20A GFCI breaker (i.e., "GFCI with overload protection" -- NOT a GFCI duplex receptacle!) seems to be tripping at low currents. Doesn't appear to be a ground fault issue but, rather, as if the "overload" was engaging too early (i.e., the breaker can be reset and "hold" in the absence of a load).
For example, plugging 1HP electric drill into circuit immediately trips the breaker (before the chuck even begins to rotate). I should try some resistive loads to see how the results differ (and, I can also get a better idea as to
*where* the trip point is -- one 100W lamp, two 100W lamps, three 100W lamps, etc.)
This particular circuit sees heavy use (e.g., 100% rated capacity) but only seasonally (e.g., holiday lighting).
All GFCI breakers are collocated in the same electric panel (which is mounted outside the house). None of the other circuits have *any* problems. E.g., 1000W hairdriers on the bathroom circuit work without a hitch; electric frying pans (two at once!) on the kitchen counter circuits have no problem.
I could swap breakers (or, equivalently, loads) and verify the problem is not related to wiring (e.g., moisture in one of the outdoor receptacles? dead bugs?)
So, question is, how is the breaker failing? What is the likely cause? Would the problem also have affected a *regular* circuit breaker (given the same sort of loading)? Or, is there something specific to GFCI breakers that makes them more temperamental?
And, how to prevent repeating this exercise, again? (GFCI breakers are pretty pricey -- and, hard to find for 30+ year old panels!)
Yeah though I suspect it's not a ground fault issue. Easy enough to check, though.
Of course, I will now regret *not* "daisy chaining" the wiring between receptacles as that would have made it easier to isolate a problem *if* that proves to be the issue (i.e., drop the last leg off the branch circuit and see what changes; then, move upstream one step and repeat; etc.)
OTOH, *if* that's the problem, it is most likely *in* a receptacle than in the actual wiring. So, I can still isolate individual receptacles from the circuit by simply disconnecting their respective pigtails...
Maybe I'll just swap the wires at the panel (different, "known good" breaker) and see if the symptoms change. If so, then I'll have the conductors "in my hands" to check out the circuit.
If it is like my christmas light circuits, it has outdoor recepticals. These seem to have a tendency to build up dirt and moisture that makes them trip the breaker pretty easily...
Reminds of last Christmas... metal reindeer, wrapped in a typical string of lamps, starting tripping the GFCI.
So I set them out in the yard with their feet in plastic cups ;-)
Then I tossed them... too much trouble to rebuild. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Sounds like ground leakage in the circuit, or a defective GFCI.
Or ground leak in the drill. Does it trip on other loads?
Swapping to another GFCI breaker is an obvious test.
You can wire through a GFCI receptacle to protect the downstream circuit. Cheaper than a GFCI breaker. A receptacle for this purpose could be installed adjacent to the panel.
I would have assumed that the GFCI would "trip" regardless of load, if that were the case (??). As it is, it will handle some *smaller* loads without a problem. Hence my thinking that it was related to the "overload" portion of the breaker.
Yes, I first noticed it with a "lighting load". Thought I was just pushing the circuit too hard. I've since noticed in when trying to use various "hand tools" on that circuit (drills, sabre saw, sawzall, radial arm saw, etc.). Of course, all of these are reactive loads so I didn't know if that was contributing to the problem.
Agreed. Esp as I have others "available" and "within reach" of the wires in the panel!
I've had bad experiences with GFCI receptacles outdoors. That's what prompted me to spend the extra money for the GFCI breaker (hoping it would be manufactured "better" than the "el cheapie" receptacles).
Why? Note the receptacles are "normal" (three wire) receptacles (the GFCI function is in the breaker).
If this is the case, then I should (possibly) be able to find some *other* receptacle on that branch circuit that doesn't exhibit the problem? E.g., one of those on the (covered) porch?
OK, this (Charlie's comment) has to be at least part of the problem.
I went to one of the porch outlets (porch is shaded; other outlets are out in the afternoon sun -- 2PM being the hotest time of day; electrical panel similarly "exposed").
