Help with Equitech 1.5Q power conditioner

OP: 

BTW, I just realized you can buy GFCI adaptors for ~ $20 from your local hardware store.   You plug one into your wall and that will let you test each device without having to move it, and certainly without having to require your conditioner. 

Here's what I mean: https://amzn.to/424lKl3

So, essentially the outlets on the back of the Equitech are wired the same way as old 240V appliances, the kind that had 3-wire cords. Correct?

That seems close, but the house N is not grounded through the Equitech. Or at least should not be. Ye olde (pre 1990s?) dryer DID bond N and ground internally to the dryer. There’s no reason to do that with a balanced conditioner... but I don’t speak for the manufacturers. Who knows what crazy things they do.

The secondary winding on these isolated devices is split. The center of the two coils is bonded to ground, so the outside ends of the 2 coils are each equal and opposite 60VAC.

And herein is a problem which the founder of Jensen transformers wrote about ages ago, that there’s still the possibility for a ground loop. Ooops.

Anyway, what floating ground load?

BTW, the output of a balanced power conditioner is not dissimilar from the 220V outlets your big appliances (range, dryer, HVAC, etc.) use.

It’s still not one +120 and one -120 V line. It’s two lines from the same transformer winding that run in opposite polarity. It is impossible to measure +120VAC. You can’t tell one from the other. The only thing you can do is measure the delta between them, which in this case would be 220VAC.

I’ve often wondered, along the same lines if the ideal situation wasn’t actually to run 220VAC to an audio room and use a combined step down and balanced output conditioner. Balanced power to balanced power essentially.

While I don't want to encourage anyone to poke around in a 220V outlet, I really don't!  I can say categorically that if you took the most advanced multimeter on earth to your dryer's 4 prong outlet you can identify 2 hot lines, but cannot identify one as being + and the other - based on the meter's readings.  Impossible.  You could at best identify 2 lines which are either  ground or neutral, and 2 lines which are energized. 

@oddiofyl - Please tell me what -60V AC means. :)

I’m familiar with balanced power and even repped one such device (ages ago). Even if that’s how they describe it, it’s not really accurate.

If you doubt me, get a multimeter, and buy an Equitech and measure it yourself.  Send me a picture of the + and - readings. :)

I believe some equipment manufacturers put a cap or sometimes a high ohm-age resistor connected from the neutral to the chassis

I haven’t seen every piece of equipment but this should not be the case for many decades. There is however often a resistor/cap between the signal ground and chassis ground, which often leads to endless fun tracking down ground loops. The resistor doesn’t cause ground loops, the ground connection, resistor or not, in the signal causes it. A place where transformer coupled inputs really shine. :)

The classic linear power supply I’m familiar with has no reason to connect the neutral to anything but the transformer primary winding but they often usually connect the center tap of the secondary to chassis ground, which is of course also often connected to the EGC. Some equipment I’ve seen does the right thing by avoiding the EGC altogether and being "double insulated." Luxman integrateds are like this, which is brilliant from a noise point of view but given what I’ve seen I’m not sure how their amps are double insulated.

@oddiofyl  -

Since it's AC, there's no + or - involved.  In a balanced outlet the meter should read 60VAC between either hot or neutral to ground, and 120VAC between H and N.

In a normal outlet H to N is 120V, H to G is 120V and N to ground is near 0.

Though we don't use signs, it's correct to say that H and N in a balanced outlet are equal and opposite at any given point in time.

It’s already at ground potential. At the service panel the service entrance neutral conductor, electrical panel metal enclosure, and all EGCs (at panel) are bonded together.

It's close to ground potential... :)  but now you have another path which is participating in that current flow.  I'd be curious to see you measure the actual current next time. :)

Anyway....

Point is, if the OP's gear trips in the kitchen the issue becomes provably to be in that piece of gear.

Reset the GFCI then checked for voltage from neutral contact to EGC, measured 1.2mV. I can’t see the math how that would cause enough of an imbalance to cause a 5ma current flow to ground.

@jea48 Couple of thoughts. I = V/R, so when R goes to 0, current goes to infinity. In this case any R less than 0.24 Ohms would result in 5mA, assuming 0 source resistance.

0.0012 V / 0.24 Ohms = 0.005 A

0.0012 V / 0.1 Ohms = 0.012 A

The other thing is that when doing so on a live home circuit you are essentially shorting the entire home’s neutral to ground.

@jea48

When the same piece of equipment is plugged into a GFCI, say in the kitchen, the small leakage ground fault will be connected to the neutral grounded conductor.

I'm afraid I don't see this yet, but I also don't want to jack the OP's thread.  Let me go think on this for a while.

Hi @jea48  - Not my first time going through a balanced power system, though it is the first time I've known about GFCI on an example.  I read through your explanation, which is what I remember.  The part that I don't get is how a GFCI, connected to the secondary windings, tripping on a balanced power system would not also trip the kitchen outlet.

As you point out, the ground is not part of the GFCI sensing strategy in either case, but it's the imbalance between the current carrying conductors (which ground should not be except on a fault) which causes the trip.

Oh, now I get it.

GFCI outlets do go bad, but it could also be equipment with a leaky capacitor to ground or a reactive load, which is most likely with bigger motors and amps.

If you find the problem is only your amp, I’d suspect swapping a GFCI won’t help.

Sometimes these trips happen intermittently, so hard to diagnose fully. Of course another alternative is to see if you can trigger any other outlet.  Maybe take the suspect piece of gear to your kitchen counter and see if you can trigger one of those outlets.

I am actually more than a little surprised that there even IS a GFCI outlet on a conditioner.  I'm not sure what the point of it is unless it's within 6' of a sink... :D

In any event, GFCI outlets are pretty standard.  If you know how to use a screwdriver you could replace it in less than 5 minutes, but I honestly have no idea what you would use it for.

Someone please explain.... :D