ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1] 2  All   Go Down

Author Topic: Could this cause a problem?  (Read 5370 times)

Kevin Conlon

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 256
  • Thanks for being here
Could this cause a problem?
« on: November 04, 2018, 09:40:17 am »

We set up at a car dealer 200 feet from power. Two 123 volt outlets on each side of the breaker pannel, 246 volts total when metered. I made a cable some years ago with two 120 plugs to a stove plug for the distro. I have used it a few times, no problems. When the band is playing hard max draw is around 7-8 amps per leg. My question, is this a safe way to get 240v ? Grounds are tied together. The weird part last week was each leg at the distro was 123 volts yet input volts were 236 or so. I felt safe with it and we used it for hours with no issues. Any ideas on where 10 volts went?. There were no hot skins anywhere that i found and warm wires. So..... safe or not? Never happened before.  Thanks for any insight.   Kevin.
Logged

Mac Kerr

  • Old enough to know better
  • Administrator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6348
  • Audio Plumber
Re: Could this cause a problem?
« Reply #1 on: November 04, 2018, 09:48:36 am »

We set up at a car dealer 200 feet from power. Two 123 volt outlets on each side of the breaker pannel, 246 volts total when metered. I made a cable some years ago with two 120 plugs to a stove plug for the distro. I have used it a few times, no problems. When the band is playing hard max draw is around 7-8 amps per leg. My question, is this a safe way to get 240v ? Grounds are tied together. The weird part last week was each leg at the distro was 123 volts yet input volts were 236 or so. I felt safe with it and we used it for hours with no issues. Any ideas on where 10 volts went?. There were no hot skins anywhere that i found and warm wires. So..... safe or not? Never happened before.  Thanks for any insight.   Kevin.

Not safe, not legal, not OK.

Mac
Logged

Kevin Conlon

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 256
  • Thanks for being here
Re: Could this cause a problem?
« Reply #2 on: November 04, 2018, 09:58:03 am »

Not safe, not legal, not OK.

Mac
I figured someone would say that. I knew it was not legal. Tell me how it is unsafe please, i need an education.
Logged

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3341
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: Could this cause a problem?
« Reply #3 on: November 04, 2018, 11:02:28 am »

I figured someone would say that. I knew it was not legal. Tell me how it is unsafe please, i need an education.

The primary danger is that if you have any amplifiers or other gear operating on 240 volts (two hot legs), and one of the male plugs were pulled out of the receptacle, then there would a cross-connect from the still connected male plug to the disconnected male plug. So that would allow 120 volts to appear on the male contact of the disconnected plug. Since any stove plug (I assume you mean a 14-50 receptacle) is rated for 250 volts, then it's assumed there's a potential for two-pole (240-volt) operation. And if that were to occur, it could create a deadly situation.

Most code isn't there for when things are all perfectly correct. It's there to assure there's sufficient backups for when something goes wrong. For example, there's generally no immediate danger to wiring a receptacle with a bootleg ground. But if the polarity was accidentally reversed, then the chassis would be energized with 120-volts at full current capability. A classic RPBG (Reverse Polarity Bootleg Ground).

And while your wiring scenario might work properly if all other conditions were met perfectly, there's just too many things that could go wrong with it for ANY inspector to OK. That's why it's a definite code violation, and you would carry full responsibility (read liability) if something were to go wrong and someone got hurt (or even killed), or gear was damaged.   

Far better to talk the dealership into wiring in a dedicated 14-50 receptacle on its own 2-pole/50-amp breaker. Then you could just plug in without fooling around with an adapter cable that's sure to give any AHJ a heartburn.   
Logged
Mike Sokol
mike@noshockzone.org
www.NoShockZone.org

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3341
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: Could this cause a problem?
« Reply #4 on: November 04, 2018, 11:12:13 am »

We set up at a car dealer 200 feet from power. When the band is playing hard max draw is around 7-8 amps per leg.

