6-32930 ZW multi Watt transformer blowing/throwing 20 amp circuit breaker

Powerhouse 180 transformers should draw around 1.5 amps each from a 120V  AC power source, for a total of about 6 amps with 4 transformers.

Is it possible that there are other loads on the same circuit breaker in your home, perhaps connected to a different outlet that are adding to the overall current draw from this breaker?

If you are sure that this one outlet is the only thing being fed by the 20 amp breaker in question, the next step in the troubleshooting process would be to use an ammeter to check the current draw by each of the 4 transformers.

While some multi-meters are capable of measuring small AC current values, most require opening the circuit and inserting the test probes in series with the live circuit.  Many less expensive multi-meters are also not designed for measuring higher values of AC current.

I would suggest using a clamp on ammeter for this task.  It will allow measuring the current flow to each device without having to expose yourself to a potentially shocking experience.  The clamp is simply placed around the transformer's power cord while it's plugged in and powered on, while the electricity is safely contained within the transformer's insulation.

A number of forum members have recommended this inexpensive meter from Harbor Freight:

Link here: Digital Clamp Meter

@SteveH posted:

Powerhouse 180 transformers should draw around 1.5 amps each from a 120V  AC power source, for a total of about 6 amps with 4 transformers.

Is it possible that there are other loads on the same circuit breaker in your home, perhaps connected to a different outlet that are adding to the overall current draw from this breaker?

If you are sure that this one outlet is the only thing being fed by the 20 amp breaker in question, the next step in the troubleshooting process would be to use an ammeter to check the current draw by each of the 4 transformers.

While some multi-meters are capable of measuring small AC current values, most require opening the circuit and inserting the test probes in series with the live circuit.  Many less expensive multi-meters are also not designed for measuring higher values of AC current.

I would suggest using a clamp on ammeter for this task.  It will allow measuring the current flow to each device without having to expose yourself to a potentially shocking experience.  The clamp is simply placed around the transformer's power cord while it's plugged in and powered on, while the electricity is safely contained within the transformer's insulation.

Thanks for the tip.  No....it's a dedicated circuit I put in specifically for this purpose and only goes to the outlet.  I've got a clamp on ammeter.  I forgot about that.  I'll give it a shot and let you know how it goes.

BTW, the PH180 current draw of 1.5 to 2 Amps should only occur when they're fully loaded and providing ~ 10 Amps @18V to the trains.  Input current draw should be very little if the transformers are working correctly and no load is connected to their outputs.

Is your 20 A breaker a standard type or a AFCI (arc-fault)/ GFCI (ground fault)?

If it is one of the latter, the problem may be in one of the bricks. I can't see 4 180w transformers tripping a 20A CB.

You are at about 1800w capacity on a 20 A circuit at 120V.

Bob

1. Measure the current with all 4 energized, if you can.

2. Swap the breaker with another 20A one.  (Like the man said, not an Arc-Fault one.)

3. Is the breaker next to another breaker that generally feels warm to the touch?

Thank you for the input and suggestions.  They are just standard Eaton Type CH single 20 amp SWD breakers.  I just swapped the breaker out for another one and the same thing is occurring.  I also tried another open position in the breaker box and it still occurred.  The neighboring breakers are not warm to the touch.  I checked the AMP draw on all 4 bricks one at a time and registered zero on all.  Just .00....It's also .00 for all four at once.  There is nothing hooked up to the bricks, so it's not drawing any amps that register, even for the little LED on light.

I think it has to be one of the four bricks....I just need to get a 5th brick to use as a process of elimination to find out what brick is causing the issue.  I can use 3 bricks with no issue. Although that's not solving the problem of what one has a surge/spike issue.

I've eliminated everything else I can think of.  Like I said, replaced the outlets with new ones, replaced the SPST on/off switch.  I cannot catch which one is causing the surge/spike to throw the circuit breaker.  Any other thoughts/suggestions?

You seem to have covered just about everything. Can you open the box where the switch is located, and by-pass it. (Take the two wires off, and connect them with a wire nut, temporarily?)  It's a long shot, but there may be an intermittent short to ground in the switch.  I will admit that I have never in 65 years of doing electrical work seen that type of fault, but...hey...ya never know.

ONLY IF you're comfortable measuring live 120VAC line voltage using a multi-meter, you may want to carefully check the line voltage (between hot and neutral) at the outlet with a load connected directly to the same outlet (no extension cord).  Something like a 1200 to 1500 Watt space heater or hair dryer plugged in to make sure the voltage at the outlet remains around 110-120 volts under load.  If it's much lower, this could indicate a poor connection somewhere that would cause a voltage drop under load.  Otherwise, it may be time to call a qualified electrician.

If the line voltage is good at the outlet with a heater connected, I'd suggest removing the heater and then re-checking the current flowing into the bricks input power cords one at at time with an output load connected to them.  I'd suggest connecting a consistent output load (like a 18 volt lights or a suitable power resistor) to each brick that will draw at least a few amps.  One of the bricks may be drawing significantly more current under load than the others.