Plugged in a single 100W bulb in a fixture that is always used indoors. Fine. Plugged in a second 100W bulb in another, similar fixture. Also fine. Now have exhausted both receptacles in that duplex outlet so introduce a short extension cord that terminates in a 2G box (with a pair of duplex receptacles).
Transfer both fixtures to the that "extension". All is *still* OK. (you would *expect* it to be, but... see below)
Figuring the 100W-at-a-time approach is going to quickly deplete me of fixtures, I went looking for a larger load. Electric hair dryer! Heck, it works fine on the indoor circuits so that should attest to it's "quality" (as a load).
Adding this to the 200W load blew the breaker -- before the hairdryer even got started.
[Hmmm... technically, there's a reactive component to this load for the fan motor so it's not *purely* resistive]
Repeat with *just* the hair dryer. Works OK.
Add one 100W lamp. OK.
Add second 100W lamp. NFG.
Great! I now need to quantify the load represented by the hair dryer and I know what the trip point is! (ASSUMING it is an overload trip).
Hair dryer has four settings (not counting two fan speeds). So, just switch among those settings and see at which point the breaker trips (hair dryer had been on lowest heat setting previously).
Low/cool -- OK. Warm -- OK. Hot -- OK. VERY HOT -- OK!
WTF? Surely the difference between Low and VERY HOT is more than the 200W incandescent load (that, when added to the Low setting, had caused the breaker to trip!).
Repeat the previous exercise (with the lamps). Just to be sure I didn't miss some important detail. Exactly the same results.
OK, stop "overlooking the obvious". SOMETHING is different in these two tests. What is it?
Well, to plug in the three loads (two lamps plus hair dryer), I have to resort to the receptacle multiplier represented by the "extension cord". That particular cord is often outdoors. Just like most of the duplex receptacles on that circuit!
So, while I can plug the hair dryer into the duplex receptacle ON THE PORCH and have no problems, this isn't true if the load is fed from the (three wire!) extension cord.
[I suspect if I tried plugging the hair dryer into one of the more "troublesome" outlets, it wouldn't work on the VERY HOT setting, either!]
And, this then appears NOT to be a case of overload but, rather, ground fault/leakage! But, only manifesting at larger loads? (or, perhaps only when certain outlets are utilized??)
So, what is it (?) about the receptacle's mechanical structure that can cause this sort of failure ONLY WHEN IN USE?
I will test the hair dryer on the remaining receptacles (without the "suspect" extension cord. And, possibly replace the receptacles in this 2G extension cord Jbox to see if that "fixes" the problem when using that extension cord. (This would then lend credibility to the possible solution to the original problem by simply replacing all the duplex receptacles on that branch circuit!)
It also would be consistent with my observation that the GFCI receptacles have high failure rates -- but, not because the electronics in the receptacle are failing (from exposure) but, rather, some inherent characteristic of "receptacles" themselves!
(which would reinforce my decision to opt for the GFCI breaker with "traditional"/less expensive outlets instead of pricier GFCI outlets!)
I'm assuming a "GFCI with overload protection" is the same as a device I would call a RCBO, though I still see the occasional ELB (Earth Leakage Breaker) (UK).
Is this a device that measures imbalance in the Live and Neutral current, or a device that measures the earth current in the earth conductor?
--
Mike Perkins
Video Solutions Ltd
www.videosolutions.ltd.uk
We pragmatic/parsimonious folks manage both of these (I'm pretty sure that's what bud-- is also describing.) First outlet on the circuit is a GFCI located inside (as he said, can be right next to the CB panel - perhaps not in your case if the CBP is outside), wired to protect the rest of the circuit (line is fed from panel, load goes to remainder of outlets.) The outside outlets are standard outlets, but they are protected by the GFCI feeding them, which is a less-expensive, easily replaced outlet-type GFCI, in a nice dry location. Label correctly so you can find the tripped GFCI (ideally, so someone who is NOT you can find the tripped GFCI...) when the attached outlets go dead.
