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Author Topic: TT 30 P question. No neutral - 60 volts each leg  (Read 4329 times)

Kemper Watson

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TT 30 P question. No neutral - 60 volts each leg
« on: June 25, 2023, 11:39:01 AM »

   Yesterday we found a TT 30p on the side of a house where we were providing audio . Homeowner says its what they've used before. They have it adapted down to Edison so I plug in a tester. No neutral. Further inspection show 60 volts from each blade to ground  Measuring across the two blades gave 120 volts..How did this happen? I can't recall seeing 60 volts before..? We abandoned this and found grounded/correct circuits and pulled from them..Thanks for your time!!
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Chris Hindle

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Re: TT 30 P question. No neutral - 60 volts each leg
« Reply #1 on: June 25, 2023, 12:08:28 PM »

   Yesterday we found a TT 30p on the side of a house where we were providing audio . Homeowner says its what they've used before. They have it adapted down to Edison so I plug in a tester. No neutral. Further inspection show 60 volts from each blade to ground  Measuring across the two blades gave 120 volts..How did this happen? I can't recall seeing 60 volts before..? We abandoned this and found grounded/correct circuits and pulled from them..Thanks for your time!!

Look up "Balanced Power." I've seen it used in studios and lab's where electrical "noise" has been a "problem.
Chris.
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Ya, Whatever. Just throw a '57 on it, and get off my stage.

Tim McCulloch

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Re: TT 30 P question. No neutral - 60 volts each leg
« Reply #2 on: June 25, 2023, 01:24:40 PM »

Never seen balanced power on an RV TT30.  The connector is listed for 120v 30 amp service with a neutral and ground.
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Geoff Doane

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Re: TT 30 P question. No neutral - 60 volts each leg
« Reply #3 on: June 25, 2023, 01:37:16 PM »

   Yesterday we found a TT 30p on the side of a house where we were providing audio . Homeowner says its what they've used before. They have it adapted down to Edison so I plug in a tester. No neutral. Further inspection show 60 volts from each blade to ground  Measuring across the two blades gave 120 volts..How did this happen? I can't recall seeing 60 volts before..? We abandoned this and found grounded/correct circuits and pulled from them..Thanks for your time!!

Abandoning it was probably the right decision.

If you used a DVM (high input impedance) and the ground wire was not actually connected at the panel end, you might measure roughly 60V on each of the other two wires.  The long wire would create a capacitive voltage divider, with the "ground" wire floating up to 60V.

GTD
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frank kayser

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Re: TT 30 P question. No neutral - 60 volts each leg
« Reply #4 on: June 25, 2023, 02:00:15 PM »


I've seen 60+60 on a number of gensets i.e., Honda EU1000i, and some larger Hondas on portable stage rigs, and have used them without issue. 


I cannot comment on your particular situation.


frank
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Steve Crump

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Re: TT 30 P question. No neutral - 60 volts each leg
« Reply #5 on: June 25, 2023, 02:25:43 PM »

   Yesterday we found a TT 30p on the side of a house where we were providing audio . Homeowner says its what they've used before. They have it adapted down to Edison so I plug in a tester. No neutral. Further inspection show 60 volts from each blade to ground  Measuring across the two blades gave 120 volts..How did this happen? I can't recall seeing 60 volts before..? We abandoned this and found grounded/correct circuits and pulled from them..Thanks for your time!!

Not seeing the install or understanding how it is connected up the line, I would say this house has a grounding issue. Usually, you see this when a transformer is part of the circuit and has not been properly bonded. 
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John Roberts {JR}

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Re: TT 30 P question. No neutral - 60 volts each leg
« Reply #6 on: June 25, 2023, 02:55:24 PM »

The obvious question is what is your ground 0V reference for making those measurements? I've seen roughly 1/2 voltage measured wrt a floating ground.

Can the edison outlet support a drop light with one lamp?

What did you use for an outlet tester? The highest likelihood is that you see 120VAC between line and neutral.

Slowly back away... maybe tell the homeowner to wire in a GFCI edison outlet if he must.

JR 
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Kemper Watson

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Re: TT 30 P question. No neutral - 60 volts each leg
« Reply #7 on: June 25, 2023, 03:29:33 PM »

The obvious question is what is your ground 0V reference for making those measurements? I've seen roughly 1/2 voltage measured wrt a floating ground.

Can the edison outlet support a drop light with one lamp?

What did you use for an outlet tester? The highest likelihood is that you see 120VAC between line and neutral.

Slowly back away... maybe tell the homeowner to wire in a GFCI edison outlet if he must.

JR


I have the male Edison plugs with the red/green lights. While I know they're not perfect but when I see red I go looking for something wrong. Went and got the meter and found 60v to ground on each leg. I'm not an electrician so that's all I know to do. I knew once I saw the 60 v I wasn't using it
« Last Edit: June 25, 2023, 03:38:19 PM by Kemper Watson »
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John Roberts {JR}

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Re: TT 30 P question. No neutral - 60 volts each leg
« Reply #8 on: June 25, 2023, 04:03:31 PM »


I have the male Edison plugs with the red/green lights. While I know they're not perfect but when I see red I go looking for something wrong. Went and got the meter and found 60v to ground on each leg. I'm not an electrician so that's all I know to do. I knew once I saw the 60 v I wasn't using it
This is probably TMI but those three lamp testers are not very accurate. In fact they can report a good outlet that isn't.

 If they report a bad outlet, it usually is bad.

 http://johnhroberts.com/OD1.htm


JR
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frank kayser

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Re: TT 30 P question. No neutral - 60 volts each leg
« Reply #9 on: June 26, 2023, 10:57:27 PM »

This is probably TMI but those three lamp testers are not very accurate. In fact they can report a good outlet that isn't.

 If they report a bad outlet, it usually is bad.

 http://johnhroberts.com/OD1.htm


JR
Sure do wish someone could make this tester a reality…
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Re: TT 30 P question. No neutral - 60 volts each leg
« Reply #9 on: June 26, 2023, 10:57:27 PM »


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