Oh....I stated I replaced the switch, too.  I tried two other new on/off 20 amp, SPST, switches.  That's not appearing to be the cause, either.   It has to be in a brick....I just don't know how to diagnose the spike, when it occurs.  It does not show up on the ammeter when it pops the circuit breaker either.  I'm the one that posted my river project.  Now I'm finally ready to wire the power to the track and the insulated sections for the bridges.  This is just frustrating, because I'm finally ready to start wiring the track after completing my river.  I had purchased this transformer and the bricks brand new 22 years ago and never had the opportunity to use them until now.

Here was my river post I started a few months ago and completed it this week.

https://ogrforum.com/...ery-for-a-large-area

My vacation is over on Tuesday and won't be able to get back to it again for awhile.  I have a couple of ol' ZW's, but I wanted the faster circuit breaker for the newer engines I have purchased lately.  I know I can wire them with newer breaker setups.  I also have the monster ZW -L, and a Z4000, but wanted to use the bricks for running the trains.  Looks like I'll have to change how I wanted to arrange my setup until I can figure out what brick is causing the issue....bummer.

This is a long shot, but since you mentioned these are 20 year old bricks, I thought I'd throw this out. I recall that some early bricks were wired incorrectly at the factory. This has the effect of messing with the phasing.

Try this: Label each brick with a unique identifier. Then take 2 bricks and connect the grounds (commons) together. Measure the voltage across the other 2 outputs. It should be 0v, or very close to 0. If that is the case, swap out one of the bricks with another and repeat. And then do the third. If you get a 18v or higher reading, STOP! Those 2 bricks are out of phase, and that is the problem.

Chris

LVHR

@lehighline posted:

This is a long shot, but since you mentioned these are 20 year old bricks, I thought I'd throw this out. I recall that some early bricks were wired incorrectly at the factory. This has the effect of messing with the phasing.

Try this: Label each brick with a unique identifier. Then take 2 bricks and connect the grounds (commons) together. Measure the voltage across the other 2 outputs. It should be 0v, or very close to 0. If that is the case, swap out one of the bricks with another and repeat. And then do the third. If you get a 18v or higher reading, STOP! Those 2 bricks are out of phase, and that is the problem.

Chris

LVHR

I'm in the " it's the bricks" camp. My feeling is that it's an internal issue. A fault to ground in one will definitely cause the breaker to trip.

Thanks for adding this to the discussion.

I just discovered a problem relating to power strips, that have surge protectors built in (NOT GFI, but surge protection).   I had a home panel 20A circuit breaker that refused to be reset.  I replaced it.  The circuit was fine for a couple of hours, but then the same thing happened on the new panel breaker.

The electrician (and I) separately searched the internet, and discovered that power strips w/ surge protection have:

(a) possibility of a spike wrecking the power strip even if it does protect the components plugged into the strip, and;

(b) the surge protection function can break down is as few as 3 years.  When that happens, the power strip shows a ground fault which in turn can throw the panel breakers.

He replaced a second panel breaker, I replaced the 10 year old surge protective power strip, and all is good. $12 for a new one  is cheap insurance.

Summary: replace your surge protection every few years!  It may not be working any more, and when it heats up (2 hours in my case), it breaks the ground, causing a circuit breaker in the home to "break"  I have a special kind of home breakers that are combination breaker AND GFI, which is why the situation ruined two $90 20A panel breakers. 

@SteveH posted:

ONLY IF you're comfortable measuring live 120VAC line voltage using a multi-meter, you may want to carefully check the line voltage (between hot and neutral) at the outlet with a load connected directly to the same outlet (no extension cord).  Something like a 1200 to 1500 Watt space heater or hair dryer plugged in to make sure the voltage at the outlet remains around 110-120 volts under load.  If it's much lower, this could indicate a poor connection somewhere that would cause a voltage drop under load.  Otherwise, it may be time to call a qualified electrician.

If the line voltage is good at the outlet with a heater connected, I'd suggest removing the heater and then re-checking the current flowing into the bricks input power cords one at at time with an output load connected to them.  I'd suggest connecting a consistent output load (like a 18 volt lights or a suitable power resistor) to each brick that will draw at least a few amps.  One of the bricks may be drawing significantly more current under load than the others.

@SteveH  You guessed it correctly.  I believe it's in the 12 gauge wire itself that is causing the drop....perhaps it was speared by a nail or a screw when finishing the basement.  And it's just enough to occasionally cause a short when there is enough juice that is needed. Luckily I have two more dedicated 20 amp circuits in the same location, giving me 40 amps in total to use to meet my needs for the transformers.  I had 3 dedicated 20 amp circuits/outlets for a total of 60 amps. But now it's just a mere 40 amps 😉 .  Yes, I believe in overbuild...just in case.

When I plug everything into the other outlets, there are no issues or surges.   I should have tried that awhile back by plugging in the bricks to another outlet, but I thought there was nothing wrong with the 20 amp circuit until you mentioned your test  (sometimes you can't see the forest through the trees....I'm such a goof).  I have removed that circuit from the breaker box and removed the wire leading into it.  Thanks everyone for helping me narrow this down!

@Jerryc86 posted:

That's a good tip that I did not know about.  Luckily two of them are 2001  21 and two are 2002 21.  But, it is good to know if I ever buy a brick at a train show that's been used.