Have been asked to perhaps pin a electrical guide on "Electrical supplies/installations" for a Marquee disco/band etc

I'll try and cover everything from what I know, and what i've experienced as a sparky.
The information following is a General guide, and the individual should contact the NICEIC or ECA for futher information if the occasion should arise where he/she is unsure what to do or a potential dangerous installation is noted?

We all gig at time to time in a marquee. If you are gigging in a marquee in the future you should be asking the questions below to the person booking the disco (client) or in the second place, the marquee operator/installer (competent person who installed the power facility)

The responsibility of the incoming power for the marquee lies with the person who installed the supply!!
The power supply should be installed and tested to electrical safety ""BS7671 electrical regulations""
The power supply installed into the marquee should be done by a qualified person or a competent person who is able to verify and certify that the tempory installation is safe and comlpies with BS7671 and the electricity at work act

please read the following guidence off the internet on marquee supplies.....

ELECTRICITY INSTALLATIONS IN MARQUEE'S
All temporary low voltage systems (415V or less) on the site will be subject to the “Electricity at Work Regulations 1989” .
All electrical installations should be carried out by a competent electrician familiar with the requirements of the above legislation and should operate to the standards recommended by the Institute of Electrical Engineers. Anyone who provides electrical apparatus for their own or anyone else’s demonstration etc. Should before it is connected to the electrical supply, arrange for its testing by a competent electrician and documentation should show the date of the test and the name of the person carrying out the test. All equipment should be connected to the supply through a residual current device (RCD) and all cables and connections where not protected by a weather proof structure shall be of such construction or as necessary protected to prevent, so far as is reasonably practicable, danger arising from such exposure. Socket outlets should not be over loaded, extension leads should not be used indiscriminately. All mains connected portable and transportable electrical equipment should be installed and used in accordance with HSE Guidance note PM32 “safe use of portable electrical apparatus”. All temporary installations must be safely disconnected and removed from the site after the event. .

more info can be obtained from this web site
http://www.iee.org/Publish/WireRegs/Wiring...nt_purposes.pdf



Questions to ask if the supply is already available when you turn up......



what is the voltage and what is the power current/load available to you?

Is the electrical supply run off mains supply or generator supply

Has the electrical supply been installed and certified as stated above


You do not need to get involved in running power into the marquee. This should be done already for you.
Its not the DJ's Job to rig up power to the marquee. If you do this, your putting yourself at risk from prosecution if something goes wrong, or somebody gets hurt from your actions.
Stick to what you do best...DJ! IF You cannot certify the power supply and therefore should not be doing it!

ok, so you turn up and there is no electricty to the marquee!

What can you do

Run a couple of extention leads from the house to the tent? I suppose you've got no choice really. But try to get the customer to do this for you if you can? (takeds the onus off you) This isnt really deemed as "Marquee electrical installation" its more deemed as a "portable power lead" so BS7671 does not apply in this case. But the electrical leads should still be installed with safety in mind.

As a minimum the extention leads should be PVC or rubber sheathed. Should be able to carry 500v, should be PAT tested regulary and inspected regulary.
The extention lead supplies into the marquee "MUST" be attached at source to an RCD (Residual Current Device)

RCD devce should be 30 milliamp tripping

This means that if the RCD unit "sees" more than 30milliamps of leakage from live or neutral conductors.....it will trip! this actually equates to 50v (meaning that if an RCD is used, no more than 50v can flow to earth or ground before tripping the circuit)
50v has been designed as human "touch voltage" hence why RCD's are set at 30milliamps for this purpose.

Anyway moving on.....general common sense should prevail. The lead cant be installed so it "hangs someone" when they walk past. reasonable steps should be taken to install the leads with safety in mind, tripping hazards etc. This part is down to you.....if your leads from 13amp socket outlets are strung around the marquee, someone gets hurt.....get your public liability docs out!!

so in a nutshell, tempory feeds into a narquee thats bigger than 13amp (taken off a distribution board and not plugged in) should be done by a competent person who can certify the work before use

Extention leads should be safely insalled powered from 13amp socket outlets at the hose, but through RCD device at source...(not at the cd player end!!)

all extention reels shold be fully unwound to counteract the coil effect (cable creating eddie currents and heating up)

All extention cables should be large enough to cope with your demand and fuse correctly at the source plug.

ie a 13amp lead should be 1.5mm flex and fused at 13amps

1.0 cable extention may be fused at 10amps at the plug

Generator supplies

Do not get involved in the installation of a genny. Let the marquee people or sparky do this. You just want a couple of 13amp supplies at the end of the cable!
As long as your stuff is ok, tested (PAT) and you use RCD's.....and install your stuff out of reach etc....then your ok!

