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[Douglas R. Allen]

I work quite a bit at a local club. The stage has 4 - wall mounted quad boxes. In each box 1 receptacle is on 1 phase. The other one on another phase. Measuring with my fluke gets me 219 volts between the hot legs.  Across the room there is 2 receptacles available for FOH.

I am using a M32r digital board-Behringer Cat5e snake with correctly bonded shells , and a DL16 stage box.  I've always run power to the mixer and stage box from the same receptacle at the stage.  I've wanted to not run power along with the snake up and over across the room. Eliminate a step if you will.

With the room closed but available to use today I took a long extension cord and plugged it into the normal outlet I use on stage and ran it to FOH. In one FOH receptacle Stage hot to FOH hot yielded 219 volts so they were on a different phase.

In the 2nd outlet Stage Hot to FOH hot gave me phantom readings.  Stage Neutral to FOH Neutral gave me phantom readings.  Stage ground to FOH ground gave me a steady .21 micro volts so there is a little leakage somewhere.  It seems these Stage and FOH pair are on the same phase/circuit.

My question is this.  When I go from Stage Hot to FOH Neutral or Ground I get 122 volts.   When I go from FOH Hot to Stage Neutral or Ground I get a steady 120 volts.  I'm guessing the FOH circuit has more on it or could it be something else?

Any problems with my testing?


Thanks for any information!
Douglas R. Allen

[Dave Garoutte]

Put a UPS at FOH and on the stage box.

[Tim McCulloch]

I work quite a bit at a local club. The stage has 4 - wall mounted quad boxes. In each box 1 receptacle is on 1 phase. The other one on another phase. Measuring with my fluke gets me 219 volts between the hot legs.  Across the room there is 2 receptacles available for FOH.

I am using a M32r digital board-Behringer Cat5e snake with correctly bonded shells , and a DL16 stage box.  I've always run power to the mixer and stage box from the same receptacle at the stage.  I've wanted to not run power along with the snake up and over across the room. Eliminate a step if you will.

With the room closed but available to use today I took a long extension cord and plugged it into the normal outlet I use on stage and ran it to FOH. In one FOH receptacle Stage hot to FOH hot yielded 219 volts so they were on a different phase.

In the 2nd outlet Stage Hot to FOH hot gave me phantom readings.  Stage Neutral to FOH Neutral gave me phantom readings.  Stage ground to FOH ground gave me a steady .21 micro volts so there is a little leakage somewhere.  It seems these Stage and FOH pair are on the same phase/circuit.

My question is this.  When I go from Stage Hot to FOH Neutral or Ground I get 122 volts.   When I go from FOH Hot to Stage Neutral or Ground I get a steady 120 volts.  I'm guessing the FOH circuit has more on it or could it be something else?

Any problems with my testing?


Thanks for any information!
Douglas R. Allen

Ground voltage in millivolts or microvolts is not a problem.  Seeing 219 volts between supply line phases indicates that incoming power is a little over-voltage (or the venue transformer is tapped to deliver slighter higher voltage).

I guess I'm not seeing the problem here (but I'm on my first cup of coffee so maybe I missed something).

FWIW, we tape AC cable to our snakes (the analog multi, we still need analog pairs for Clear Com and talk backs).  I can't imagine not doing so after 35 years.  Call me a Luddite but I don't understand the hatred that cables get... they're the lifeline of our business.

[John Roberts {JR}]

Ground voltage in millivolts or microvolts is not a problem.

yup

Seeing 219 volts between supply line phases indicates that incoming power is a little over-voltage (or the venue transformer is tapped to deliver slighter higher voltage).

single phase AFAIK... 219 hot to hot /2 is pretty close to 110V

I guess I'm not seeing the problem here (but I'm on my first cup of coffee so maybe I missed something).

not enough coffee...

JR

FWIW, we tape AC cable to our snakes (the analog multi, we still need analog pairs for Clear Com and talk backs).  I can't imagine not doing so after 35 years.  Call me a Luddite but I don't understand the hatred that cables get... they're the lifeline of our business.

[Douglas R. Allen]

I work quite a bit at a local club. The stage has 4 - wall mounted quad boxes. In each box 1 receptacle is on 1 phase. The other one on another phase. Measuring with my fluke gets me 219 volts between the hot legs.  Across the room there is 2 receptacles available for FOH.

I am using a M32r digital board-Behringer Cat5e snake with correctly bonded shells , and a DL16 stage box.  I've always run power to the mixer and stage box from the same receptacle at the stage.  I've wanted to not run power along with the snake up and over across the room. Eliminate a step if you will.

With the room closed but available to use today I took a long extension cord and plugged it into the normal outlet I use on stage and ran it to FOH. In one FOH receptacle Stage hot to FOH hot yielded 219 volts so they were on a different phase.

In the 2nd outlet Stage Hot to FOH hot gave me phantom readings.  Stage Neutral to FOH Neutral gave me phantom readings.  Stage ground to FOH ground gave me a steady .21 micro volts so there is a little leakage somewhere.  It seems these Stage and FOH pair are on the same phase/circuit.

My question is this.  When I go from Stage Hot to FOH Neutral or Ground I get 122 volts.   When I go from FOH Hot to Stage Neutral or Ground I get a steady 120 volts.  I'm guessing the FOH circuit has more on it or could it be something else?

Any problems with my testing?


Thanks for any information!
Douglas R. Allen

Thanks for the replies.