Pragmatic observation - GFCIs do not last as long as breakers. So a GFCI breaker is a problem waiting to happen, and in your case, it would appear to be done waiting. Unless you are cursed with a code written by the sleazeballs that make the things, a breaker and GFCI outlet is a much better way to go, IME. Naturally, the sleazeballs do love to get their crap into codes, and they spend quite a bit of money doing so, while nobody (AFAIK) spends a lot of money keeping useless crap out of the codes.
--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.
Yes, that is what a (this side of the pond) Ground Fault Circuit Interrupter is, and Don has the variant that is combined with a circuit breaker. If line and neutral currents disagree by 5 mA (or more), the GFCI part should trip.
--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.
30 years ago we had very few RCD devices and most protection was of the ELB variety. Are you sure?
Over here the normal device trip currents are 30mA for personal shock protection and 100mA for fire protection.
5mA sounds very low and we get enough nuisance trips at 30mA! I suspect at 240V we are more likely to have more leakage.
I still suspect Don's tripping is an over sensitivity to current imbalances, though my experience is that sensitivity deteriorates with age, hence why RCDs are labelled to be tested regularly.
--
Mike Perkins
Video Solutions Ltd
www.videosolutions.ltd.uk
I am. They work on un-grounded (two prong - line and neutral, no earth/safety ground connection) devices.
Well, the "magic numbers" I learned were that 10-100ma is the range of current (through the heart) most likely to kill a person - below that the heart does not go into fibrillation and above that the heart is stopped (and will usually self-start when current is removed.) I can't say I've independently tested the veracity of that, but it was what I was taught from reasonably reliable/authoritative sources.
5mA and 25mS is the North American standard (per the not stunningly authoritative, but often correct anyway, wikipedia.) The 5mA part is certainly consistent with what I had learned independently.
--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.
- outside I think that was all that Code required.
There's no place "outside" that would ever be "nice dry locations". While we have practically *no* rainfall, when we *do* get some, it is often very hard ("driven") and heavy. E.g., not uncommon for rain to be traveling "sideways".
So, the "outside" circuit is always going to be an issue as far as locating the GFCI aspect of the protection device.
The bathrooms are obviously indoors. And, *should* be "dry" (unless you're splashing around in the sink!). You'd just have to remember which bathroom had the GFCI receptacle (I'm told putting two GFCI receptacles on a single branch circuit is sometimes problematic?)
The kitchen circuits could have been handled by nominating two outlets to be the "masters" and feeding the rest off of these. But, I didn't like the idea of having an easy way of resetting a tripped circuit there. I.e., it *shouldn't* trip and you should really want to understand why it had tripped before just reaching over and resetting it!
Curiously, none of these "indoor" circuits (breakers) have given us any problems. And, they see far more use than the "outside" circuit (though, as I stated, the outside circuit is run at ~100% of rated load at times)
See my followup post regarding today's testing. The GFCI breaker does not appear to be the problem. Rather, certain (normal) receptacles hanging off that circuit seem to irritate the condition. I'm guessing moisture and/or insects/spiders may have infiltrated these and, when in use, upset the GFCI?
I'll have to check isolation on these. Actually, I think I have such a device (or HiPot) somewhere in my mess...
Exactly. Though the "breaker" actually is a three terminal device (having a pigtail that you run off to "earth/neutral" in the panel). I suspect this is just to provide a reference that doesn't see the currents flowing through the neutral bus bar in the panel (which feeds all the other loads in the house). (?)
[I am always hesitant to dick with these things as the earthing point for that pigtail is in "mains" side of the box, beside the actual feed (before the main disconnect). Something about those big, fat conductors always intimidates me -- even though the little ones on the "breaker" side of the panel are just as deadly! Who cares if the feed is fused at 500A instead of 15-20A... you're just as dead if you slip!! :-/ ]
E.g., the test button usually shunts current *across*/around the current sense transformer -- no "earth" involved.
-----------^^^^^^^^^^^^^^^^^
While I'm sure there is *some* number that causes death if the current does NOT go through the heart (, brain or other critical organ), I've never seen a number for such a "safe" (nonlethal) current. Aside from "burning tissue", if the heart is "isolated" from the current path, is there such a figure? Or, do you just worry about burnt flesh and broken bones -- depending on the muscle groups affected?
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.