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[g'bye, Dick Rees]

If you're setting up any kind of gear at all in an area where other people will be using it and/or passing around, over or under it, you should be insured for liability.  Even if the event sponsor has a liability policy and signs you off on a hold-harmless rider, you don't want to go to court with that.

[Scott Holtzman]

And, yes, the issues with shocks were from many years ago. Not something I've experienced at all with my current rig. Using tube amps in good condition and recently purchased mixer/powered speakers.

Using the dryer plug is not acceptable.  Dryer plug is three wires two phases and a neutral.  Without a safety ground.

Now you can take the ground out and connect it to a regular outlet but this is not to the NEC because the safety ground can be disconnected without disconnecting the mains.

Code requires all sub panels (this application is a sub panel) to have four wires of the appropriate size, period, end of conversation. 

Do people make other temporary accommodations every day?  Of course they do.  Is it safe, no?  Is it right, no.  Does it void your liability coverage, for sure.

[Ray Aberle]

Using the dryer plug is not acceptable.  Dryer plug is three wires two phases and a neutral.  Without a safety ground.

Now you can take the ground out and connect it to a regular outlet but this is not to the NEC because the safety ground can be disconnected without disconnecting the mains.

Code requires all sub panels (this application is a sub panel) to have four wires of the appropriate size, period, end of conversation. 

Do people make other temporary accommodations every day?  Of course they do.  Is it safe, no?  Is it right, no.  Does it void your liability coverage, for sure.

... Scott, who said anything about using the dryer plug?? 

[g'bye, Dick Rees]

... Scott, who said anything about using the dryer plug?? 

Me!  Me!  I know!!

No one.

There was a range plug mentioned...

[Stephen Swaffer]

Both range and dryer plugs used to be 3 wire.  NEC requires (I think since 2005 or 2008) both to be 4 wire.  Age of house/local codes/inspection requirements will determine what is installed.

No doubt, eventually you will start to see 4-wire receptacles with bootleg grounds-just human nature!

[g'bye, Dick Rees]

Both range and dryer plugs used to be 3 wire.  NEC requires (I think since 2005 or 2008) both to be 4 wire.  Age of house/local codes/inspection requirements will determine what is installed.

No doubt, eventually you will start to see 4-wire receptacles with bootleg grounds-just human nature!

Thus the need for a Fluke meter and the knowledge of how to use it.

To the OP:

It's not really a simple question...

[Ray Aberle]

Me!  Me!  I know!!

No one.

There was a range plug mentioned...

$2 will get you who mentioned the range plug... :-P

But really, these are all of the joys that come with doing something correctly! As the saying goes, integrity is doing the right thing when no one is looking-- it doesn't matter if you'll get inspected or not, you should always endeavor to be as complete as possible.

[Scott Holtzman]

I get to say it again learn something new.  Never seen a four prong range in anything but commercial.  l

[Mike Sokol]

In either case, I should be mindful of the total current draw of all devices being used on stage. One quick question regarding that: should I include every stomp box being used by guitarists, or just the requirements of the pedalboard power supplies (pedal power in both cases)? I'd think the latter, but as you can tell I'm not an electricity expert so figure it's worth checking.

No need to count up the stomp box and pedalboard power supplies. Those things draw next to nothing. Heck, we used to run them all from 9-volt batteries. But you do need to determine the current draw of your power amps and monitors, as well as the musician's stage amps, especially bass amps and tube guitar amps.

However, this total calculation is not always simple since you have to take into account the crest factor and SPL of music you're expecting to do (no kidding). Let consider two different types of acts with vastly different power draw. First up is a rather quiet Celtic act with female singers, pipes and a violin. In that case your amplifiers will be coasting along and probably not drawing much over idle current, perhaps 1/10 of rated wattage with a crest factor of 10:1 (peak to average level) or higher. So even a 450-watt speaker might be drawing only 40 or 50 watt for this act. Now imagine you've got a Reggae or Hip-Hop act up next with LOTS of bass. In that case, your crest factor might approach 1:1. That means that your 450-watt speaker will likely be drawing full power for long periods of time. And since amplifiers are not 100% efficient, it's likely to be drawing more like 600 watts or so.

Now, those of us who do live sound for a living get a pretty good feel of what we can get away with for different acts and styles of music. So I would probably do the Celtic act from a single 20-amp service and not have any problems. But I would certainly want to pull out the big guns with a heavy 50-amp/240-volt (or even more amperage) distro when I'm doing a Reggae or Hip-Hop act.

Also realize that you might find that someone has installed a bunch of lights under the tent and expects to power everything from your generator or distro when the sun goes down. After all, they see all those big cables and assume you've got LOTS of extra power to spare. So make sure you're not responsible for lighting power as well.   

That being said, what kind of acts are expected and how loud will it be? And do I have to power any lights. That's how I always start to calculate power requirements for a gig.

[Mike Sokol]

I get to say it again learn something new.  Never seen a four prong range in anything but commercial.  l

Scott (and everyone else). Try not to fixate on the range/dryer plug question and lets try to help this guy. He's obviously trying to learn something about AC power, so lets teach... 

[ProSoundWeb Community]