I know this has probably been addressed, but can someone please tell me what the concern is using for example original ZW or Kw transformers with modern engines that have built in electronics? What is in the newer AC transformers that make them safe?
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Circuit breakers that respond quickly. The circuit breakers in the postwar transformers don't respond fast enough.
People hate me for running my layout of Pre-War, Post War, Modern Era, TMCC and LionChief Plus off a 1949 ZW/KW combo with no added protection... but I've never had an electronics issue in over 20 years of operation.
Jon 
I’m reminded that my KW has a modern circuit breaker installed - I discovered that when I had some electrical issues, early on.
Basically it is as others have pointed out (and there have been a ton of threads on this), the old transformers were designed to protect themselves, not the units on the track. Back in the days of post war trains, that had a motor/motors, an e unit that came out of the Rube Goldberg playbook, maybe some lights, the smoke unit, and the whistle unit, a brief spike in current wouldn't likely do much damage (as I know too well, my old 671 that I look forward to recycling some day, took more than a few major shorts). The universal motor (aka the Pullmor) is a rock, literally. Modern engines, whether command control or not, have can motors that won't take surges that well, but more importantly have circuit boards with components that are relatively fragile (among other things, a static discharge can cause a chip to be fried, it is why techs working on them ground themselves), and a surge caused by a short that isn't cut off quickly can do quick work on the board. I will say they aren't as fragile as some people think, but modern equipment definitely won't take the kind of things the old post war engines did (heck, they wouldn't take the abuse kids used to heap on the engines as well, I don't think a modern unit would take well to flying off the tracks and onto the floor
.
Some say you are better off matching a modern train to a modern unit, and there is some thought to that, but a modern ZW-L is minimum 750 bucks, you can get a rebuilt ZW for around 130 or so. One thing to consider is that while the post war ZW is rated at 275 watts, that is not what it really puts out, whereas a modern transformer like the ZW-L or the MTH 4000 put out the full rating pretty much, if you have heavy duty power demands a newer transformer might work better for you.
KOOLjock1 posted:People hate me for running my layout of Pre-War, Post War, Modern Era, TMCC and LionChief Plus off a 1949 ZW/KW combo with no added protection... but I've never had an electronics issue in over 20 years of operation.
Jon
I almost hate to comment on this post because I might put the kiss of death on myself but for whatever it's worth my experience has been similar to KOOLjock1's. I use the exact same transformer combo he uses for the same amount of time and have been running trains from all eras from pre-war to modern era TMCC and Legacy engines with nary a problem, so far. The only electrical problem I have incurred was on my Christmas Carpet Central Railway a couple of years back when a minor derailment caused me to lose my MTH Tinplate Traditions PS2 256 while using that "lightning fast" MTH Z4000 Transformer. So much for its quick acting circuit breaker. All that being said I will now remove all my modern engines from my layout and return to the simplicity of post-war railroading.
bigkid posted:Basically it is as others have pointed out (and there have been a ton of threads on this), the old transformers were designed to protect themselves, not the units on the track.
Nothing has changed. This is still the case. You really should have TVS protection for over-voltage, not over-current.
It's not that transformers create spikes, they are caused rather by shorts, circuit openings, and the collapsing of current in inductive fields(transformers included). The damage is ongoing, and cumulative, with the moving trains over their mechanical connections to the track - riding the rails. You may not have a failure this year, but it will eventually happen.
The use & specification of TVS diodes is not really dependent on the type of transformer, but rather the operating voltage range of the equipment, and to select a balance/specification to allow the equipment to operate satisfactorily while clamping over-voltages at the minimum possible.
My postwar transformer (TW) did not activate the TrueBlast sounds on Williams by Bachmann engines while my modern era Lionel CW180 will. Other than that, I think pw units seem to work OK.
That raises an interesting question (with TVS), I assume then that they should be used with modern transformers if the fast blow breaker is not the only thing. Or do they have that built into their circuitry ?
Most transformers do not have the TVS. The one piece of equipment that comes standard with them is the MTH TIU, one in each channel.
Thank you gentlemen....Your comments are both thought provoking and interesting. My thoughts on all of this after reading all the comments are:
The original design of the pre and post war transformers do indeed have a potential harmful effect due to the slowness of shut down time. The procedure of replacing original circuit breakers with "fast break" devices is very helpful in protecting our new equipment. Adding external fast blow fuses makes good sense.
