inverter doesn't like my coffee maker

[birdhouse]

The example you gave regarding plugging in the two prong plug to the ' hot ' before the neutral was contacted, that's not a circuit until both prongs made contact and there was a load.

i understand what you are saying, and the math makes sense, but in reality, this is not the case.  maybe it's because the hot is energized a bit before the neutral completes the circuit, and some inrush current trips the gfci.  i don't know. 

one thing i do know is that GFCI protected outlets that are down stream from the GFCI (especially WAY down stream) are less prone to being finickky.  why, i don't know.

adam

[Watt]

The example you gave regarding plugging in the two prong plug to the ' hot ' before the neutral was contacted, that's not a circuit until both prongs made contact and there was a load.

i understand what you are saying, and the math makes sense, but in reality, this is not the case.  maybe it's because the hot is energized a bit before the neutral completes the circuit, and some inrush current trips the gfci.  i don't know. 

one thing i do know is that GFCI protected outlets that are down stream from the GFCI (especially WAY down stream) are less prone to being finickky.  why, i don't know.

adam

Are you saying you have more than one gfci in one circuit? ( after re-reading, I think you are not saying that at all ) One more point, no argument I promise.  You say "  maybe it's because the hot is energized a bit before the neutral completes the circuit, and some inrush current trips the gfci." at what part of the cycle are you plugging it in?  When the current is ' hot ' to ' neutral ' or ' neutral ' to ' hot '?  Or, is the current not changing, at a peak? 

[rossw]

Current in a series circuit is the same through ALL that series circuit.

A core-balance or RCD type device is by its very nature quite sensitive. It has to "counteract" a substantial current in one direction with an almost exact version opposite in another wire. We're talking an imbalance of 0.03% of the full load current here.

My own experiences with "balancing" currents are that a number of conflicting events are at work.
You want multiple turns of the "sense" wire to get enough sensitivity at low currents.
Of course, you need then to have *exactly* the same for the return wire.
Stray magnetic fields from asymmetrical wiring can and do affect things.

Arcing and sparks have a high-frequency component. Transformers generally work far better at high frequencies (assuming the core is up to it), so even minute differences in layout can have far greater effects under these circumstances. Not to mention imperfections in toroidal core construction etc.

Add into the mix capacitive coupling. Long leads laying on the ground, metal-cased equipment, metal benches, metal pipes etc will all capacitively couple to the cables (even short ones). So while there may be no DC path, there *MAY* be just enough stray capacitance to get enough current to trip. Especially when a switch opens and you get a burst of HF noise.

Finally, while most ELCB/RCD/etc are made well and with suitable shielding, there's no guarantee that there won't be at least a little interference left - perhaps just enough to trip the circuit. Some of these things have moderately high gain amplifiers inside you know!

[birdhouse]

Are you saying you have more than one gfci in one circuit?

no.

i think ross sums it up nicely with why these devices are so finnicky.  although he explains it much better than i can.  i can only relate my field experiences with them. 

i guess all im getting at is there is NO way EVER with construction equipment, or coffee makers that you can instantainiaously (sp?) pull 20A from a rated 20A GFCI. 

basically, though a very good safety precaution, they're little bitche$! 

apparently my inverter has one built in, but it seems to be pretty absorbant to various things, or maybe it doesn't have one built in.  maybe it just faulted from very short dead shorts??

i don't know...  sounds like time to buy a different coffee maker!

adam

[Watt]

Are you saying you have more than one gfci in one circuit?

no.

i think ross sums it up nicely with why these devices are so finnicky.  although he explains it much better than i can.  i can only relate my field experiences with them. 

i guess all im getting at is there is NO way EVER with construction equipment, or coffee makers that you can instantainiaously (sp?) pull 20A from a rated 20A GFCI. 

basically, though a very good safety precaution, they're little bitche$! 

apparently my inverter has one built in, but it seems to be pretty absorbant to various things, or maybe it doesn't have one built in.  maybe it just faulted from very short dead shorts??

i don't know...  sounds like time to buy a different coffee maker!

adam

Go have some coffee. 

[birdhouse]

actually it's beer time!  been planning for my next visit to my ranch...  too much 16' stuff to haul.  i'm the only one of my ranchmates that can haul 16 footers, yet i've got the smallest truck!! 

hauling materials...  story of my life... 

thanks for the contributions watt!

adam

[Watt]

actually it's beer time!  been planning for my next visit to my ranch...  too much 16' stuff to haul.  i'm the only one of my ranchmates that can haul 16 footers, yet i've got the smallest truck!! 

hauling materials...  story of my life... 

thanks for the contributions watt!

adam

What are you planning to build this time Adam?  Post lots of pics.