Genny voltage must be 230v +/- 10volts max. Your equipment should be ok with this fluctuation.
Again, check with the installer of the machine and look at the certificate (your right to do this before plugging in)

supply frequincy 50 hz no question/no butts!

anything else please ask away

cheers Jeff


regards Jeff

This thread should be stickied, good well informed information.

Oh and this Eddie is not keen on currents, think it's the other eddy

Nice one Jeff.

To echo what he's written, don't ever be dragged into helping with the power supply 'as a favour to the client', no matter how helpful you may be feeling, or how late things are running. It isn't your responsibility, and people can die if you get it wrong.

Good article. Excellent advice.

Just read it back loads of spelling mistakes....thats coz i cant type properlyyyyyyvcbiruv

eddy not eddie

marquee nor narquee

etc etc

just another note to work out your demand required for your gigs

add up the wattages from your equipment...
Lights first...

(ie) datamoon 250watt x 2
acme icolour 500watt x 1
acme moving heads 250watt x 2
smoke machine 700watt x 1

cd players, amps, mp3 player, laptop, bla bla bla.....lets say 500watts for arguements sake

All ads up to errrrrrrrrrrrr 2700 watts

ok now take this wattage total and divide it by 230V = 11.73 amps required to run this stuff!

(A general guide is 4.2 amps per 1000 watts of equipment)

But remember if your extention leads are very long....you will have a volt drop, so a 50 meter lead would be more like 215V not 230V..........

This now makes the equation different....2700 watts divided by 215v = 12.55 amps

So as you can see, the longer your leads are, the bigger the volt drop will be, and therefore the amps required to run your set up will be higher.

Use your head, dont run 12 amps continuously through a 1.5 mm cable, it will get hot after a short time and possibly burn out at the weakest point (plug or terminal somewhere)

Run 2 leads and splt the load up a bit

When doing your calculations on equipment "draw" from the power....always add a few amps to be on the safe side

So if tou get asked "how much power you need mate" for the above example say......16 please mate or even 20! let them work a bit to fail safe you!!

try to keep "sound" on one and "lights" on another (depending on the above calcs)...less likely for the lights to upset your sound system when buzzing about doing their thing

jeff

Thanks Jeff! BRILLIANT!

Nice post Jeff

as a fellow "qualified" sparks this stuff gives me nightmares, definately a case sometimes of ignorance is bliss.

another add on to post (sorry)

Just about RCD units and the actual sockets your running from at the house end..

This applies to all jobs, not just marquee jobs

Who knows whether the 13amp socket in the customers house/venue is earthed?? You cant tell my looking at it, you cant tell by taking the cover off (may be connected at the socket but absent at the fuseboard?/)

A martindale tester would help, but sometimes not reliable

So you connect up to a double socket or whatever....not knowing that the earth terminal either inside the socket or at the fuseboard is broken/not installed

Therefore your running your stuff on an "un-earthed" system.........mmmmmm....what now??

This will cause an electrical shock to occur on the metal parts of your installation IF a fault developes whilst your gigging.

Easy Answer!!
Just use the RCD or RCD's in your bag. The RCD will work regardless of an earth connection or not. Keeps your stuff safe and more importantly people safe. It will trip if an "imbalance occurs" either from live or neutral connections/wires

Another good reason to use an RCD on your system

remeber though, 30milliamps trip on an RCD is quite low, they can trip easily with badly maintained equipment.

Another reason to keep your stuff PAT tested! Apart from the safety issue, you have the issue of possibly tripping your RCD's if your stuff is not in good order and maintained reg

RCD tripping
If yours tripps on you, unplug everything from the socket outlets at source......plug your items in one by one until it trips....thus finding your faulty piece of equipment.

This bit of gear should be tested for faults

One nightmare gig was a marquee! I had asked for a 13a socket, and there was a 13a 4way under my allocated table, However when I looked back down the wire there was also a juke box two big chest freezers of beer and all the lighting running off this lead! THEN this lead whent down the garden to the house as a Black & Decker two core garden extension lead.

Quote Little John:
"THEN this lead whent down the garden to the house as a Black & Decker two core garden extension lead."

Blimey!
Are people still taking these sort of risks??
Ignorance of the facts I suppose, along with the dangers.

I haven't done a marquee gig for many years now, but if I get asked to do another one, I think it might be worthwhile preparing a separate check sheet for the client to sign, containing safety advice on the power supply, along with a declaration that they agree for the supply to be up to the required standards, or there'll be no show. I already have this written into my contract, but as I'm more interested in the supply being safe rather than the client just signing anything put under their noses, a separate sheet may do the trick.

