Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums > AC Power and Grounding

TT 30 P question. No neutral - 60 volts each leg

(1/6) > >>

Kemper Watson:
   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!!

Chris Hindle:

--- Quote from: Kemper Watson 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!!

--- End quote ---

Look up "Balanced Power." I've seen it used in studios and lab's where electrical "noise" has been a "problem.
Chris.

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

Geoff Doane:

--- Quote from: Kemper Watson 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!!

--- End quote ---

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

frank kayser:

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

Navigation

[0] Message Index

[#] Next page

Go to full version