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say a wire going to a blower motor has a cut in it running thru a package unit. it blows a fuse every once in a while. you can not figure out why the fuse blows. you whip out your extech 380260 meter. you test the blower and it shows up good. you then test each wire that feeds the motor to ground. would the extech 380260 meter pickup the crack in the wire?
I have never condemned a motor that I didnt double check with my Fluke 28 II. I think they are more of a PM tool than anything else. Maybe Im Wrong but from what I read here and from Supco's website thats how I understood it.
I don't claim to know everything but RSES membership would sure benefit a lot of guys on here.
I tend to agree with HVAClover on this one, although not as stern in my objections. A megaohmmeter is a useful tool with hermetic compressors. It is just that, a tool, among many others. I have used them as a final check before condemning a compressor. Mine is older than most of you guys. I just bought one of the Exetech analogs as my old one is tired of being bounced around in the back of the truck.
But there is no single tool or meter that will do everything for you.
In my opinion, stick to the analog meters when reading MegaOhms.
if you were to use a regular meter while trying to find the crack in the wire that fed the blower motor you wouldn't have found it. this crack in the wire was found using a megohmer. the unit would run fine for a couple months and then blow a fuse. a new fuse would be put in and it would run for a few more months and pop a fuse. i have a supco m500 and it works but sucks at the same time
Gravity- Common sense would dictate the answer to your question about a crack in the electrical wiring. Depending on where the crack is located in relation to the pinching action of the cabinet. A Carrier unit was doing exactly that with the condenser fan wires. If you megged the wires you would get a reading that would not indicate a problem. If you isolated the individual fans, there were 4 you would find a grounded lead supply power to the motor. The wire harness was pinched between 2 cabinet top sections and would only show a fault when the rest of the system was in operation.-GEO
mine has served it's purpose through the years I've had it