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Permalink Reply by Scott on March 29, 2013 at 10:46am

Water, especially boiler water, isn't going to be much of an insulator.  The only time I've been fooled using my Fluke, is when I failed to notice the "K" symbol lit up.  Both elements in a steam boiler read 14.8.  One was 14.8 K ohm and the other was 14.8 ohm. 

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Permalink Reply by Brady on March 29, 2013 at 7:10pm

Hmmm... doesn't sound like a tool worth carrying if you're a guy that usually tests machines out in the wild. Glad we talked about it though.

Latté 911 said:

Hi Brady,

The difference between using the Megger versus a regular multimeter is the ability to put a high voltage across the testing points using capacitive discharge. Admittedly when there's water in the boiler a water short is usually pretty obvious, but when evaluating a machine for refurbishment that has an empty boiler and/or trips the breaker when powering up, the insulation resistance test with a Megger is quick, easy and conclusive. Cheers

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Permalink Reply by Latté 911 on March 29, 2013 at 7:29pm

Hi Brady,

I test insulation resistance using a Curtis Handyman Multitester. This is a device left over from my days working on electric forklift trucks. There are meters devoted to the purpose, and most domestic units range in the $6-800 range, though Chinese units can be found for far less which still deliver acceptable accuracy and service life. I keep it in the shop as you acknowledge, working units freshly broken-down can be usually diagnosed without one. I only take it with me when purchasing units for refurbishment. You can test a heating element, and verify integrity of motor armature and field windings, without powering-up a machine. It does have its uses. Cheers

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