When you ask Robin McFaul what the worst part about spending nine months on a small island off the coast of Alaska was, she doesn't complain about the cold or the solitude. Instead, she gripes about having to lug a cumbersome insulation tester back and forth to the jobsite. From Fall 2003 to Summer 2004, she and a handful of other electricians from Spokane, Wash.-based Peterson Electric upgraded the fire alarm systems at a U.S. military installation in the state of frozen tundra, and they had to test every wire — from point to point. “It was hard enough getting our clothes out to the island, let alone a bulky insulation tester,” she says. Unfortunately for her, the tool that could have simplified the process was still in its infancy.
Back on the mainland, engineers at Fluke's Everett, Wash., labs were developing what would later become a new line of insulation multimeters. With insulation testing becoming a frequent requirement on many new installations, and as maintenance electricians relied on it more heavily to diagnose motor problems, the team recognized a growing demand for an instrument that could perform all the functions of a standard insulation tester at a fraction of the size.
With that in mind, they set out to build a better tester, but input from electricians a little less remote than McFaul put them on the path to a concept they hadn't previously considered. What if it were possible to shrink a standard insulation tester, combine it with a full-featured digital multimeter, and still make it small enough to fit in a tool bag, they asked. The engineers mulled over that request, conducted hours of R&D, and came back with an answer.
In addition to offering digital multimeter test features like AC/DC voltage, resistance, and continuity, the 1577 and 1587 insulation multimeters provide insulation resistance testing up to 600 Mohms and 2 Gohms, respectively. The 1577 offers 500V and 1,000V output voltages, and the 1587 provides output voltages ranging from 50V to 1,000V. A remote test probe enables one-handed insulation testing via a trigger on the probe handle. Capacitive voltage is automatically discharged from the equipment under test to prevent accidental shocks. Both meters carry 600V CAT IV and 1,000V CAT III ratings.
The desire to put more test features into a smaller meter is natural, but Michael Stuart, a Fluke product manager, says it's one he's hesitant to go overboard with. The combination employed for the insulation multimeters was just right. “We could have packed many more features into this product, but it didn't make a whole lot of sense,” he says. “We went out and saw what electricians were doing, we watched how they were performing their jobs, and we watched what they needed. Anything else would have been superfluous.”
Since recently getting her hands on one of the testers, McFaul has fallen in love with it and become the envy of the other electricians on her team. Her only regret is that she didn't have it in The Last Frontier. “It's a huge deal to have all of those features in one unit,” she says. “I can't tell you how something like this would have come in handy in a situation like the one I faced in Alaska.”
Tips for Effective Insulation Testing
The right meter won't make a bit of difference if you don't know what you're doing.
Disconnect any electronic devices before testing. Apply too much voltage and you could fry things like motor drives and PLCs.
Pick the right test voltage for the insulation you're working with. Stress the insulation, but don't overdo it.
Leave the leads connected when you stop the test. The tester can discharge any residual test voltage.
Insulation testers can generate sparks and minor burns. Always use safe work practices and appropriate personal protective equipment.