Its a very old building. I remember when the stage was moved to where it is now in 1991. Same boxes and in very bad condition. In my area I have seen ranges from 210 to 230 volts when connecting 2 hots of different phases.  My idea again was to not run 120v power from the stage to FOH but still safely use the digital snake/stage box. I've heard its the best practice to have the stage box and FOH desk on the same phase.  I believe my testing shows both outlets to be on the same phase, neutral, and ground.  When I test power in venues I always was looking to avoid any phase, ground problems.  If I saw some voltage between grounds of different boxes I'd avoid using them. Also keeping everything on the same phase if the voltage requirements would work with the available power.  I've seen as high as 4 volts between ground pins in different locations at other venues so I would not use them. I was unsure if this ground voltage (.21 mico volts ) may mean the 2 outlets, FOH and Stage would not be ok to use together as power sources between the digital stage box at stage and the FOH desk.


I've never been a just plug it in and see what happens kind of person. I have seen threads in other chat groups where people have used FOH on one phase and the stage box on stage on another phase with no problems but if I can keep both on the same phase I feel its worth a quick test to see.


Unless I'm missing something ? I'll give it a try this weekend.
Thanks again;
Douglas R. Allen

     

[Tim McCulloch]

Thanks for the replies.

Its a very old building. I remember when the stage was moved to where it is now in 1991. Same boxes and in very bad condition. In my area I have seen ranges from 210 to 230 volts when connecting 2 hots of different phases.  My idea again was to not run 120v power from the stage to FOH but still safely use the digital snake/stage box. I've heard its the best practice to have the stage box and FOH desk on the same phase.  I believe my testing shows both outlets to be on the same phase, neutral, and ground.  When I test power in venues I always was looking to avoid any phase, ground problems.  If I saw some voltage between grounds of different boxes I'd avoid using them. Also keeping everything on the same phase if the voltage requirements would work with the available power.  I've seen as high as 4 volts between ground pins in different locations at other venues so I would not use them. I was unsure if this ground voltage (.21 mico volts ) may mean the 2 outlets, FOH and Stage would not be ok to use together as power sources between the digital stage box at stage and the FOH desk.


I've never been a just plug it in and see what happens kind of person. I have seen threads in other chat groups where people have used FOH on one phase and the stage box on stage on another phase with no problems but if I can keep both on the same phase I feel its worth a quick test to see.


Unless I'm missing something ? I'll give it a try this weekend.
Thanks again;
Douglas R. Allen

   

Small differences between measured voltage on the same phase lines can be attributed to individual circuit loading, the difference in wire run length between the outlets you are measuring from, etc.  I don't see a problem.  Just for fun you can use a clamp-around ammeter to check for current on your CAT snake... I'd be surprised if you find any.  Mike Sokol has written about measuring several Amperes of current on analog snake shields when there are cumulative hot/neutral and grounding failures.

@JR - I was presuming 2 legs of 3 phase, not split phase, but I think you're right after considering the age of the venue or possible existence of high-leg Delta service.

[John Roberts {JR}]

Thanks for the replies.

Its a very old building. I remember when the stage was moved to where it is now in 1991. Same boxes and in very bad condition. In my area I have seen ranges from 210 to 230 volts when connecting 2 hots of different phases.  My idea again was to not run 120v power from the stage to FOH but still safely use the digital snake/stage box. I've heard its the best practice to have the stage box and FOH desk on the same phase.  I believe my testing shows both outlets to be on the same phase, neutral, and ground.  When I test power in venues I always was looking to avoid any phase, ground problems.  If I saw some voltage between grounds of different boxes I'd avoid using them. Also keeping everything on the same phase if the voltage requirements would work with the available power.  I've seen as high as 4 volts between ground pins in different locations at other venues so I would not use them. I was unsure if this ground voltage (.21 mico volts ) may mean the 2 outlets, FOH and Stage would not be ok to use together as power sources between the digital stage box at stage and the FOH desk.


I've never been a just plug it in and see what happens kind of person. I have seen threads in other chat groups where people have used FOH on one phase and the stage box on stage on another phase with no problems but if I can keep both on the same phase I feel its worth a quick test to see.


Unless I'm missing something ? I'll give it a try this weekend.
Thanks again;
Douglas R. Allen

   

Not to be overly pedantic and this is confusing, but the two hots you are measuring across are considered the same phase in electrician/power terms... They may be opposite polarity but are from the same phase, in the context of 3 phase power with three different phases that are each spaced 120' apart.

JR

[Douglas R. Allen]

Not to be overly pedantic and this is confusing, but the two hots you are measuring across are considered the same phase in electrician/power terms... They may be opposite polarity but are from the same phase, in the context of 3 phase power with three different phases that are each spaced 120' apart.

JR

JR; 

Thank you for the correction. I'm hear to learn. I guess I'm looking for the same polarity then?

Douglas R. Allen

[Don T. Williams]

Not to be overly pedantic and this is confusing, but the two hots you are measuring across are considered the same phase in electrician/power terms... They may be opposite polarity but are from the same phase, in the context of 3 phase power with three different phases that are each spaced 120' apart.

JR

I think you tried to type the degree symbol, but it came out as " ' ".  They could be 120 feet apart, but there should be 120 degrees of difference in the three phases.

[Tim McCulloch]

I think you tried to type the degree symbol, but it came out as " ' ".  They could be 120 feet apart, but there should be 120 degrees of difference in the three phases.

The degree sign isn't an easy one in Windows.  ALT + 0176 is what it takes.  °°°

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