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Do you use non-contact voltage test instruments to verify ABSENCE of voltage?
Yes - with protective grounds
Yes - no grounds
No
Nothing above 1,000 volts
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ekstra   ara
 Post subject: Non-contact voltage test instruments ABSENCE of voltage
PostPosted: Sun Sep 18, 2022 7:51 am 
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As part of establishing an electrically safe work condition, NFPA 70E permits the use of non-contact voltage instruments on systems above 1000 volts to test each phase conductor.
An informational note is also provided: for additional information on rating and design requirements for voltage detectors, refer to IEC 61243-1, Live Working — Voltage Detectors — Part 1: Capacitive type to be used for voltages exceeding 1kV a.c., or IEC 61243-2, Live Working — Voltage Detectors — Part 2: Resistive type to be used for voltages of 1kV to 36 kV a.c., or IEC 61243-3, Live Working — Voltage Detectors.
These standards fall under the IEC committee that I chair. According to IEC 61243-1, the presence of voltage shall not appear if the voltage to earth on the part to be tested is less than 10% of the nominal voltage. (not exactly absence of voltage)

The question:
Do you use non-contact voltage test instruments to verify ABSENCE of voltage?
Yes - with protective grounds
Yes - no grounds
No
Nothing above 1,000 volts

Your thoughts are encouraged and welcomed!


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 Post subject: Re: Non-contact voltage test instruments ABSENCE of voltage
PostPosted: Mon Sep 19, 2022 6:05 am 

Joined: Fri Sep 24, 2021 7:17 am
Posts: 28
This is very interesting.......so less than 10% of the nominal voltage is considered as "voltage is absent"? This means that <1500VAC present on a 15kV system is considered as "voltage is absent" then?!!! How can that be? Is it a limitation of the testing instrument/technology being used?

I recently had a discussion about AVT's that are typically used on industrial control panels and the manufacturer stated that their device shows "no voltage present" when the voltage is less than 3VAC. My client and I both still weren't even excited about that....and it's far less than 10% of 480VAC.


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 Post subject: Re: Non-contact voltage test instruments ABSENCE of voltage
PostPosted: Mon Sep 19, 2022 6:38 am 

Joined: Thu Jan 13, 2011 10:08 am
Posts: 15
Location: Orlando
An airfield lighting series circuit is a 5,000 volt ungrounded current loop. The loop will typically have a null point with a "zero" volt reading on a proximity tester. To determine if the airfield lighting series circuit is de-energized a person must use a true RMS clamp-on ammeter.


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 Post subject: Re: Non-contact voltage test instruments ABSENCE of voltage
PostPosted: Tue Sep 20, 2022 3:34 am 
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phil.haataja wrote:
This is very interesting.......so less than 10% of the nominal voltage is considered as "voltage is absent"?


NFPA 70E are careful not to use the words "absent" of "absence" when using a non contact voltage tester.
The language NFPA 70E uses for this exception is: ttest each phase conductor.
It was an interesting discussion and I pointed out the thresholds from the IEC standard for the committee and thought it would be good to bring up here at the forum.


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 Post subject: Re: Non-contact voltage test instruments ABSENCE of voltage
PostPosted: Tue Sep 20, 2022 11:20 am 

Joined: Tue Sep 20, 2022 4:22 am
Posts: 4
Jim Phillips (brainfiller) wrote:
As part of establishing an electrically safe work condition, NFPA 70E permits the use of non-contact voltage instruments on systems above 1000 volts to test each phase conductor.
An informational note is also provided: for additional information on rating and design requirements for voltage detectors, refer to IEC 61243-1, Live Working — Voltage Detectors — Part 1: Capacitive type to be used for voltages exceeding 1kV a.c., or IEC 61243-2, Live Working — Voltage Detectors — Part 2: Resistive type to be used for voltages of 1kV to 36 kV a.c., or IEC 61243-3, Live Working — Voltage Detectors.
These standards fall under the IEC committee that I chair. According to IEC 61243-1, the presence of voltage shall not appear if the voltage to earth on the part to be tested is less than 10% of the nominal voltage. (not exactly absence of voltage)

The question:
Do you use non-contact voltage test instruments to verify ABSENCE of voltage?
Yes - with protective grounds
Yes - no grounds
No
Nothing above 1,000 volts

Your thoughts are encouraged and welcomed!

I believe the correct answer per NFPA 70E is No, for low volage systems direct-contact meters MUST be used, a non-contact could be used for initial checks but must be followed up by direct-contact. For Medium/ High Voltage, non-contact should be used.


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