jdsmith said:
I re-read the manual for the suretest but it leaves me hanging on exactly what measurement is being made and what the equipment is really doing. I did some searching and found some discussion of it in the "Exploding Lightbulbs" thread But I still don't have the whole picture. Is there an introduction available like there is for the megger?
If you read "Exploding lightbulbs", you probably wished you didn't buy the 61-165 then:grin:
Impedance testing is done online, or live. Impedance opposes electric current, like resistance, but again, online. You can't read impedance with the Resistance mode on any DMM in a live circuit, as you know.
Loop impedance testing can find you troubled conditions real quick. After you have the receps mapped out and know what is on the particular circuit in question, impedance testing can easily find troubled connections. Troubled connections equals hiring impedace/opposition, which leads to heating and possible arcing.
Say you start with the beginning of the circuit or anywhere for that matter as long as you can figure out upstream/downstream. You start at one recep and you have .23ohms on your ungrounded leg. The next one downstream, say .24omhs hot leg, next one .24ohms. The next one you see .76 ohms, you've got a problem that needs to be fixed then, like yesterday. Somewhere from your last .24 reading to the .76 through the recep, you have a bad termination, loose twist, etc., and impedance can increase over time due to several factors. Soooo, (I need to cut loose), if I had an arcing fault, legit or not, I can rule out bad connections from one reading if you know your dead end. You can test the ungrounded impedance, as well as the grounded and grounding.
People are starting to fall asleep here. Did I make that any clearer for you on why I brought up loop impedance testing after speaking of arcing RAGE?
If you are still awake, you can read this article from EC&M. Maybe I should of placed that first and just shut my mouth:grin:
http://ceenews.com/ar/electric_ac_loop_impedance/