Cat IV

[paul renshaw]

On Cat IV meter ratings, it says service entrances..... and any outdoor circuit, e.g. overhead or underground to a detached bldg, or underground to a well. Does that include a 120V circuit to an outlet at a residence that for example goes to a post lamp or a GFCI outlet? What about a controller for a self contained pump station where all the wiring is in a cabinet? We have been having a discussion on this at work, but to me "any" means just that. Some say coach lights and flood lights are also covered under this because they are outdoors. Does anyone know of something that definitely shows a distiction between "outdoor" and other circuits? I have the Fluke tables and info from their website, but there is still a lot of discussion and opinions on this.

 

[mxslick]

In general, I interpret the CAT ratings as follows:

If a meter is rated for a given classification, then is is suitable for ANYTHING up to and including systems/circuits up to its rating. In other words, systems BELOW its rating, even if not specifically spelled out are ok for that meter.

I would think that a meter rated for service entrances would be perfectly suitable for a branch circuit, indoors or out.

 

[hillbilly1]

To my understanding, it is the available fault current that it can withstand without exploding similar to the AIC ratings of breakers and fuses, also possible higher voltages than meter is rated to temporarily to withstand. Maybe Zog has something further to say on this?

 

[paul renshaw]

I guess I should clarify more, we are wondering if the consensus is that a CAT IV is necessary to check power to a pole lamp in a yard or any 120v 1ph residential circuit. Not everyone has CAT IV meters and especially if all you do is residential work.

 

[SG-1]

As I understand CAT IV is any anything outdoor because of lightning. CAT IV also covers the service entrance because of the available fault current.

As for an outdoor outlet that is part of a residence ( wiring does not leave the structure ), I would say that falls to a CAT II or III. Even though they are outside lightning cannot roll in on them without passing through the service and the associated branch circuit.

If the outlet or lamp post is detached from the residence then you are in CAT IV territory.

I have a friend that had a meter blow out in his hand.

And don't forget the meter leads must have CAT IV rating also.