Most moderately priced power strips do have tvs devices which certainly do not hurt anything.
My friends at the power company tell me that power surges are by and large a thing of the past with the changes that have been in transmission line technology.
Once again thank you gentlemen, you all contribute greatly to our hobby, and it is appreciated, probably much more than you realize.
Lastly hows about some good news. Our hobby is one of dying interest.....Right? In our experience WRONG! The younger generation are not as infatuated with their computers and smart phones, because it is old hat for them. Many are really excited about the prospect of working with dad or grampa, building a railroad layout that does something that they alone created. Other example? Lego plastic blocks are selling at greater volumes then ever before....
Please keep up the great work! The Legacy you guys create will outlast us all.
TinMan3rail.com posted:Most moderately priced power strips do have tvs devices which certainly do not hurt anything.
Wrong! Most power strips have MOV devices, nothing like the TVS protection diodes we're talking about. Also, MOV devices degrade over time, every time they're called on to suppress a surge or over-voltage condition, they are degraded.
Selecting Protection Devices: TVS Diodes vs. Metal-Oxide Varistors
TinMan3rail.com posted:My friends at the power company tell me that power surges are by and large a thing of the past with the changes that have been in transmission line technology.
We'll have to agree to disagree on that point. I've seen tons of damaging surges and dropouts from the power lines.
Even assuming your "friends" at the power company are right, most of the surges we are talking about protecting the equipment from are generated right on your train layout, they have nothing to do with the power company.
This thread has been very informative, since I will soon begin to rebuild a layout. It's been a long time since I had trains running. I can't wait. Thanks again for the information.
OKHIKER posted:KOOLjock1 posted:People hate me for running my layout of Pre-War, Post War, Modern Era, TMCC and LionChief Plus off a 1949 ZW/KW combo with no added protection... but I've never had an electronics issue in over 20 years of operation.
Jon
I almost hate to comment on this post because I might put the kiss of death on myself but for whatever it's worth my experience has been similar to KOOLjock1's. I use the exact same transformer combo he uses for the same amount of time and have been running trains from all eras from pre-war to modern era TMCC and Legacy engines with nary a problem, so far. The only electrical problem I have incurred was on my Christmas Carpet Central Railway a couple of years back when a minor derailment caused me to lose my MTH Tinplate Traditions PS2 256 while using that "lightning fast" MTH Z4000 Transformer. So much for its quick acting circuit breaker. All that being said I will now remove all my modern engines from my layout and return to the simplicity of post-war railroading.
I have been doing the same thing as both gents above and have never had any issues. That being said I want to have both of my ZW’s gone thru and am considering having modern. circuit breakers installed and there is one other protection the GRJ has suggested and that is TVS. At my age I have a severe case of CRS.
On another note GRJ recommended a person that can rebuilt/inspect Postwar transformers but currently he is not accepting any more repairs and I am looking for someone on the east coast that has a good reputation for their work on Postwar transformers so anybody have any recommendations please email me my email is in my profile. Don’t really want to ship them cross country no offense to any one on this forum. One I have had since new December 1953.
RJT posted:OKHIKER posted:KOOLjock1 posted:People hate me for running my layout of Pre-War, Post War, Modern Era, TMCC and LionChief Plus off a 1949 ZW/KW combo with no added protection... but I've never had an electronics issue in over 20 years of operation.
Jon
I almost hate to comment on this post because I might put the kiss of death on myself but for whatever it's worth my experience has been similar to KOOLjock1's. I use the exact same transformer combo he uses for the same amount of time and have been running trains from all eras from pre-war to modern era TMCC and Legacy engines with nary a problem, so far. The only electrical problem I have incurred was on my Christmas Carpet Central Railway a couple of years back when a minor derailment caused me to lose my MTH Tinplate Traditions PS2 256 while using that "lightning fast" MTH Z4000 Transformer. So much for its quick acting circuit breaker. All that being said I will now remove all my modern engines from my layout and return to the simplicity of post-war railroading.
I have been doing the same thing as both gents above and have never had any issues. That being said I want to have both of my ZW’s gone thru and am considering having modern. circuit breakers installed and there is one other protection the GRJ has suggested and that is TVS. At my age I have a severe case of CRS.
