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Multimeter CAT II Rating Discontinuation

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CosteC:
I think it makes more sense in EU than USA and UK.
USA is 120 V, so lower, safer voltages.
UK is primary single phase systems.
EU - in my flat, I have 3 phase (3x230 VAC fixed installation) electric cooker - according to FLUKE it is CAT III, despite IEC61010-1 has other opinion on this topic (FLUKE:  :-- :--) however, per IEC61010-1 installation efore my electricity meter/incomer fuses is CAT III - hence even for "home use" I may need to measure CAT III line for checking if my fuses are fine. To do it I would need CAT III 300 V meter - quite rare thing - most meters is better than this.

Per FLUKE lighting in staircase is CAT III - again, IEC 61010-1 would rather categorise it at CAT II - definition of "large building" is vague. Anyway, drawing line between Overvoltage categories is tricky.

One more thing, which may affect FLUKE, an USA company: mostly wooden small buildings in USA/UK provide little EM shielding. Buildings in EU are more often reinforced concrete and this provides some level of shielding, reducing overvoltages from lighting strikes.

Anyway, portable DMM with CAT II only makes indeed little sense, and seems to die out already. For me at least :)

bdunham7:

--- Quote from: Dr. Frank on July 24, 2023, 02:28:33 pm ---Well, I just inspected my 34465A from KS, 2015, which is rated on its front panel: CAT II (300V)
Though, it is able and allowed to measure 1000V DC... I have to check, if this is a contradiction.

--- End quote ---

Well, there you go.  Now you can't be sure whether that meter is appropriate to measure the mains in the sockets that Fungus showed! It also shows the awkwardness of putting CAT-ratings on bench meters, especially the ones with 4W resistance sense jacks rated for much less than the CAT rating on the adjacent jacks.  The only bench meter I have that I wouldn't cringe at using on mains doesn't have any CAT rating at all (due to age) and I'd be happy to see the concept of CAT go away on bench instruments. 

mendip_discovery:

--- Quote from: CosteC on July 24, 2023, 04:04:12 pm ---I think it makes more sense in EU than USA and UK.
USA is 120 V, so lower, safer voltages.
UK is primary single phase systems.
EU - in my flat, I have 3 phase (3x230 VAC fixed installation) electric cooker - according to FLUKE it is CAT III, despite IEC61010-1 has other opinion on this topic (FLUKE:  :-- :--) however, per IEC61010-1 installation efore my electricity meter/incomer fuses is CAT III - hence even for "home use" I may need to measure CAT III line for checking if my fuses are fine. To do it I would need CAT III 300 V meter - quite rare thing - most meters is better than this.

Per FLUKE lighting in staircase is CAT III - again, IEC 61010-1 would rather categorise it at CAT II - definition of "large building" is vague. Anyway, drawing line between Overvoltage categories is tricky.

One more thing, which may affect FLUKE, an USA company: mostly wooden small buildings in USA/UK provide little EM shielding. Buildings in EU are more often reinforced concrete and this provides some level of shielding, reducing overvoltages from lighting strikes.

Anyway, portable DMM with CAT II only makes indeed little sense, and seems to die out already. For me at least :)

--- End quote ---

Erm UK is mostly stone/brick. Don't lump us in with them weirdos across the pond.

The US often has two phases of 120V as they use 240V for some ovens.


In the UK most homes are single-phase, and business uses a lot of three-phase. But I know that many housing projects now are starting to go 3 phase due to the electric car market meaning there is going to be a need for more power.

bdunham7:

--- Quote from: CosteC on July 24, 2023, 04:04:12 pm ---Per FLUKE lighting in staircase is CAT III - again, IEC 61010-1 would rather categorise it at CAT II - definition of "large building" is vague. Anyway, drawing line between Overvoltage categories is tricky.

--- End quote ---

Fluke is just providing a brief description and some examples, not a detailed standard.  "Commercial lighting" in the US is often 277VAC derived from a 480VAC/3PH service panel, although you can interpret that to include a 120VAC lamp in a hotel room if you like.  Just another reason to eliminate CAT II, I guess.


--- Quote ---One more thing, which may affect FLUKE, an USA company: mostly wooden small buildings in USA/UK provide little EM shielding. Buildings in EU are more often reinforced concrete and this provides some level of shielding, reducing overvoltages from lighting strikes.

--- End quote ---

I think the bigger issue in the US would be the prevalence of local low-voltage power distribution outdoors on poles.  In theory, if lightning hit the pole behind my house, which is the highest nearby object, it could come directly into my house unimpeded other than my poor circuit breakers.

CosteC:

--- Quote from: bdunham7 on July 24, 2023, 04:37:25 pm ---
--- Quote from: CosteC on July 24, 2023, 04:04:12 pm ---Per FLUKE lighting in staircase is CAT III - again, IEC 61010-1 would rather categorise it at CAT II - definition of "large building" is vague. Anyway, drawing line between Overvoltage categories is tricky.

--- End quote ---

Fluke is just providing a brief description and some examples, not a detailed standard.  "Commercial lighting" in the US is often 277VAC derived from a 480VAC/3PH service panel, although you can interpret that to include a 120VAC lamp in a hotel room if you like.  Just another reason to eliminate CAT II, I guess.
--- End quote ---

Och. USA electric system is really confusing. 120, 240 277 480... I really prefer European 230/400 VAC, even if you add stubborn UK with its 240 VAC which anyway is the same as "continental" 230 V.


--- Quote from: bdunham7 on July 24, 2023, 04:37:25 pm ---
--- Quote from: CosteC on July 24, 2023, 04:04:12 pm ---One more thing, which may affect FLUKE, an USA company: mostly wooden small buildings in USA/UK provide little EM shielding. Buildings in EU are more often reinforced concrete and this provides some level of shielding, reducing overvoltages from lighting strikes.

--- End quote ---

I think the bigger issue in the US would be the prevalence of local low-voltage power distribution outdoors on poles.  In theory, if lightning hit the pole behind my house, which is the highest nearby object, it could come directly into my house unimpeded other than my poor circuit breakers.

--- End quote ---
You mean home panel distributes technically CAT II but as it is long and on poles it is more CAT III if not CAT IV? Anyway creating grey zone, risky installation.
My example in EU is less dangerous and more formal thing. Your example is better. I wonder how some Asia countries or Latin America see it.

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