AC Voltage tester

[ZinskI/E]

I would like to comply with NFPA 70E as well as protect myself and fellow workers when testing for live circuits. The standard is that a meter be checked against a known live source of comparable voltage, the circuit to be worked, and then against a known source again. This can be inconvenient when working in a remote or not-easily-accessible area, or can create an unsafe condition by opening gear or equipment to find an acceptable voltage against which to test a meter's operation.

I have used non-contact voltage testers for 'mushroom heads,' but would like to know if a direct contact, portable voltage generator exists for voltages from 50VAC to 480VAC. In other words, I'm looking for a small, portable, battery operated device with an adjustable AC output. The only load to be served would be a high impedance multi-meter, so power draw would be a minimum.

The device does not need to be IS. If such a tool is out there, please point me in the right direction. If not, does anyone have ideas on how to create such an implement (preferably using readily available parts!)?

 

[zog]

Biddle makes a product called a Pizeo Test, works on contact and non contact detectors. I highly recommend not ever taking it through airport security in your carry on, had a bad day doing that once

http://www.atequip.com/Biddle_Megger_DETEX _Piezo Verifier_510005_510006_512117.html

 

[richxtlc]

I hope that you were wearing your PPE for both shock and arc flash when doing this testing. The meter should be rated not only for voltage level but also for where you are testing in proximity to the utility's input. The closer you are the higher the CAT rating should be. The Biddle Piezo tester is rated for MV and HV circuits, it may work on lower voltage circuits, but you should be using a meter designed for the voltage ranges that you normally test, as stated 50 - 450 Volts.
The inconvenience of finding a place to test before and after determining absence of potential is nothing compared to being in a burn unit. Get the proper equipment and do all the necessary testing.

 

[ZinskI/E]

Rich - I completely agree that safety far outweighs an inconvenience. We are quite stringent on our PPE when testing/troubleshooting circuits within the plant, though I can't say the same for my experiences outside a safety conscious industrial setting.

An example of a recent task to illustrate my goal: a 120V circuit is supplied to a tank gauge, powering a retracting motor for the float within a pressurized vessel, approximately 100' elevated. There are neither receptacles nor lights on the elevated working platform of the vessel. To service the tank gauge, we use the motor to retract the float, block the isolation valves, de-energize the circuit, open the instrument and test for voltage. Currently to perform these steps, we climb down the vessel to check the meter, climb back up to check the instrument, climb down again to verify the meter, finally climbing back up to service the transmitter.

Now, with simple 12VDC to 120VAC power inverters available so readily and inexpensively, why should all the extra trips be necessary (not to mention the potential safety hazards of two people repeatedly climbing ladder cages fully burdened with tools, test equipment and PPE)?

The products I saw on Zog's link seem to be geared towards capacitive style, non-contact voltage testers (all very good, by the way); we use those frequently on services above 600VAC. Non-contact testers are not permitted in our refinery for less than 600VAC, hence my question.

I envision a small battery powered unit with test probe sockets (definitely not any conventional NEMA receptacle configuration) with a multi-position dial to adjust output voltage to commonly encountered values: 120, 208, 240, 277, 480. Does such a thing exist? If not, why not?

 

[zog]

I envision a small battery powered unit with test probe sockets (definitely not any conventional NEMA receptacle configuration) with a multi-position dial to adjust output voltage to commonly encountered values: 120, 208, 240, 277, 480. Does such a thing exist? If not, why not?

A Megger?

 

[ZinskI/E]

Are there AC meggers?

 

[Article 90.1]

A solution to the given example: a 100' extension cord.

 

[zog]

Are there AC meggers?

Ha, good point. Brain fart.

 

[ZinskI/E]

Article 90.1 - touche! But say the example were changed to anything besides a 120V retracting motor? Or what if, very realistically, this tank is in a tank field where receptacles are few and far between? Do you then drag a generator out and hoist the cord up for testing? It definitely could be done, but wouldn't a portable voltage generator make more sense?

 

[MikeyinLA]

How about using a small inverter plugged into the lighter in your truck?