On another note GRJ recommended a person that can rebuilt/inspect Postwar transformers but currently he is not accepting any more repairs and I am looking for someone on the east coast that has a good reputation for their work on Postwar transformers so anybody have any recommendations please email me my email is in my profile. Don’t really want to ship them cross country no offense to any one on this forum. One I have had since new December 1953.
I'm the second stupidest person around when it comes to electricity... finger fits well in light socket!
That being the case, I did ask the questions about the PW ZW that I have and did manage to perform maintenance on it it without electrifying myself.
1) Circuit breakers protect the power SOURCE, not the load, unless the load IS the short-circuit in which case the load is already toast. That is, whether the breaker trips quickly or slowly, if the reason for the high current flow is the electronics that is because they are cooked.
2) Solid state electronic components are harmed, cumulatively, by Transient (short, that is) Voltage events. "Fast-acting" fuses/circuit breakers don't/can't protect against this phenomena. TVS Diodes DO protect against voltage spikes. Put a TVS diode across your electronic bits and they are protected.
TVS Diode seen here across the track voltage input to the board of a PS3 SW1500:
To fully "modernize" the ZW, you need to add TVS diodes and fast acting circuit breakers externally. The TVS protects against over voltage, the breakers over current. You need both. The recommended TVS is the 1.5KE36CA.
The TVS diode protects against voltage spikes caused by collapsing electromagnetic fields generated by the layout (relays, solenoids, motors, derailments etc). This is not to be confused with household line voltage surge protectors (they have no affect on the low voltage side of things that we are concerned with here)
A short video about those spikes:
Since the source is layout side, you want the protection layout side. Many people put them on the track, others put them on the output terminals of the transformer, and some do both!
With a ZW, it is easy to take 4 TVS diodes, shape them like this so they wrap around the binding posts, (A-U, B-U, C-U, D-U).
As for circuit breakers, you can get by with 10 amp breakers from the auto parts store. There are those on the forum that have favorite models, seek exceptionally fast trip times, or dial the breaker rating for their load rather than the supply (nothing wrong with all that, just makes things more complicated than they sometimes need to be).
You should also be made aware that you can use solid state diodes (1N1190AR) to replace the copper disc rectifiers, but you can cross that bridge if/when you need.
@Tranz4mr has great advise and tutorials on restoring ZWs on his webpage. http://www.tranz4mr.com/ZW_Page.html Each picture opens a tutorial.
This is the one I use: 1500W 33.3V TVS at Digikey
Quick question on the diodes. Is there a + and - alignment, and if so, how does one tell? The picture above doesn’t appear to give any indication.
Bob Golfs posted:... Is there a + and - alignment, and if so, how does one tell?
The un-banded diodes are bi-directional, there is no polarity.
Clearly, since you're connecting them across the AC, there should be no polarity. 
Fuses are fast, but It can be a pain to keep replacing them especially if you don’t find the short right away. For that reason, some people don’t like them.
I use 10 amp mini fuses on my track loops (I don’t want to replace the 20 amp fuses in the TIU). I also use magnetic hydraulic breakers (one for each track loop). I had 10 amp Snapak breakers, but the fuses almost always beat them. I recently installed Eaton FAZ B breakers (some 3 amp, some 4 amp). The 3 amp breaker beat the fuse 2 out of 2 times so far. I’m pretty sure these fuses won’t trip during normal operation, but I haven’t really put a heavy load on them yet. I also have a number of TVS diodes installed around the layout.
Question: Would it be useful to solder these diodes between the middle and running rails of the track every five or six feet?
I'm glad this topic exists.
I'm in the middle of replacing the circuit breakers on my older postwar Lionel transformers with new ones designed for them (ZW & KW). Henning's Trains and other stores seem to have these pieces readily available at very affordable prices.
The diodes thing is new to me, but definitely something to keep in mind, especially when I build a permanent (non-carpet) layout.
Mikado 4501 posted:I'm glad this topic exists.
I'm in the middle of replacing the circuit breakers on my older postwar Lionel transformers with new ones designed for them (ZW & KW). Henning's Trains and other stores seem to have these pieces readily available at very affordable prices.
The diodes thing is new to me, but definitely something to keep in mind, especially when I build a permanent (non-carpet) layout.
The replacement breaker still isn't fast enough for modern trains. You'll need either an external magnetic breaker or fast blow fuses. You can install the diodes even on your carpet layout no problem.
