Importance of CAT ratings

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dbuckley

Senior Member
Wow.

About thirty years ago I was measuring a 415V system with a non-Cat-Anything multimeter, on its 1000V range, and the multimeter went bang, though with nothing of the ferocity of this event; the meter was still physically intact. I returned it to the vendor, who asserted that I was changing the voltage range when the incident occured...

Clearly, luck was with me that day...
 

cpal

Senior Member
Location
MA
Wow.

About thirty years ago I was measuring a 415V system with a non-Cat-Anything multimeter, on its 1000V range, and the multimeter went bang, though with nothing of the ferocity of this event; the meter was still physically intact. I returned it to the vendor, who asserted that I was changing the voltage range when the incident occured...

Clearly, luck was with me that day...


luck indeed but to day with the newer energy codes distribution systems are more efficent and fault current is higher. depending on where you were in the system, the results today may have yielded a very different result.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
One of my friends is a care taker for several homes. One day he was checking voltage in a 120/240 panel and his meter blew up in his face.

When he told me about it I asked what kind of meter it was and if it had a CAT rating or not. He said it was a cheapo digital. He knew nothing of the rating. Of course, he got the usual 'don't screw with electrical stuff' lecture from me, which was probably no longer needed after this incedent.

Yes, meters DO EXPLODE!

I have also heard of decent meters exploding while checking voltages. One incedent invoved the meter being outside in the cold and getting condensation inside which provided a path for a fault.
 
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