Polarity Testting


Old 06-21-03, 11:40 PM
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Polarity Testting

Is there a safe way to test polarity with a voltage tester? My tester is kinda old and doesn't have any auto polarity functionality in it.

I'm not that cheap that I wouldn't want to go and get the correct $8, 3 light tester at a hardware store but I never seem to have those little gadgets handy when I need them.

Can I just probe the neutral and ground part of the 3 prong, 115V electrical plug? If the neutral side was hot, then the voltage meter should read something correct? Is this safe?

Last edited by mgeubtn; 06-22-03 at 06:10 AM.
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Old 06-22-03, 10:15 AM
Join Date: Sep 2000
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If you have grounding, then yes, you can test for correct polarity with a voltage tester. All that little $8 tester does anyway is do three simultaneous voltage checks.

A properly wired receptacle will have:
  • Voltage from the narrow slit to the ground hole.
  • Voltage from the narrow slit to the wide slit.
  • No voltage from the wide slit to the ground hole.
Old 06-22-03, 12:47 PM
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Thank you John. I just wanted to let you moderators know what a great job you do with this board. This is the second time I asked a question on here and the return answers were straight forward and quick.

I'm going to be hooking up a manual transfer switch for a generator soon and I seen some great discussions in the archive about how to safely do this. Once again this little forum will come in handy.

Nice work fellas!
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