OKHIKER: Your short that fried your PS2 board likely was an INTERNAL short across the derailed engine truck which even low voltage transformer output surge protection and fast acting Z4000 breakers could NOT have prevented. Only an INTERNAL electronics circuit interrupter could have tripped and saved your board, but then would have had to be reset or replaced.
The diodes seem to be the easy answer to the two-piece problem, and don't cost too much. I'll likely pick up a few the next time I hit my local electronics retail store.
Thanks for this thread. Yes, it repeats, but this is a subject worth bringing up often. Thanks to many of the "usual suspects" like Rob and GRJ for continuing to educate Luddites like me.
One point raised on one of my similar threads is that modern transformers have more output wattage. I'm building a new layout and own a plethora of PW transformers rated in the 90W - 120W range (RW, LW, 1033, TW). I bought a PW ZW which I'm trying to reserve for the annual Christmas setup.
On a long loop, I'm concerned that a single PW transformer won't have enough juice to run two trains on the same mainline. Probably won't which means I need to break each mainline into two power blocks and take up two channels on a TIU or use two powermasters. A single 180W "brick" would likely do the job of two PW transformers, so there is that to consider.
I'm probably going to use my PW transformers anyway, but wanted to let GRJ know I hear him.
One thing to remember if it hasn't been mentioned already. TVS don't last forever and there's no way to tell if they're damaged by a voltage spike.. Not easily anyways. Best to change them every so often!
Lou1985 posted:The replacement breaker still isn't fast enough for modern trains.
There is NO breaker or fuse fast enough for protection of modern train circuits. You want over-voltage protection, not over-current protection(which is fine to have to protect the transformer & wiring).
Tinplate Art posted:OKHIKER: Your short that fried your PS2 board likely was an INTERNAL short across the derailed engine truck which even low voltage transformer output surge protection and fast acting Z4000 breakers could NOT have prevented. Only an INTERNAL electronics circuit interrupter could have tripped and saved your board, but then would have had to be reset or replaced.
This is the issue.
WHY NOT?
FWIW about the cost(s) of modern MTH and Lionel transformers...I run TMCC and Legacy off of two Lionel 180 watt bricks. I've seen them trip PDQ whenever there is a derail, or mishap. The two 180 watt bricks suffice for 4 engines and passenger cars, and WAAY less $$$ than a modern ZW or large MTH transformer.
With the exterior plates grounded, you are just increasing the chance of a 120 volt potential floating around the trains and layout. The Lionel transformers are supposed to be isolated from the mains, and as you have no control over the other appliances in the area or the integrity of the household wiring and any extension cords used, you're making them go live.
When i replace a cord on a 1033, I use 3 conductor 12 AWG rubber cord with three prong plug. I ground the bottom plate to the green wire on the cord. this prevents a shock if anything should occur in the transformer case. the unit should be attached to an arc flash or GFI outlet for additional protection.
I have a question. I use the early MTH Z4000 transformer, does it have fast breakers? Thanks Don
What I’m getting from this, is that some TVS diodes would be a quick fit and a value buy.
My K Line Hudson has derailed and shorted several times, tripping the transformer and it doesn’t seem to have affected the board. The PE Berkshire seems to be holding up ok, too.
Rockershovel posted:...K Line Hudson has derailed and shorted several times, tripping the transformer and it doesn’t seem to have affected the board. The PE Berkshire seems to be holding up ok, too.
The damage is cumulative.
I think you guys are talking electronics within the train-
My problem was an old American Flyer transformer, a 22080 and I bought DALLEE whistle and controller for my postwar. I bought 2. Both were wired correctly. Both fried before they got 1/2 way around the track. I later read that the new electronics don't "like" some old transformers.
Boy did Dallee give me a terrible time when returning withing the 14 day grace period. never again.
DOUGB
If you use 3 wire plugs with ground wires with train transformers you may have issues phasing two or more transformers on layouts requiring several transformers.
Charlie
You basically have two choices if you want to turn your postwar transformer into a modern one.
Lionel's TMCC Lock ON will essentially turn the transformer into a Lionel brick. Fixed voltage suitable for command control engines.
A DCC specialties psx1-ac will turn it into a full voltage range modern transformer. Both will trip in less than 10ms. Add some TVS's to complete the setup.
Pete
I disagree on the comment on the three pole plug, I use a power strip and when I put the three conductor on the transformer I check the power side is the same location on the transformers. There should be no problem as the power is the same polarity using a outlet on one side of the breaker. the problem is when you use two outlets on different sides of the breaker box. Then phasing will not work and you got a problem.
