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Author Topic: Venue with NEMA 10-50R side stage  (Read 1660 times)

Steve-White

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Re: Venue with NEMA 10-50R side stage
« Reply #20 on: January 11, 2022, 10:25:50 AM »

^^^ A second amp and both on 20A 125V power is a good solution.
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Tim McCulloch

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Re: Venue with NEMA 10-50R side stage
« Reply #21 on: January 11, 2022, 11:18:25 AM »

Thanks for all the great info everyone.

I plan on expanding my power distribution inventory, but to get by for this gig (assuming I can verify the powrrsoft will take two hot legs in place of a hot and a neutral) is to make an adapter from 10-50P to L6-20 but instead of connecting the ground to the neutral, clamping the ground conductor to the breaker panel chassis or exposed grounding conductor. Is this excessively sketchy/illegal or will it be safe?

Absolutely do not bond neutral and ground downstream of the "point of service".  Where you find a ground and how you connect it, I'm not offering suggestions on a public forum... ;)
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Douglas Cyr

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Re: Venue with NEMA 10-50R side stage
« Reply #22 on: January 12, 2022, 06:01:03 PM »

Alright everyone,

So I talked to Powersoft support and they corroborated what some said on here: the K20 will operate fine with two hot legs across the terminals rather than a hot and a neutral, and, if the neutral is bonded to ground I can substitute the neutral of the receptacle for the grounding conductor. So I can essentially make an adapter using all three conductors of the 10-50R directly into the K20 (this isn't considering the 30 amp breaker I will need ofcourse.
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Brian Jojade

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Re: Venue with NEMA 10-50R side stage
« Reply #23 on: January 12, 2022, 11:46:15 PM »

Alright everyone,

So I talked to Powersoft support and they corroborated what some said on here: the K20 will operate fine with two hot legs across the terminals rather than a hot and a neutral, and, if the neutral is bonded to ground I can substitute the neutral of the receptacle for the grounding conductor. So I can essentially make an adapter using all three conductors of the 10-50R directly into the K20 (this isn't considering the 30 amp breaker I will need ofcourse.

Of course you CAN do that, but what you are doing is NOT code.  You should strongly push for the venue to install the PROPPER connector for this type of use.
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Brian Jojade

Steve-White

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Re: Venue with NEMA 10-50R side stage
« Reply #24 on: January 13, 2022, 12:27:07 AM »

Of course you CAN do that, but what you are doing is NOT code.  You should strongly push for the venue to install the PROPER connector for this type of use.

Read and heed.

The question isn't will it work?  Yes it will work.

The question is should you do it?  The answer is a resounding no.  The liability isn't worth the risk to connect to an illegal hodge-podge setup.
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Stephen Swaffer

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Re: Venue with NEMA 10-50R side stage
« Reply #25 on: January 13, 2022, 12:41:45 PM »

I second Brian and Scott.  The problem is most people look at grounds and neutrals as "the same" since they are connected together.  A couple of thoughts:

1.  IF this is a (properly wired) subpanel, the grounds and neutrals will be separate in the panel-connected at the main service panel.  Still connected, right?  Yes, but consider if there is 1/10 ohm resistance on the neutral wire back to the main panel and 20 amps unbalanced current flowing-that works out to a 2 volt voltage drop (working as an electrician, I expect to see this voltage drop-it is routine)-if your amp is connected to a mixer/source that is properly grounded, you potentially have 2 volts AC hum on your subs-which will amplify that nicely.

2.  Heating and cooling of connections is a major source of connections "going bad".  Code does not allow "objectionable" current on grounding conductors so they never have a heat/cool cycle to work things loose.  It is far more likely to have a less than ideal connection on a neutral than on a ground.  If you connect the frame of your Powersoft to that neutral and there is an issue with that neutral, the frame of your amp will be raised to a voltage potential that could be hazardous.

Yes it will work-until it doesn't and in this case "not working" would be hazardous to people and equipment.  Is it worth the risk?
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Steve Swaffer

Jonathan Johnson

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Re: Venue with NEMA 10-50R side stage
« Reply #26 on: January 13, 2022, 01:59:13 PM »

Stick a wet shirt on the Powersoft, and if anyone asks...

"But, Mr. Inspector, that's not a power amplifier, it's a clothes dryer and falls under the exception provided in NEC 250.140!"

(The above is an attempt at humor. Not a serious suggestion. The exception is ONLY for ranges, cooktops, ovens, and clothes dryers.)

In the event that this receptacle is provisioned through a subpanel (where neutral and ground are NOT bonded) rather than a service entrance (where neutral and ground ARE bonded), a failure of the neutral connection upstream of the subpanel could energize the chassis (and, potentially, connected devices) for the amplifier.

That is, if the neutral fails, the return path for current for other devices provisioned through the subpanel would then be through the neutral-aka-ground to the chassis of the Powersoft and (possibly) other devices connected through the shield of an interconnect cable. This could cause an overcurrent in those shields that overheats them, and poses a shock hazard to personnel.

If the receptacle is provisioned directly from a service entrance, then the only differences from a properly wired NEMA 6-50 (250V 50A 2-pole w/g) are the form factor of the prongs and the color of the conductors.
« Last Edit: January 13, 2022, 02:10:46 PM by Jonathan Johnson »
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ProSoundWeb Community

Re: Venue with NEMA 10-50R side stage
« Reply #26 on: January 13, 2022, 01:59:13 PM »


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