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#30063 - 10/01/03 07:54 AM CAT ratings on multimeters.
Andrew Offline
Junior Member
Registered: 09/23/03
Posts: 3
Loc: Chicago, IL
I'm just getting back into industrial work and I see that Fluke keeps pushing their CAT ratings on their meters. I have an older Fluke that works just fine but doesn't seem to be CAT rated. It seems like it is some safety standard. Can anyone help me understand whether this is important or whether it's just another marketing gimmick? Are other meters CAT rated?
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#30064 - 10/01/03 08:23 AM Re: CAT ratings on multimeters.
rmiell Offline
Member
Registered: 11/09/00
Posts: 242
Loc: La Junta, Co. USA
I'm not sure, but the CAT ratings must be for the ability to interface with a computer, via one of the rated cables (CAT 3, CAT 5, CAT 6), in order to download info to a software program. If you are not doing this, then the rating is useless to you.

My opinion only.

Rick Miell
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#30065 - 10/01/03 09:00 AM Re: CAT ratings on multimeters.
ThinkGood Offline
Member
Registered: 08/07/02
Posts: 1081
Loc: Milwaukee, WI
I believe it has to do with overvoltages:
http://relays.tycoelectronics.com/lexicon/Overvoltage.stm
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#30066 - 10/01/03 09:00 AM Re: CAT ratings on multimeters.
Redsy Offline
Member
Registered: 03/28/01
Posts: 2056
Loc: Bucks County PA
The rating pertains to how close to the utility line you may be while using the meter.
I believe CAT1 being suitable for branch circuit measurement, CAT4 being suitable for measurement right at the secondary terminals of a distribution transformer.
The others, somewhere in between.


[This message has been edited by Redsy (edited 10-01-2003).]
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#30067 - 10/01/03 12:25 PM Re: CAT ratings on multimeters.
Bjarney Offline
Moderator
Registered: 04/10/02
Posts: 2527
Loc: West-Southern Inner-Northeast ...
Er, Fluke ain’t makin’ this stuff up. It’s evolved from UL Standard 61010B-1. The various “CAT” ratings are installation/overvoltage categories with Category III and IV having the highest overvoltage withstand.

One way to look at it... The higher the circuit voltage and short-circuit capability where the meter is applied, the higher the needed CAT rating. {It's nice if the meter in your hand does not vent flames or detonate in the process of checking voltage in a live panelboard.}




[This message has been edited by Bjarney (edited 10-01-2003).]
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#30068 - 10/01/03 12:36 PM Re: CAT ratings on multimeters.
Bjarney Offline
Moderator
Registered: 04/10/02
Posts: 2527
Loc: West-Southern Inner-Northeast ...
Aside — The “CAT” installation-/overvoltage-category ratings here are not the same as that for bandwidth in EIA/TIA 568 datacomm wiring.
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#30069 - 10/01/03 01:01 PM Re: CAT ratings on multimeters.
Bjarney Offline
Moderator
Registered: 04/10/02
Posts: 2527
Loc: West-Southern Inner-Northeast ...
UL’s stated objective of “1010” is to: …provide adequate protection for the OPERATOR and the surrounding area against:

- electric shock or burn;
- mechanical hazards;
- excessive temperature;
- spread of fire from the equipment; …
- liberated gases, explosion and implosion.



[http://ulstandardsinfonet.ul.com/scopes/61010B-1.html]




[This message has been edited by Bjarney (edited 10-01-2003).]
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#30070 - 10/01/03 02:02 PM Re: CAT ratings on multimeters.
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
Quote:
{It's nice if the meter in your hand does not vent flames or detonate in the process of checking voltage in a live panelboard.}


You safety minded folks take all the fun out of being an electrician.

Fireworks are beautiful any time of the year.

OK, I admit it, I have a Category III.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#30071 - 10/01/03 02:27 PM Re: CAT ratings on multimeters.
Bjarney Offline
Moderator
Registered: 04/10/02
Posts: 2527
Loc: West-Southern Inner-Northeast ...
Those miniature 250V glass fuses in some multimeters will very effectively make your ears ring during unintentional 480V “interruptions”—believe me. They may also bring rapid and unwanted attention from superiors—and not of the “atta’ boy” variety.
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#30072 - 10/01/03 02:41 PM Re: CAT ratings on multimeters.
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
Kidding aside I think we can forget that using any meters can be dangerous.

Someone I know received some serious burns on both hands from a phase rotation meter.

Apparently the 3 permanently attached leads where they entered the meter had a short in them from years of use and probably abuse (carrying it by the leads)

Now of course he should have had PPE on but this goes back to forgetting that S*** can happen even when doing the most mundane tasks.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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