DougB posted:I disagree on the comment on the three pole plug, I use a power strip and when I put the three conductor on the transformer I check the power side is the same location on the transformers...
There is no problem with using a three pronged grounding plug for the way you are using it. The problem comes up when the grounding plug wire is connected to a metal part of the transformer - a big no-no. Just cut it and leave it not touching anything.
ADCX Rob posted:DougB posted:I disagree on the comment on the three pole plug, I use a power strip and when I put the three conductor on the transformer I check the power side is the same location on the transformers...
There is no problem with using a three pronged grounding plug for the way you are using it. The problem comes up when the grounding plug wire is connected to a metal part of the transformer - a big no-no. Just cut it and leave it not touching anything.
I disagree - a polarized plug could be utilized for the same purpose and NOT give the false impression of grounding. I'll concede for a home user who did it them self, "whatever". A true professional would never ever consider that as acceptable.
I disagree, something goes wrong in the transformer, the metal plate on the bottom could get charged, if grounded by the three conductor the charge would go to ground kicking off the breaker and the user would not be in danger . Remember the PW transformers are not double insulated as are the new transformers are. Is the new MTH and lionel transformers three plug? Remember the PW transformers did not have a UL sticker and this indicates why.
DougB posted:I disagree, something goes wrong in the transformer, the metal plate on the bottom could get charged, if grounded by the three conductor the charge would go to ground kicking off the breaker and the user would not be in danger . Remember the PW transformers are not double insulated as are the new transformers are. Is the new MTH and lionel transformers three plug? Remember the PW transformers did not have a UL sticker and this indicates why.
Classic transformers not UL listed? Guess you haven't seen a few:
I could be wrong, but I recall hearing that some of the more powerful PW transformers couldn’t get a UL tag not because of the plug or double grounding, but because they put out too much power. I just looked at my Z and one of my ZWs. Neither one had a UL tag.
You are correct on the UL sticker. Never the less, I like to ground all electrical devices. I always put a seperate ground on washing machine or dryer. Many years ago I noticed that the washing machine gave off a tingle when I put the clothes on it, I dismissed it as static electric. So I put a ground to a water pipe, what I got was one **** of a spark. What had happened in the fuse box was that the clamp on it wore through the main wire insulation and made the box hot, thus power touches the ground but since there was no CB or fuse between that and the meter pan, power ran through the ground to all appliances. Needless to say, I replaced all from the pothead to the new circuit breaker box. Later I got the power company to change the wire to the pole from AL to 2 AWG copper , replace the rotted pole and replaced the transformer.
Lehigh74 posted:I could be wrong, but I recall hearing that some of the more powerful PW transformers couldn’t get a UL tag not because of the plug or double grounding, but because they put out too much power. I just looked at my Z and one of my ZWs. Neither one had a UL tag.
I have the same understanding. The VW (same design as the ZW) was UL listed at 150W, but the ZW, despite exactly the same in terms of isolation and construction, was not because it was "too powerful" for "toys"
One more comment on the UL sticker, codes change, what was ok then may not be code now, for example the electric dryer was a three wire connection, now its , Hot,Hot, neutral and ground. The old transformers did not have a polarized plug, now we see such on double insulated tools. A GFI does not need a ground to work, as it measures the power in vs the power to the neutral if not the same which would indicate a leak of power and shut off. As a construction safety manager I can not tell you how many times I have been given a GFI and the worker says the gfi does not work, gee the GFI found a leak and shut down the unit. then an investigation on the problem occurs, most times its a defective extension cord. when the PW transformers were sold we did not have GFI and Arc fault outlets or breakers, just look at the fuse boxes with round glass fuses against the Circuit breaker boxes today. House fires dropped significantly since we stopped using 14 AWG in houses or knob and tube type distrubition systems or fabric wrapped wires, which the rodents ate and caused fires.
Maybe OGR could get a registered professional engineer, will expertise in the NEC, to write an article to address all the concerns above?
Cute UL stickers from what the 1960's or earlier. UL today is far more advanced in electronics certification than it was 60 or 70 years ago.
Back then they used methods applicable to the THEN electronics. If you are counting on your grand-daddy's certifications good luck!
All this talk of "UL" listings aside...getting back to the original question.
