are right, 1.5 twin and earth is actually higher at 18 amp rating, to be honest if you followed all the cable calcs to the law you house would be full of industrial size cables!

I find its the full valve amps that struggle on anything over one decent ext reel, Its not my forte but I presume them valves like a good supply of juice?
[/quote]

Hmmm. You sidetracked me from the original problem. In a fixed installation you factor in diversity and usually have a fairly fixed load.

The problem with the extension leads having thin cables isn't that they can't carry the current, it's that they have relatively high resistance.

Fine for a single load like a light or lawnmower.

Think about a band situation. Every time you add an amp you are adding a transformer in parallel. This reduces the resistance of the 'load' and makes the resistance of the cable more of a factor.

Once the restance of the load drops to 10x the resistance of the cable 1/10th of your voltage will drop across the cable.

This won't blow your fuse because you're not pulling enough current. Your amp will only be running at 90% voltage though.

[mushers]

ive had a few beers so forgive me if im wrong to question this but transformers reduce the resistance ?

[Gazm]

A couple of times we've had to run a similar amount of kit to the OP from a single 13A socket - surprisingly it worked fine without tripping.
I think the biggest factor is that sound isn't a constant sine RMS and the power delivered averages considerably less than you would imagine IMHO.
Marquees are another story though due to voltage drop on cables, generators with insufficient capacity etc.

[TimR]

[quote name='mushers' timestamp='1365622136' post='2042047']
ive had a few beers so forgive me if im wrong to question this but transformers reduce the resistance ?
[/quote]

You are adding them in parallel.

The resistance on the end of the extension lead reduces everytime you increase the number of amplifiers. In the same way as when you are adding speakers to an amp. BUT worse because the resistances aren't all the same. The total resistance will always be lower than the lowest resistance.

Edited April 10, 2013 by TimR

[Pbass1]

Hi, thanks for all the advice so far, though still a bit confused checked the back of the rcf sub and it says 1100w max

as did the markbass head 600w max

the db technologies monitors were 450 w max each this is the figure given next to the iec connector

then went to look for power consumption of the dsr15 and online they are showing 100w power consumption each

dxr 10 90w

do different manufacturers measure in such different ways or is the 100w power consumption figure of the yamahas a more realistic figure to go by for a high output amp between 800 and a thousand rms, all are digital modern amps so suprised at the different ratings.

and the kam par bars online figure is 50 w power consumtion

cheers Paul

Edited April 11, 2013 by Pbass1

[BigRedX]

What you get out compared with what you put in depends on how efficient the equipment is. Digital stuff is pretty good, normally the consumption is 10-25% more than the output. Valve amps by comparison are very inefficient. Back in the 70s the rule of thumb was that the power consumption of a valve amp was roughly twice it's output rating!

[Pbass1]

[quote name='BigRedX' timestamp='1365680105' post='2042723']
What you get out compared with what you put in depends on how efficient the equipment is. Digital stuff is pretty good, normally the consumption is 10-25% more than the output. Valve amps by comparison are very inefficient. Back in the 70s the rule of thumb was that the power consumption of a valve amp was roughly twice it's output rating!
[/quote]

How are the yamahas showing such a low input of 100w when the output is 900w?

[BigRedX]

[quote name='Pbass1' timestamp='1365681019' post='2042739']
How are the yamahas showing such a low input of 100w when the output is 900w?
[/quote]

Because the figures are wrong. If you could get more power out than you put in you'll have solved the world's energy problems.

[Pbass1]

[quote name='BigRedX' timestamp='1365682151' post='2042762']
Because the figures are wrong. If you could get more power out than you put in you'll have solved the world's energy problems.
[/quote]

I get that, but quite strange for a company like yamaha to make a mistake like that, thats why I asked are they measuring in different ways or a different unrelated factor,
I didnt think theyd gone nuclear or invented perpetual motion lol

also these figures seem to tie in with Gazm experiences

what Im saying is this figure some kind of a typical draw rather than the max quoted by db markbass and rcf are they being belt and braces and yamaha more real world?

[Norris]

Then to complicate things, your equipment won't draw it's full rated power all of the time unless you are driving it flat out. A lot of equipment will draw a lot of power when you switch it on, then settle down to a fraction of its maximum power. However as I said, if you draw too much power you will blow a fuse (assuming the correct one is fitted).

I'd still look to either overheating within the amplifier (a gig will be more hot & humid than a rehearsal - assuming the audience has turned up ), or voltage drops due to long extension cables and/or spur sockets. The thing is it doesn't seem to be affecting any of your other equipment.

I don't think you've mentioned what type of amplifier your guitarist has - is it valve (which might be affected more by under-voltage situations)? If you have a multi-meter you could (CAREFULLY!) check the mains voltage at the problematic venues - try without any equipment plugged in and again with everything plugged in & powered up, and compare.

[danthevan]

[quote name='Norris' timestamp='1365684107' post='2042823']

I don't think you've mentioned what type of amplifier your guitarist has - is it valve (which might be affected more by under-voltage situations)? If you have a multi-meter you could (CAREFULLY!) check the mains voltage at the problematic venues - try without any equipment plugged in and again with everything plugged in & powered up, and compare.
[/quote]

Both fender valve amps. The newer one is (looking at a pic from google) a hot rod, and the older one is it's previous version.

[BigRedX]

[quote name='Pbass1' timestamp='1365683147' post='2042800']
I get that, but quite strange for a company like yamaha to make a mistake like that, thats why I asked are they measuring in different ways or a different unrelated factor,
[/quote]

Yamaha have made far worse and more amusing mistakes in their literature in the past. I'd suspect something as simple as a missing "0" in this case though.

[dmccombe7]

[sup]Do what i did and go LED lights.[/sup]
[sup]15 PARS, 2 smoke machines, lazer, 4 projectors, scanner all running off a 13A socket.[/sup]
[sup]I tested the current load using multimeter current setting in series on full load with both smoke machine heaters on and max current load was between 6 & 7 amps.[/sup]
[sup]Down side is LED lights aren't just as bright as old PARS.[/sup]

[sup]Dave[/sup]