It has a large Screened room that has been made a permanent part of the house. It appears that the outlets in this area are all done with metal conduit at the 'Baseboard" Level if the aluminum walls of the screen room. There are about a half dozen outlet boxes, on both the inside and outside walls of the screen room, and by supplemental external conduit, run along the lower edge of the concrete outside wall towards the front of the house. The circuit seems to have been added to the circuit that originates in the master bathroom and has a GFI protecting it on the first outlet in the bathroom. The only thing on this circuit is the two outlets in the very large bathroom, and the half dozen outlets outside in and outside the screen porch.
Here is the crazy problem. You can connect a 100 watt lamp to any or all of these outlets and the GFI will not trip. Plug anything in that has a decent load, like our portable hot tub, treadmill or even my Dremel tool running at high speed and the GFI trips instantly.
I have replaced the GFI, upgrading it to 20 Amps from 15 Amps (The breaker on the circuit is 15AMPS and never trips)
This happens if the load is on any of the outlets, including the one in the Master Bath.
I have a small plug in tester that plugs into the outlets and tells me whether they are wired correctly and if they have any shorts, etc. All of the outlets test clean.
There is one outlet on the wall of the Florida room that is on a different Circuit. Any load can be plugged in this circuit, and the load will be handled with no problems. I am not sure if this circuit is protected by a GFI.
I have inspected all the wiring and don't see any problems. HELP!!!
Pass 10A into the neutral and measure the millivolt drop from the neutral or the ground terminal to a known good ground picked up elsewhere.
This assumes the neutral and ground conductor are both #12. You should see 16 mV for every foot the outlet is distant from the panel, if the connection is at the panel where it should be.
If the spurious connection is at your end, you'd see 8mV/foot, two #12's in parallel.
To get a true 4-terminal Kelvin measurement necessary for measuring very low resistances the leads that inject the 10A should not touch the leads you use to measure the voltage. This, because sometimes contact impedance is as high as conductor resistance.
If your meter won't read that low you can use a doorbell xformer as a step-up xformer, but you'll need to measure exactly what step-up ratio you're getting in this case.
Do not connect your xformer low voltage winding across 120v unless you fuse it first! 1/16A should be about right for this application.
I would disconnect the wiring at the load side of the GFCI just as KE2KB has said, including the ground that passes through. Then on the outside outlets you will have to disconect the grounds on the outlets and the neutrals. Using the ohm setting on your meter check from neutral to ground at each, also check from neutral to the box and conduit. If you see a OL reading your good. If you get an ohm reading then I would start with that conduit. Only Do This Once You Shut Off The Power!
Does the lamp your plugging in have a ground prong?
I've only had GFIs trip without an actual fault in two instances.
1) Golf course fountain. The fountain was located about 700' from the maintenance building. They wanted a GFI breaker in the building. I advised against a breaker, use a GFI receptacle instead. The GFI breaker would trip right away, it was proved good (5 MA test), all 3 conductors were meggered at 1000 volts, less that 1 microamp of leakage. Current on the circuit with conductors capped off at the load end; 13 milliamps. Very likely due to capacitive coupling in long wires, but never proved.
2) Reflected power from distorted waveforms. Like VFDs, or any other switching-type power conversion. I don't think you can predict when this will fool the GFI, a lot of factors have to 'line up' to cause a problem. This one had me baffled until I connected current clamps from both conductors to a dual-trace oscilloscope, and found that the two waveforms didn't exactly match all the time.
Other than the above, I've always found the cause of a GFI tripping. Motor starting current, capacitor charge, transformer inrush, etc.; none of these will cause a GFI to trip without an actual fault.
So, what do you do about motor starting, etc that causes a GFCI to trip?
I'm wondering what I should do if I have to deal with this kind of issue when I install the GFCI for my washer. There has never been one before, but I have decided that I want the protection.
Electric motors are notorious for leaking a small amount of current to ground. Sometimes it's winding insulation that's failing, frequently though, it's just a build-up of dust, etc. around the start switch.
It really doesn't take much dirt inside of a motor to trip a GFI.
Sometimes, just blowing it out with air will clean it up enough, sometimes it has to be taken apart and cleaned.
I left an e-mail note to Sears about my washer, explaining that I am going to install a GFCI receptacle for it. I wanted to know whether they have any issues with that. There is nothing stated in the installation guide about not using a GFCI. The washer is only 2 years old, so hopefully it will be OK.
If it does start tripping the GFCI, I'll start complaining to Sears<g>
1 year so far with Kenmore washing machine on a GFCI in an unfinished basement and so far, knock on wood, no problems. But its good to know this info in case it does happen in the future.
That means he hasn't had any issues with it being GFCI protected.
If its a big concern to you, they do make sump pumps with a battery backup unit. Basically its a 12 volt car battery that sits in a plastic battery box and connects directly to the sump pump. In the event of a power failure (or in this case a tripped GFCI) the battery takes over.
From OP
.....The only thing on this circuit is the two outlets in the very large bathroom, and the half dozen outlets outside in and outside the screen porch.....
So 8 outlets total, with 4 in Damp or Wet locations in a highly conductive environment with lots of metal for multiple leakage paths. The GFCI is doing its job and tripping when it sees a fault current of 5ma. The GFCI can't differentiate between circuit leakage and a real fault current. The only thing it knows is to trip on the 5ma differential.
The fix may involve running a new ckt to feed the present Bath downstream load. To ascertain the leakage now you could with a suitable breakout box or equivalent to momentarily connect a resistor between AC and Grd.
I would start with a 60K resistor (2ma fault) which will will likely trip your GFCI and prove the leakage hypothesis.
If for some reason the GFCI holds then try the test with two 60K in parallel which will cause a 4 ma fault. If your GFCI still holds then I'll have to do the Hari Kari.
The way commercial El Cheapo GFCI Testers work with the GFCI Test Button is to connect an ~18K resistor between AC and ground.
The more expensive GFCI Testers can insert the leakage in steps. But even the Hubbell starts @ 1ma then can step up past 5ma with the rotary switch. Of course the actual leakage current is controlled by the line voltage. The higher the line voltage the higher the leakage.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
DIY Home Improvement Forum
3.1M posts
319.6K members
Since 2003
A forum community dedicated to Do it yourself-ers and home improvement enthusiasts. Come join the discussion about tools, projects, builds, styles, scales, reviews, accessories, classifieds, and more! Helping You to Do It Yourself!