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Author Topic: Hazardous Energy  (Read 4523 times)

Mike Sokol

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Hazardous Energy
« on: July 25, 2017, 10:52:27 AM »

I was helping a buddy of mine troubleshoot his little Peavey mixer last night, and I found this warning in the owner's manual.

"Warning. The power switch in this unit breaks only one side of the line. There may be hazardous energy present inside the mixer when the power switch is in the OFF position."

Of course, if the hot and neutral lines were swapped in the wall receptacle, then turning the switch OFF would open the neutral line and allow everything else inside the mixer before the power transformer to be energized. I don't trust just turning off the power before reaching my hand inside of a piece of gear. I make sure it's unplugged first.

John Roberts {JR}

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Re: Hazardous Energy
« Reply #1 on: July 25, 2017, 12:05:51 PM »

I am a little surprised to see a 3 wire line cord on a small PV mixer. Back in my day we had some cheap double insulated power transformers capable of powering the small mixers. The 3 wire line cords were mainly used on the bigger, more professional SKUs.

I am glad to see them still screening jack connection legends on the back... I started doing that back in the 80's before the industry settled on pin 2 hot for XLRs... The worst thing is trying to troubleshoot interfaces when you don't know what is inside the mixer.

JR 
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Stephen Swaffer

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Re: Hazardous Energy
« Reply #2 on: July 25, 2017, 12:34:05 PM »

That jack is labeled 100-240 volts-a 240 volt line would have 2 hots. 
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Mike Sokol

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Re: Hazardous Energy
« Reply #3 on: July 25, 2017, 12:35:47 PM »

That jack is labeled 100-240 volts-a 240 volt line would have 2 hots.

Not in the UK. It would have a neutral and a single hot, but the hot would be around 230 volts above the neutral and ground.

Stephen Swaffer

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Re: Hazardous Energy
« Reply #4 on: July 25, 2017, 02:05:44 PM »

Not in the UK. It would have a neutral and a single hot, but the hot would be around 230 volts above the neutral and ground.

We're not in the UK :)...
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Mike Sokol

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Re: Hazardous Energy
« Reply #5 on: July 25, 2017, 02:06:56 PM »

We're not in the UK :)...

Oh I see. But who would run a little mixing board like that on 240 volts in the USA?  ;D
« Last Edit: July 25, 2017, 02:14:48 PM by Mike Sokol »
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John Roberts {JR}

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Re: Hazardous Energy
« Reply #6 on: July 25, 2017, 02:16:41 PM »

OK sounds like an universal switcher.... The first one of those I did (last century) was used in a higher end monitor mixer, that was low volume and higher priced so it made more sense. Now I suspect the cost of a universal PS are much lower, probably low enough to standardize on just one PS for all products.

For some inside baseball, when I was researching the desirability of using universal PS in Peavey products some of the international distributors didn't like the idea... Especially the distributor for South America who had both 120V and 240V countries inside his territory. He was worried about gray market transhipping, where say a big dealer in a 120V country could sell goods unofficially into the 240V country and vice-versa harming the integrity of the different dealer's exclusive territories.

I am afraid to even think about how tangled up it is now...  ::)  When we started making drums in China, we discovered that some had walked out the factory back door and ended up in Italy of all countries... Trust but verify or in other words don't trust.  8)

JR
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Stephen Swaffer

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Re: Hazardous Energy
« Reply #7 on: July 25, 2017, 04:35:13 PM »

Oh I see. But who would run a little mixing board like that on 240 volts in the USA?  ;D

The guy that buys 3 wire feeder cable to run xxx feet to his system.  If all of his gear will run on 240, it would be safer to run everything on 240 and use the third wire as a ground rather than bottlegging a neutral off of it. :D
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Steve Swaffer

Stephen Kirby

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Re: Hazardous Energy
« Reply #8 on: July 25, 2017, 04:59:34 PM »

The guy that buys 3 wire feeder cable to run xxx feet to his system.  If all of his gear will run on 240, it would be safer to run everything on 240 and use the third wire as a ground rather than bottlegging a neutral off of it. :D
Wouldn't that more likely be 208?  Same effect though.

There've been a few times when I've installed some industrial piece of equipment that actually did need 230-240 single phase.  And usually been a hassle finding it in the factory.  Usually end up putting a transformer in.
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Stephen Swaffer

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Re: Hazardous Energy
« Reply #9 on: July 25, 2017, 07:47:57 PM »

Depends on where you are at.  In my neck of the woods there are plenty of locations with 120/240-especially parks, fairgrounds and such that make decent size venues for events.

Just tossed it out as a thinking outside the box solution-that might actually be a neat solution once in a blue moon.  Not sure I'd build a distro based on 208-240 only, but it actually might prove less problematic to do that and carry travel converter for the odd piece that has to have 120 VAC.
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Steve Swaffer

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Re: Hazardous Energy
« Reply #9 on: July 25, 2017, 07:47:57 PM »


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