As I've mentioned before (ad nauseam probably), I still bear the 6" scar resulting from surgery required after a near-fatal electrocution due to someone else's dodgy extension lead.

Don't chance with it - insist on everything being up to scratch. RCD devices are so cheap these days, there's no real excuse for not having one at the end of each of your extension leads. You can buy ones which can be wired onto the lead as a plug, which is pretty simple, plus they are right where you need them, so they won't get misplaced in a rush.

I always take some extension leads! there's 50m of 1.5mm and 80m of 2.5mm If I even suspect the power supply I take the UPS as this will double convert and bring a out of spec mains back to volts. Then there is the little buzz generator available on request.

However I do understand the earthing requirements, and bs7909!

Also, any electrical connections outside of the marquee should be a minimum of IP44 rated.

Turned up at a marquee the other week and a normal 13 amp extension lead was outside in the rain -great.

Remember also that its feet indoors and yards outside!

If the client says its 10 feet then indoors it probably is, but outdoors its more like 10 yards! Take enough cable.

Just a reminder everyone with Summer around the corner, Jeff's excellent post from2 years ago.

would i be correct to say an amp that produces 450 rms either side at 8ohm would be 900 w in total when adding up the load for the marque

No, the power output of an amp is the "audio" output.
Check the ratings plate on the amp, it will tell you the power consumption, that is the amout of electric power it requires.

Jim

heres the amp The C-MARK MR2450 G098C Spec.
* 4 ohm Stereo Power: = 700WRMS per channel
* 8 ohm Stereo Power: = 450WRMS per channel
* Inputs: 2 x 6.3mm Jacks, 2 x XLR
* Outputs: 2 x Speakon
* Distortion: <0.1%
* Protectio: Short Circuit, thermal and fan overload
* Signal to Noise Ratio: >104dB
* Input Frequency: 10 k Ohm Balanced
* Frequency Response: 20Hz - 20KH what would this be ?

The info you posted is what you have copied off a website.
Look on the back of the amp, it will state the POWER CONSUMPTION.
It will say something like 220/240 V ac 2.6A or similar.

Jim

found the manual - max current draw 220v 8 amp, nothing about amp ratings on the amp itself

so thats drawing 8 amps then ? whats the max amount of amps for a single socket or a safe limit to keep to

13 amps is the max you can draw from anyone socket.

which is a bit confussing as the t amp 2400 from thoman is rated as 15 amp on the manual. Too much for the socket?

Also IEC plugs/sockets are only rated at 10A :confused:

Jim

I invested in a power consumption monitor from CPC, which is a great investment for less than a tenner, not only does it work out how much common electrical appliances around the home cost to run, but it also shows the real time consumption in Watts and Amps of any piece of equipment, including disco.

I've used this a time or two at marquees, just to make sure i'm not running beyond the limit of the incoming mains.

In practice, I found that the ratings on the back of amplifiers were nowhere near those quoted on the back of the unit or the manual. I have the same C-Mark MR2450 amplifier, and running into an 8 ohm load, the amplifier drew no more than 3.1A all night - at least that was the maximum demand recorded by the consumption monitor during a wedding.

Into a 4 ohm load, at another venue the maxium load peaked at 4.7A

I wasn't thrashing the amplifier by any means, but it was probably running at around 70% of its rated output on both occasions.

I think that manufacturers quote worse case maximum demand figures to cover themselves, I think you'd really have to be hammering the amplifier into a low ohm load for it to draw over 13A, it probably could also be the switch on surge



In order to get their BS rating, a modern approved 13A double outlet plate has to withstand a total of 20A for continuous periods. I've always made it a practice to plug the sound equipment into one outlet, and then the lighting into a seperate one rather than both into the SAME double socket or sharing an extension lead off a single outlet - which is just asking for trouble. I've never had any problems this way, in either venues or marquees.

I had a nice surprise on Saturday. The marquee lighting had been plugged into the power allocated for the entertainment.

What did you do Dan?

Packed up, went home!

Just removed a couple of light effects. Clients happy. No problems.

Like you, i'd be nervous about sharing a socket with 'other' marquee related appliances and would ideally insist on a dedicated supply for the Disco. I've seen this thing happen far too often.

I see the plug marked 'Chandeliers' - I guess this was feeding the house lights?. Well, a couple of chandeliers, each containing several 40w - 60W lamps can add up and make a big dent in the 13A maximum load available from the trailing socket and the incoming Arctic cable only looks capable of about 20A - what was the end of the blue cable plugged into?.