[Watt]

Are you saying you have more than one gfci in one circuit?

no.

i think ross sums it up nicely with why these devices are so finnicky.  although he explains it much better than i can.  i can only relate my field experiences with them. 

i guess all im getting at is there is NO way EVER with construction equipment, or coffee makers that you can instantainiaously (sp?) pull 20A from a rated 20A GFCI. 

basically, though a very good safety precaution, they're little bitche$! 

apparently my inverter has one built in, but it seems to be pretty absorbant to various things, or maybe it doesn't have one built in.  maybe it just faulted from very short dead shorts??

i don't know...  sounds like time to buy a different coffee maker!

adam

Adam,

I wanted to share a bit of an experience I had with electrical distribution on a construction site once.  This dealt with one 120v gfci and a fairly large 240v compressor.  This meter setting on a pole provided that 240v split phase service to the site.  On that panel was a gfci 120v circuit with the only load device being a radio/power center type device setting on the ground which happened to be playing Mexican music as loud as can be.  While a couple of guys were doing some framing and a bit of chiseling, the compressor would cycle and when the compressor would kick on, the radio would go off and a couple of Mexican guys doing some brick work would go over the panel and cuss like I couldn't understand.  Anyway, after a bit of scratching my head I realized the earth ground rod and bonding wire at the pole had a bad connection and the compressor had a fault in the motor.  That compressor was setting on the grass but was enough to trip the circuit because some current was being returned to the mains at a nearby power pole and the other through the gfci and ground provided by the equipment ground of the radio.  Anyway, I can't comment on your GFCI experience but I bet we all have them for sure.  Those guys kept saying the other guys were turds for turning off their radio.  I thought it was funny anyway....

[birdhouse]

watt-
yea, i hear what you're saying.  and for small tools, a GFCI works fine.  the one item i own that GFCI's don't play well with is my 3hp  campbell housfield(sp?) air compressor.  (and that POS coffee maker)

my 5500w generator won't even run it, though it should.  so yea, put that beast on a gfci and forget about it ever running. 

i love working with mexican guys, because im the unusually nice GC that they never experience.  i treat them well, and they do better work because of that. 

i'm pretty picky about where my cords run AND their gauge, AND if they hit the ground at connections.  i run off homes circuits many times, and im the only one with the clients key, so i try to hammer in correct distribution of electrical needs. 

next project isn't another project, but rather finishing my roof deck. 

i'll post pictures and probably video too!

adam
 

[ChrisOlson]

A note on GFCI and how touchy they can be, and this is an easy demonstration.  Find a power tool that will run on a GFCI outlet just fine plugged directly into it.  Don't matter if it's two prong or three prong.

Now, plug in a 100 to 150 foot cord wrapped in a coil on a cord reel and plug your power tool into the cord and try to run it.  Bingo - your GFCI will trip.  Unwrap the cord off the reel and stretch it out, and the GFCI will normally not trip.
--
Chris

[oztules]

I have never found this... nor should I wish too.

Thats just too weird .......to contemplate.

I understand you have seen this to comment as you have, but I'm struggling....... just totally amazed ...... yes....amazed.

I have never seen any earth leakage device over here trigger but for leakage reasons (and sometimes I'm it).

My best guess is inductive coupling in the ext cord to ground via the spikes due to the phase switching but gee.....thats my best guess until something better comes along.



lost in space again...............oztules

[ChrisOlson]

Like adam or somebody else said, contractors have known about this for years because many of them carry their extension cords on plastic cord reels.  If a contractor shows up at a job site and there's a GFCI plug to power their tools the first thing they say to one of the grunts is, "go find a real power plug".  Or if they got a generator in the truck (most do these days) it's "get the generator out".
--
Chris

[Wolvenar]

Ok I just tried this Chris. on any GFCI in my house I could not trip any of them.. BUT just to be sure I tried this at my mothers house and bingo!

I have a bit more spendy of GFCI because of the MSW inverter, that's likely the difference.
As most of you likely know many GFCI wont like MSW at all and either buzz like crazy or trip without even anything plugged in .

One thing did come to mind last night.
Does the birdhouse's inverter have Arc fault protection as well? The thermostat in any cheap coffee pot will trip one of those.
Those things have been worse to me than any GFCI.

Its funny, electricians and politicians make up the code and laws to require these things in homes, but cannot stand then themselves.

[Watt]

Ok I just tried this Chris. on any GFCI in my house I could not trip any of them.. BUT just to be sure I tried this at my mothers house and bingo!

I have a bit more spendy of GFCI because of the MSW inverter, that's likely the difference.
As most of you likely know many GFCI wont like MSW at all and either buzz like crazy or trip without even anything plugged in .

One thing did come to mind last night.
Does the birdhouse's inverter have Arc fault protection as well? The thermostat in any cheap coffee pot will trip one of those.
Those things have been worse to me than any GFCI.

Its funny, electricians and politicians make up the code and laws to require these things in homes, but cannot stand then themselves.

Wolv, do your mom a favor and find the underlying cause of the gfci fault.  She might very well be able to thank you for your troubles some day. 

[Wolvenar]

Yeah the cause is a cheap GFCI nothing more.
There is no measurable amount of power leaking to ground from neutral.