I had to post some stuff regarding those misnomers of “phantom voltage” and “residual currents” on
https://www.electrical-contractor.net/ubb/Forum1/HTML/002313.html The instrument kale posted “Ideal #61-156 is a fine instrument. It costs over $300. There are several models but I would recommend at least the 61-151 model which included ground impedance tests as well as what Ideal calls “false ground” (actually a “boot leg” connection) Our OSHA inspectors use it (among others). Although the ability of the instrument to load the circuit in order to test or measure the voltage drop on the branch (more important for diagnostics for qualified electrical professionals) We (OSHA) use it for other tests. Primarily the equipment ground impedance test to insure that impedance of the equipment grounding conductor is sufficiently low enough to !. Limit the voltage to ground and provide a LOW IMPEDANCE path which will facilitate the operation of the circuit protective device (over current / breaker / fuse). From the NEC obviously. In an accident / incident / fatality investigation one has to establish many causal factors including that an enclosure could / could not become energized and the only way to establish that is to test / verify it’s ground path / effectiveness / impedance.
OSHA electrical standards courses also have students (including OSHA investigators / inspectors) testing the ground impedance on branch circuits tho establish that it’s low enough.
1.2 ohms maximum for a 20a branch, 1.6 ohms maximum for a 15a branch, and .8 ohms maximum for a 30a branch etc.
The other nice test provided by the Ideal instrument is what they call the “false ground” test. That’s the test for a “boot leg” or neutral to ground connection in the branch and as you know that connection can only be at the main service disconnect (main panel).
There is another instrument which performs the same tests as the Ideal tester. That is the Inspector II manufactured by Tasco in the Denver / Colorado Springs area. See the instrument at
http://www.professionalequipment.com/xq/ASP/ProductID.65/id.5/subID.57/qx/default.htm OSHA doesn’t endorse products but do suggest numerous (as many as we know about) hazard abatement options.
I use and train students on both these instruments.
Although these instruments are in the $300 range you could get the best pricing at
habitat for safety.com
or call them at (440) 286-5502. Tell them OSHA Professor Grizzy suggested you call and they will do right by you, and NO I don’t have any interests in this company or any of the companies or products. I’m just trying to find the best pricing for the best equipment to keep professionals safe out there.
Remember, once were beyond plugging an instrument into an outlet and are alligator clipping diagnostic equipment into circuitry we now need appropriate PPE (there that nasty word again) as prescribed in NFPA 70E, for not only electrocution protection but also burn protection for arc flash / arc blast and don’t forget eye protection.
OSHA Professor - Grizzy
