During a recent training class, a student shared a story that is all too common. His meter blew-up in his hand. There can be many reasons for this to happen but one of the most prevalent is measuring voltage while the test leads are in the current jacks. Because the meter has a very low internal resistance when set to measure current, the meter becomes overloaded and fails. Most meters have internal fuse protection, but this it is not something that should be relied upon for personal safety.
How to prevent your meter from blowing up
One easy way to prevent this from happening is to install barriers in, or over, the unused meter jacks. This would require the electrical technician to physically remove them in order to measure current, but prevents him or her from accidentally plugging the wrong way. This technique has proven to be highly effective in the nuclear industry. More than one reactor has been tripped off due to an improperly set volt meter.
Overly complicated equipment and policies lead to electrical hazards
I’m also a big fan or keeping things simple. Don’t provide your electrical staff with overly complicated meters. Most technicians will need a meter to perform absence of voltage checks and simple troubleshooting. Giving them a meter with a thousand functions is an error waiting to happen. Hopefully the error doesn’t result in someone getting hurt.
Last but not least, provide your staff with training. Don’t assume they know how to properly use the equipment. Stress basic meter use requirements: performing an inspection before use, using the correct test leads, ensure it’s rated for the circuit, etc. See NFPA70E 110.4(A) for additional guidance. This may be a great topic for the morning shop brief or monthly safety meeting.
Meters can and do fail. Help your electrical workers stay safe with a few small tricks.
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