26 Volts?

[Ron44]

Why would I be getting 26V at a switched outlet when the switch is open? Flip the switch and there's 120V, turn it off and there's 26V at the receptical. It's a new circuit, with an uninterrupted run (12/2) for a garbage disposal.

 

[iwire]

Because your using a DMM when a 'Wiggy' would be a better choice.

NEMA ENGINEERING DEPARTMENT BULLETIN
No. 88
October 1998
Revised February 2003
Phantom Voltages
This Bulletin is intended to address the occurrence of so-called ?phantom? voltages, a phenomenon detected during the testing of electrical conductors in the field.
Due to the high impedance of measuring instruments, a voltage reading may be detected on open conductors where there is no hard electrical connection to a voltage source. Conductors that are installed in close proximity to one another, and are capacitively coupled to each other, can cause this a.c. voltage reading. Such a reading could be 2 or 3 volts, or it may be as high as the voltage on the adjacent conductors. This is what is referred to as a ?phantom? voltage.
According to Underwriters Laboratories Inc., this can be a harmless reading and can be caused by the high input impedance of the measuring instrument, which places very little loading on the circuit under test. The capacitance is increased as the length of the run is increased. A 50-foot run may produce a pronounced capacitance effect whereas a one-foot sample may not produce any.
Since the ?phantom? voltage is a physical phenomenon involving very small values of capacitance, it cannot energize a load or cause physiological damage to a person.
Care must be taken to be sure that the voltage reading is a phantom voltage, which is caused by improper use of high impedance multimeters, and not as a result of a cable defect or improper installation, which may result in a shock hazard.
In order to help minimize the likelihood of reaching a wrong conclusion from this phenomenon, NEMA recommends the use of a Listed low impedance multimeter in place of a high impedance multimeter or other high impedance measuring device for testing on open conductors where there is no hard electrical connection. Without a low impedance measuring device, a high voltage reading is an inconclusive indication of possible faults in the cable.

 

[kevinware]

Bob,

About a year ago I was asked by an in-law to replace a receptacle in an old single family dwelling with two prong receptacles (she was renting this house at the time). The receptacle I was replacing just had some broken plastic on the face and was located in a family room that had been added on (didn't see a green sticker). I turned the breaker off, replaced the receptacle and tested it from hot (black) to ground (white) with my DMM in continuity mode and was reading a short. I went to another receptacle in the same room on the same circuit but further back (closer to the panel) and had the same thing. I turned the breaker back on and measured again and had 120V. Turned breaker off again and measured acrossed the white and equipment ground and had continuity, measured across the black and equipment round and had nothing. The breaker never triped and there were not any other problems that I seen. The circuit seemed to be working. To make a long story short I called the landlord asking permission to trouble shoot further and he started to get angry and asked me to leave and not to do any more work on his property. I never found out what happened and I have never seen the problem again. Would you have an ideal of what could cause this? And just for the record I informed the AHJ that there was work being done at a certin address without a permits..

Thanks for your thoughts,
Kevin

 

[ardy]

Could there have been an item pluged into another recep. on same circuit?

 

[kevinware]

There could have been. What I encountered may not have even been a problem. Any other opinions?

 

[infinity]

There could have been. What I encountered may not have even been a problem. Any other opinions?

I agree with Ardy something was probably plugged in on the same circuit. As an example, plug-in transformer for a cordless phone would read a very low resistance if the circuit were de-energized.

 

[kevinware]

Thanks everyone for the replies. I should have been able to see this but I guess I was so sure that there was a problem that I was hell bent on finding one. It can be embarassing when the brain shuts down.

Thanks,
Kevin

 

[don_resqcapt19]

The same thing that causes "phantom voltages" can also show continuity when using a DMM.
Don

 

[dlhoule]

Do any of you still use a continuity light? Between continuity light and wiggy you can troubleshoot IMO better than 90% of problems in a house.