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Has anyone measured the power consumption of this breaker or a similar one?

on the internet one can find horror stories of 1W+ for such breakers but no quantitative data. Data sheet does not mention power consumption.

Unfortunately I don’t have the equipment for accurate power measurement. But I just hooked it up to my Kill-A-Watt and it shows exactly 0.0 for W, Amps and VA. While Kill-A-Watt might not be perfectly accurate at low power levels, it was able to measure a smart switch (Inovelli Blue 2-in-1) at 300mW correctly.

I do not require these breakers since my existing installation is grandfathered. Yet I’d like to upgrade my breakers for safety reasons. But I absolutely do not want to have phantom power plugs. If one were really 1W, that’s 15W 24x7 in my panel and at 0.55$/kWh not negligible for me.

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  • I believe that a GFCI-only breaker does not use additional power unless there is a current imbalance. However, I also believe that AFCI functions probably do use additional power, though very little: a few thousands of a watt or less. I cannot find references to support the AFCI assertion so I’m leaving this a comment.
    – DoxyLover
    Commented Aug 25, 2023 at 12:14
  • Where are you at that charges 55 cents per kwh?
    – JACK
    Commented Aug 25, 2023 at 12:35
  • 2
    @DoxyLover You’re wrong there. A GFCI must use some power to run its monitoring circuit at all times. It should only be a very tiny fraction of a watt though.
    – nobody
    Commented Aug 25, 2023 at 13:08
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    @nobody Wow! Guess I'll quit griping about .15 / KWH here in South Florida
    – JACK
    Commented Aug 25, 2023 at 14:38
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    @crip659 they have rather detailed rules regarding what's on topic. To get to the point of it being on topic there, you'd have to get details you probably won't find without an industrial spy for the items under question here, such as the circuit diagrams. It's fairly easy to do a direct measurement of the item in question, if you understand "how to play safe with 120/240VAC while testing/measuring things"
    – Ecnerwal
    Commented Aug 25, 2023 at 15:05

1 Answer 1

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GFCI's and AFCI's (including CAFCI's) require power their detection circuits, but it's a small price to pay. Even at 55c/KWH (which is four times the US average), it costs less than $5 a year per breaker.

I measured typical GFCI 120V duplex outlets (4.9 mA = 0.59 W for 5.17 KWH per year) and a Square D HOM115CAFI combo CAFCI (7.9 mA = 0.95 W for 8.23 KWH per year).
At 55c/KWH, that's only $2.84 per year for a GFCI outlet and $4.52 per year for the CAFCI breaker. The US average is more like 71c/yr for the outlet and $1.12 for the breaker.

IMHO, it's a small price to pay for the protection of life and property. Consider:

  • Many (most?) electrical fires are caused by arcing where connections are loose or corroded. Because the high resistance is in series with the load, there is no increase in current that would trip a standard breaker.
  • Many (most?) electrocutions or other injuries from shock, such as involuntary muscle spasms causing lose of motor control, e.g., falling off an aluminum stepladder while rewiring a live ceiling outlet, occur when one's body accidentally contacts the hot (line) wire and conducts current to ground. This fault condition can be fatal at a far lower current than will trip a standard breaker (e.g., ~15 mA across the heart can cause fibrillation, about 1/1000 what is needed to trip a 15A breaker).

(I am not an electrician or electrical engineer. I have taught electrical engineering technology at the college level and have a relevant consulting practice and R&D lab.)

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    Those are prices for 1 breaker. But houses can have 10 to 30 of them. That really adds up.
    – Ariel
    Commented Sep 6, 2023 at 7:45
  • We agree the total cost is proportional to the number of breakers. But so is the value of what one is protecting, i.e., one finds more breakers in larger homes. For the average home with 20 breakers, it costs $22.40/yr. to protect $240,000 plus contents and lives. Fire alarm monitoring costs >10x that amount, HO insurance >50x, and you also have the damage, disruption, and health and life risks from the fire. That's just for arc fault breakers, GFCI combo's save even more lives.
    – MadMonty
    Commented Sep 7, 2023 at 17:18

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