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Author Topic: 50amp outlets  (Read 28032 times)

Steve M Smith

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Re: 50amp outlets
« Reply #10 on: September 19, 2013, 04:16:50 pm »

In houses here in the UK you will only find one outlet now and that is the standard 13A socket.  I was surprised to see an outlet for an electric oven in the diagram.  These are always hard wired into their own isolating switch with its own connection back to the consumer unit.

In industrial and entertainment premises, there are standard 16A and 63A sockets.

http://upload.wikimedia.org/wikipedia/commons/4/4c/Mated-16A-Plug-And-Socket.jpg


Steve.
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Jonathan Johnson

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Re: 50amp outlets
« Reply #11 on: September 19, 2013, 04:27:07 pm »

My electric range came with a 10-50P on it. I had the cord set replaced before I could use it.

When I moved into my current home, the range receptacle was a 10-50R and the clothes dryer was a 10-30R. Rather than replace the cords on the range & dryer (what most people would probably do) I replaced the receptacles for 14-50R and 14-30R, respectively. Safer that way.
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John Moore

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Re: 50amp outlets
« Reply #12 on: September 19, 2013, 04:52:47 pm »

We will not do an event if the power is not correct, and no ground is a deal breaker. Liability issues and best practices along with sticking to what is right will hopefully prevent and major issue with someone getting shocked, equipment destroyed or damaged. For us it is the right way or no way...
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Jonathan Johnson

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Re: 50amp outlets
« Reply #13 on: September 19, 2013, 05:42:36 pm »

Tech riders and service contracts should specify the power needs, including the connection the venue shall provide. Failure to provide the requested power should allow you to be released from the agreement, possibly with payment. There should also be a clause that you will not plug in if the power supply is unsafe.

Any wiring that is not in compliance with electrical codes and best practices can be considered unsafe.

This isn't about providing a good show, or about protecting your equipment. It is a life safety issue for you, the performers, the patrons, and anyone else in the vicinity.
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Jonathan Johnson

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Re: 50amp outlets
« Reply #14 on: September 21, 2013, 06:40:46 pm »

Tech riders and service contracts should specify the power needs, including the connection the venue shall provide.

Some sample text (I am not a lawyer): "(We) reserve the right to have electrical service inspected by a licensed electrician or certified inspector of our choice prior to connection of equipment. Any deficiencies identified during inspection shall be rectified prior to connection."
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Jamin Lynch

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Re: 50amp outlets
« Reply #15 on: September 29, 2013, 04:03:05 am »

Another issue that often comes up is when the only available power at a venue is an old style 50amp outlet with no ground.

What's a good option to get you safely through the night?

Thanks

Well here ya go.

Did a small town festival yesterday. Pulled up to the stage and I was told power is already hooked up for us. All they need to do is plug it in. Here's what I found. 50amp plug no ground. The cord was about 100ft of 12 gauge SJ cable. There was no other power available. So what do I do? I installed my own set of breakers in the panel next to the plug and called it good. Everything went well.

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Scott Wagner

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Re: 50amp outlets
« Reply #16 on: September 29, 2013, 10:12:43 am »

Did a small town festival yesterday. Pulled up to the stage and I was told power is already hooked up for us. All they need to do is plug it in. Here's what I found. 50amp plug no ground. The cord was about 100ft of 12 gauge SJ cable. There was no other power available. So what do I do? I installed my own set of breakers in the panel next to the plug and called it good. Everything went well.
...and when the place burns down in a month or two, they'll be naming YOU in the lawsuit.  If you work inside the breaker box, you assume liability.  I'll bet your insurance carrier doesn't cover this, either.
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Scott Wagner
Big Nickel Audio

Craig Hauber

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Re: 50amp outlets [o/t swerve]
« Reply #17 on: September 29, 2013, 11:38:33 am »

I have one of those plug/recep setups on my kitchen range.  Is it safe to use or should I upgrade it to 4-wire? 
-Why I ask is that there's newer stainless appliances right next to it with proper grounding and was wondering if someone is touching the stove and the fridge at the same time could there ever be an issue?
It's a 1920's house that got rewired in the late 80's (new panel, service entrance and romex for most of the interior wiring)  The existing stove wiring just got re-connected to the new panel. 



Hmmmm..... I see a lot of 3-wire 30-amp/240-volt dryer outlets with a single ground/neutral contact in older buildings, but I can't remember seeing any 3-wire 50-amp/240-volt outlets in recent memory. But they're entirely possible. Since you're working from a new ground-neutral bonding point, any current on the line conductor will create a voltage drop in that side of the line, which will cause an equal and opposite voltage drop in the neutral conductor. Since your ground wire is also the neutral wire in that case the safety ground voltage will move around a lot, perhaps as much as 10 volts or so.  That suggests you'll want to avoid connecting some of your sound or stage gear to any other receptacles in the building unless you use audio isolation transformers such as a Whirlwind ISO-2 or similar, and you'll certainly want good DI's with a ground lift switch in the "lift" position. If you do cross connect something with shied isolation, lets say the amp rack connected to the 30 or 50-amp/240-volt 3-wire outlet and the mixing console to a handy Edison outlet on the back wall, you'll create a classic ground loop problem and lots of hum. In fact, I think this would be an excellent GLID (Ground Loop Inter-modulation Distortion) situation where power being pulled from the power amp rack will induce 60-Hz ground loop hum that you'll hear only during bass transients (Don't Doubt the GLID). ;D 

So, the basic rule is it. Either EVERYTHING is powered from your own distro connected to this 3-wire, 50-amp/240-volt outlet, or you need to provide audio isolation transformers between gear on the two power feeds. And you might be able to get away with pin-1 lifts on the XLR inputs depending on the CMRR of your balanced inputs on the amp rack. But I personally would avoid cross connecting gear powered between standard Edison wall outlets and your 3-wire distro in general. Too many things to go wrong.
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Craig Hauber
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Jamin Lynch

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Re: 50amp outlets
« Reply #18 on: September 29, 2013, 11:43:04 am »

...and when the place burns down in a month or two, they'll be naming YOU in the lawsuit.  If you work inside the breaker box, you assume liability.  I'll bet your insurance carrier doesn't cover this, either.

Uh....it was outdoors.  How could I burn the place down? If the place was going to "burn down" as you say, it wouldn't happen 2 months from now.

So you would just walk away from this job leaving the hundreds of people out of luck who came to see the bands when there was a SAFE and easy alternative to obtain proper power. Would you prefer I use the plug they had for me? I feel that was way less safe than adding a couple of breakers.
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Cailen Waddell

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Re: 50amp outlets
« Reply #19 on: September 29, 2013, 12:45:56 pm »


Uh....it was outdoors.  How could I burn the place down? If the place was going to "burn down" as you say, it wouldn't happen 2 months from now.

So you would just walk away from this job leaving the hundreds of people out of luck who came to see the bands when there was a SAFE and easy alternative to obtain proper power. Would you prefer I use the plug they had for me? I feel that was way less safe than adding a couple of breakers.

I believe the point is unless you are a licensed electrician then there was no safe and easy alternative.  My understanding of the world of liability is now that you have touched the inside of the panel, you are responsible for everything connected to it, including that unsafe 50amp connector.  Anything that happens, from electrocution, to electrical fires etc, to that panel from now on is your responsibility until someone else opens it, then it is their problem.

Do you walk away?  I would. In the rare instances when I have needed to do that, electricians would magically appear to fix the problem rather than not have show.  Itsa amazing how a promoter/club owner will do things right when the alternative is no gig/show/party. 
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