The biggest danger of 'single sourcing' power in this manner, is not only the very real risk of overload or interference (bar pumps, fridges etc) but if the disco blew a fuse or a bulb failing tripped the supply then the entire marquee would be plunged into pitch darkness as well as silence - silence that is, apart from the screams from all of the little darlings who were running around the dancefloor and have just collided with large solid objects

This is a classic example of either the marquee company, or the client skimping on costs.

For large marquees, most decent companies will get an electrician to tap directly into the incoming mains distribution at the house end, run large current carrying SWA cable to the marquee and have a seperate 'consumer' unit and temporary distribution outlets for caterers, bar, disco, house lights and portaloo power etc. Such temporary installations are capable of 40, 60 or even 100A, much more preferable than somebody's old extension lead acting as a single source for all who need power - a very real fire risk - something you really don't need in a marquee. Coconut Grove anyone?

Sadly though, any client likely to question the price of a disco could probably also skimp a few hundred on a proper marquee electrical installation - service provider be warned.

All the more reason to put extra clauses into your contracts for marquee functions. I do.

One of the worst offenders is the tea urn. Uses loads of power.

so basically make sure the lead they provide is not connected to any other power drawing equipment, any other clauses/points ?

Depends entirely on what current your own 'rig' draws. Some minimalistic shows could probably easily work from one 13A socket without any second thought, whilst a mobile nightclub style rig could probably need a whole 32A ring main to itself.

It's Probably safe to assume that an 'average' DJ could probably safely operate from one 13A double socket in a marquee, if that was the only offer on the table, at least if their pride could bear to be parted from their 3kw mega strobe and 22 moving heads

But that allocated socket should be dedicated to the disco, and nothing else. Once other people start plugging into one lead, then their power consumption also has to be deducted from the total load capacity.

So for example, lets assume that you are sharing a socket with the house lights....

Power Available - 13A four gang socket, rated and fused at 13A. At *230v mains voltage that means that there is just about 3kw or 3000W available from that source.

If you (the disco) were the only load on this socket then you would be able to use the full 3000W which the lead is capable of safely suppling.

However if you were also sharing with something else, ie the house lights:-

Lets assume, 2x chandeliers in the marquee, each containing 6x 60W lamps

One Chandalier = 6x 60w bulbs - power consumption 360W each x 2 = a total load of 720W being drawn by these two Chandaliers

So if you are sharing the same 13A supply

3000W - 720w (allocated to house lights) = 2280W left available for the disco from this one source, that isn't a lot.

By the time you've plugged in your 1200W amplifier, Mixer, CD Players and a few 250W lighting effects then you are already sailing dangerously close to overloading the supply and a fire risk, and don't even think of plugging in your 1kw smoke machine in this example .

Some lighting effects like the I-Colour and NJD Quartet can draw as much as 1500W - 2000W just for the one effect, and smoke and haze machines use heating elements which can also be fairly greedy with consumption.

So, the best advice is to inform the client that you need, at least a double 13A socket outlet which is dedicated to the disco and not shared with anything else, either in the marquee or at the building end. If you show draws MORE than 13A, then either reduce it, or inform the client in advance of exactly what you need. Telling them on the day is not an option.

If the client really has no option but to use an ordinary extension lead, then make sure that your total load is going to be less than 13A, that the extension lead is of a decent quality, full unwound and is rated at 13A load. Also make sure that it is plugged into its own socket at the building end.

I've done marquees before now, where a 13a lead at the marquee end has been plugged into an orange 5A flymo lead further up the chain. I've also followed wires back to a house socket where it has been plugged into a mulitway socket along with a kettle and washing machine. People really do not think when they plug in an extension lead, and its really 'any socket will do' attitude, so never assume that the person who plugged the lead in knows what they are doing, check it out for yourself.

(NB *230v is the new european harmonised voltage which was agreed and set as a standard voltage across europe some years ago, and of which the UK is also a member, most of the time the actual voltage is around 230 - 240v, but as a safety margin, its common practice to use 230v in load consumption equations)

Crikey two years ago I posted that!! time flies!

Yeah I agree with the above post, you an easily overload a "ringmain" sockets system by plugging in your gear to a socket outlet that shares power with all sorts of other stuff in the building.
Lets face it, its a little pot luck really, nobody knows whats on the same power ring unless it all goes off!! then you'll find out

best advice is to split your total load into 2 leads.. one for lights, one for audio

Jeff

cheers dudes. going to do that