I've done this exact type of gig for some local car dealerships a few times, and if I'm far from power I either use a Honda EU2000i generator (which works great), or a 2kW sine inverter I have wired into my truck battery (which also works great). No wires laying on the ground for vehicles to run over, and no voltage drop from 200 feet of wiring run.
Logged
Mike Sokol
mike@noshockzone.org
www.NoShockZone.org

Kevin Conlon

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 256
  • Thanks for being here
Re: Could this cause a problem?
« Reply #5 on: November 04, 2018, 12:10:52 pm »

The primary danger is that if you have any amplifiers or other gear operating on 240 volts (two hot legs), and one of the male plugs were pulled out of the receptacle, then there would a cross-connect from the still connected male plug to the disconnected male plug. So that would allow 120 volts to appear on the male contact of the disconnected plug. Since any stove plug (I assume you mean a 14-50 receptacle) is rated for 250 volts, then it's assumed there's a potential for two-pole (240-volt) operation. And if that were to occur, it could create a deadly situation.

Most code isn't there for when things are all perfectly correct. It's there to assure there's sufficient backups for when something goes wrong. For example, there's generally no immediate danger to wiring a receptacle with a bootleg ground. But if the polarity was accidentally reversed, then the chassis would be energized with 120-volts at full current capability. A classic RPBG (Reverse Polarity Bootleg Ground).

And while your wiring scenario might work properly if all other conditions were met perfectly, there's just too many things that could go wrong with it for ANY inspector to OK. That's why it's a definite code violation, and you would carry full responsibility (read liability) if something were to go wrong and someone got hurt (or even killed), or gear was damaged.   

Far better to talk the dealership into wiring in a dedicated 14-50 receptacle on its own 2-pole/50-amp breaker. Then you could just plug in without fooling around with an adapter cable that's sure to give any AHJ a heartburn.
Thank you. I understand. Let me point out that when i have used this setup it has never run anything 240 for the reasons you explained. No AHJ here that ever shows up(yet). We are considering a proper size generator or renting next time. This came up overnight, no time to react. I know this is no excuse. Thanks.
P.S.  Any idea where the 10 volt difference came from. this was essentialy a dual 120 rig. 
Logged

Tim McCulloch

  • SR Forums
  • Hero Member
  • *
  • Offline Offline
  • Posts: 19805
  • Wichita, Kansas USA
Re: Could this cause a problem?
« Reply #6 on: November 04, 2018, 01:01:40 pm »

Thank you. I understand. Let me point out that when i have used this setup it has never run anything 240 for the reasons you explained. No AHJ here that ever shows up(yet). We are considering a proper size generator or renting next time. This came up overnight, no time to react. I know this is no excuse. Thanks.
P.S.  Any idea where the 10 volt difference came from. this was essentialy a dual 120 rig.

At the end of your extensions, or at the source?  How much voltage was between neutral and ground at point of service and at the end of your extensions?
Logged
"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Kevin Conlon

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 256
  • Thanks for being here
Re: Could this cause a problem?
« Reply #7 on: November 04, 2018, 04:04:03 pm »

At the end of your extensions, or at the source?  How much voltage was between neutral and ground at point of service and at the end of your extensions?
I did not check! I did not notice till all was up and running. Thanks all, i had to know how wrong i was.
Logged

TJ (Tom) Cornish

  • Hero Member
  • *****
  • Online Online
  • Posts: 4242
  • St. Paul, MN
Re: Could this cause a problem?
« Reply #8 on: November 05, 2018, 08:27:03 am »

Since you didn't use 240 volts, why did you use your distro instead of just using the two extension cords directly?  Your distro doesn't give you any more usable power, and as has been pointed out, increases liability and safety risk fairly significantly.

It's not illegal to combine grounds between multiple circuits - this is in fact the main benefit of the "Poor Man's Distro", the purpose of which is to reduce system noise by bonding grounds of your supply circuits via the power distribution side rather than through all your audio devices.
Logged

Kevin Conlon

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 256
  • Thanks for being here
Re: Could this cause a problem?
« Reply #9 on: November 05, 2018, 09:38:04 am »

Since you didn't use 240 volts, why did you use your distro instead of just using the two extension cords directly?  Your distro doesn't give you any more usable power, and as has been pointed out, increases liability and safety risk fairly significantly.

It's not illegal to combine grounds between multiple circuits - this is in fact the main benefit of the "Poor Man's Distro", the purpose of which is to reduce system noise by bonding grounds of your supply circuits via the power distribution side rather than through all your audio devices.
I needed the distance. 100 feet ext cord, 100 of #8 for distro.
Logged
Pages: [1] 2  All   Go Up
 


Page created in 0.052 seconds with 24 queries.