I have been running my "electronic" - equipped locos with an MRC 027 "Dual Power" unit; much newer than "old style lionel transformers". It runs them just fine.
I did try an American Flyer 15B with the same steam engines, just to see how they would perform. The speed control was not as precise, but they did put out more smoke...I'm guessing the 15B's minimum voltage is higher than that of the MRC unit, so the smoke resistor heats up quicker(?)
Mark in Oregon
Just glad I have a modern UL certified Z-4000! (WINK) I have a Monster theatre quality surge device on the input side and either a Scott's Odds and Ends surge device OR a QSI Power Guard on the output side. Works for me. Also since my electric service installed a voltage regulator on my power pole, I rarely have to change any type of lightbulb.
Tinplate Art posted:Just glad I have a modern UL certified Z-4000! (WINK) I have a Monster theatre quality surge device on the input side and either a Scott's Odds and Ends surge device OR a QSI Power Guard on the output side. Works for me. Also since my electric service installed a voltage regulator on my power pole, I rarely have to change any type of lightbulb.
FYI the QSI Power Guard uses TVS's with some LEDs to indicate spikes. They were ahead of the curve long before TVS's became the talk of OGR. The main consequence of UL today is the 10 amp limit per channel on transformer outputs.
Pete
I have never reached the 10 amp limit on the two throttles. 3.5 on each one max with two traditional standard gauge locos, one a 400E and the other a 408E.
KOOLjock1 posted:People hate me for running my layout of Pre-War, Post War, Modern Era, TMCC and LionChief Plus off a 1949 ZW/KW combo with no added protection... but I've never had an electronics issue in over 20 years of operation.
Jon
Same here... run all my stuff old and new off of my trusty ZW’s with no added protection as well. Try to be quick with the handle if anything does happen, but have had no problems in doing so.
ADCX Rob posted:DougB posted:I disagree on the comment on the three pole plug, I use a power strip and when I put the three conductor on the transformer I check the power side is the same location on the transformers...
There is no problem with using a three pronged grounding plug for the way you are using it. The problem comes up when the grounding plug wire is connected to a metal part of the transformer - a big no-no. Just cut it and leave it not touching anything.
I know I said that the subject is closed as far as I was concerned, but I have been advised to state as a final comment that the practice of installing 3 wire cords with 3 prong cords on the older transformers is correct. The facts are that if the transformer is in good shape it is not necessary. In the rare case that there is a short inside the transformer that makes its way to the transformer mounting plates, it will energize the base plates with power. It may only be a small voltage, but it could also be 110 volts. The grounding of the plates, will short out small voltages to ground, and in the case of a large voltage, it should blow the house breaker. It is for this reason that every appliance, tool etc that has exposed metal will have 3 wire grounding cords.
People use these transformers in all kinds of environments, from nice dry living rooms to damp basements some with water on the floor, some outside. If our practice saves just one life, the investment we have made is well worth it. I strongly encourage everyone who is changing a power cord on their transformer to follow suit and use a 3 wire cable. The procedure I suggest is wire the black and white wires first, then plug the transformer in and scratch the green wire on the outside plate of the transformer. If there is any spark at all, I strongly advise you to scrap the transformer, which is exactly what we do. We have followed this procedure for over 200 transformers since we started this procedure and have not received one complaint of the transformer not operating perfectly or anyone getting a shock. How do I know of this number? Because we purchase our cords in 100 lot quantities, and we are in our third batch. I will not respond further on this issue. My intent is solely to do what little I can to help provide a safe train environment. If that is upsetting to some people so be it. Please consider our suggestion when you are replacing cords. If you have someone else doing this for you, ask them to do the same test. Thank you all for your patience.
TinMan
Thank You for taking the time to reply, I agree with you. Our club is getting rid of old transformers, I advised since they are in poor condition they could be a liability if we sold them or gave them away. That being said the three wire cord is the only way to go. I also agree with the method of testing the transformer with the ground wire.. Thank you for your educated reply.
TinMan3rail posted:The procedure I suggest is wire the black and white wires first, then plug the transformer in and scratch the green wire on the outside plate of the transformer. If there is any spark at all, I strongly advise you to scrap the transformer
This right there says all you need to know - a true professional would not recommend nor boast about performing a continuity test in such a fashion at line voltage. As such, recommend that others, as I, to treat any recommendations or conclusions as suspect.
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