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A safer transformer?

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A safer transformer?
Posted by jockellis on Saturday, December 14, 2013 9:58 AM

My hair dryer died. No condolences, please. My wife quickly went out and got me another as a Christmas present because she likes to use mine and leave her hair in my sink. But a dead dryer means I have a power cord with ground fault protection.

My quesiton is can I cut this off and solder it onto the connections inside my old Lionel ZX transformer? Hair dryers typically pull 1600 watts while the transformer has, what?, 275?

Jock Ellis Cumming, GA US of A Georgia Association of Railroad Passengers

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Posted by ADCX Rob on Saturday, December 14, 2013 10:38 AM

It won't do any harm.

Rob

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Posted by M. Mitchell Marmel on Saturday, December 14, 2013 1:52 PM

Sure!  And if you use your ZX transformer while taking a bath, you're now much safer!  Devil

-MMM-

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Posted by lionelsoni on Saturday, December 14, 2013 2:37 PM

ZX?

Bob Nelson

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Posted by jockellis on Saturday, December 14, 2013 10:52 PM

Is that not the name of the early '50s dual control transformer? I can't remember. 

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Posted by TrainLarry on Saturday, December 14, 2013 11:05 PM

Sounds like it is the ZW

Larry

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Posted by ADCX Rob on Saturday, December 14, 2013 11:07 PM

Rob

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Posted by jockellis on Sunday, December 15, 2013 7:02 AM

It is definitely a ZW. I got it 60 years ago this Christmas along with an American Flyer GP-7 work train set. I replaced the cord a few years ago but these 275-watt transformers are no safer now than they were then. Lionel makes a new version of this as does MTH. I was 5 when I got it but never had any problems despite running my no. 290 4-6-2 an equivalent distance from the factory in New Haven to my house in Atlanta, GA. 

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Posted by cwburfle on Sunday, December 15, 2013 7:15 AM

What are your safety concerns?
Replacing the power cord with one that has a built-in GFI detector isn't a bad idea. In the event that your transformer develops a leak, doing so should provide some protection.
An easier alternative might be to convert your surplus GFI power cord into an extension by putting a female connector on the end, and plugging your ZW into that.

I have not seen very many leaky ZW transformers.

IMHO, the area of greater concern is short circuits. The internal ZW breaker only protects from shorts that involve the common terminals. It is very easy to accidentally create an unprotected circuit between any two "power" terminals (A, B, C, and D). All one has to do is set the controls do different voltages.
In addition, the internal breaker has a rather high trip point, and is slow to trip. The Lionel Factory test set manual gives the trip specs for a ZW as 30 amps, 11-40 seconds.
So I always recommend using external breakers, one for each power terminal in use.
There are many options for external breakers, I like to use postwar Lionel #91 adjustable electromagnetic breakers. When properly adjusted they trip instantly.

Also, NEVER leave any transformer turned on and unattended.

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Posted by jockellis on Sunday, December 15, 2013 7:15 PM

Now that's an excellent idea. I thought about replacing internally because I need to go inside and replace the roller on the right side throttle. 

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Posted by Dave632 on Monday, December 16, 2013 9:45 AM

 Never knew hair dryers had a GFI internally installed.

I must say the old ZW is sure slow to trip the breaker, mine  just runs accessories. My Z 4000 is very quick to trip.

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Posted by lionelsoni on Monday, December 16, 2013 10:34 AM

The idea of a thermal circuit breaker is that it models the temperature rise in the wiring, tripping only when the temperature has risen to a harmful or dangerous level.  The advantage to this is that loads that briefly draw high current when starting, like motors and incandescent lamps, and the occasional brief accidental short circuit, do not cause nuisance tripping of the breaker.  This is also the rationale for slow-blow fuses.

One should not rely on quick tripping to prevent damage to modern semiconductor electronics.  That stuff is killed by overvoltage, not overcurrent, and is better safeguarded by overvoltage protection--transient-voltage suppression--than by overcurrent protection.

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Posted by jockellis on Tuesday, December 17, 2013 10:18 AM
Hair dryers have cord mounted GF protectors. I was asking for info on replacing the present cord with the GF protector plug and cord I cut off my dead hair dryer. I have to go inside anyway. My concern is all I've read over the years about how they could start a fire. I've never had a problem with the slo-blo fuse. I like the idea of adding a female plug to the dryer cord. That way it will become a really useful cord.

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Posted by cwburfle on Tuesday, December 17, 2013 12:19 PM

. My concern is all I've read over the years about how they could start a fire. 

With all due respect to lionelsoni, that is where the external circuit breakers come in. As he wrote, the external breaker probably would not protect the delicate electronics that are present in many of our modern era toys. They are there to trip before wires overheat. Sure, one could use wire heavy enough to carry the 30 amps specified in the Lionel test set manual, but what about other components?
Years ago I received a rather unpleasant burn when I picked up a derailed steam engine. It had landed in such a way that it's handrail created the short.  Boy did it get hot!

I will restate my comment that the transformer should not be left unattended while plugged in.

 

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Posted by lionelsoni on Tuesday, December 17, 2013 12:39 PM

Just to be clear, I heartily endorse using individual circuit breakers on a transformer's multiple outputs, whether inside or outside of the case.  (I put mine inside, but I have made extensive changes in there anyway.)  I was addressing only the distinction between fast and slow overcurrent protection.  Neither is as good as TVSs for preventing damage to electronics, but either is safe.  I prefer slow (thermal) breakers, to avoid nuisance tripping.

These considerations are beside the point that GFI (or an equipment ground) can prevent an electrocution hazard if the transformer's isolation feature fails.

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Posted by ADCX Rob on Tuesday, December 17, 2013 2:12 PM

jockellis
... My concern is all I've read over the years about how they could start a fire...

I've never heard or seen this.  And I am a third generation fire insurance adjuster - we've never had one case like this since 1941 come through our firm.

Rob

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Posted by lionelsoni on Tuesday, December 17, 2013 7:27 PM

Never heard or seen that a fire was started by overheated wiring?  Alert the NFPA and the NEC Committee!

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Posted by lionel2986 on Tuesday, December 17, 2013 7:38 PM

Bob - I'm very interested in learning about the transformers that you use, and the extensive modification you have done. Have you posted this before?

Thanks

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Posted by lionelsoni on Tuesday, December 17, 2013 7:56 PM

I may have.  But here it is:  I use two type Z transformers.  I have added synchronous rectifiers to two of the outputs of each transformer.  These are fairly simple silicon-controlled-rectifier circuits that pass the variable secondary voltage to the output terminal when the secondary voltage is positive, in the case of one control, or negative, in the case of the other control.  Thus I can control the positive and negative half-cycles of the track voltage separately.

Each locomotive is powered through an on-board bridge rectifier which has switches in two of its legs, so that it can function as a full-wave bridge rectifier or a half-wave rectifier responding to positive half-cycles only or negative half-cycles only, or shut the locomotive off completely.  Whistle tenders have just a positive half-wave rectifier and a switch which can select normal whistle-relay operation, positive half-wave, or off.

I can run two locomotives on the same track by assigning each to one of the half-wave polarities.  I can run a steam locomotive and its whistle independently by assigning the locomotive to negative half-wave and the tender to positive half-wave, allowing me to "quill" the whistle.  And I can run everything in the conventional way on another layout by selecting full-wave for the locomotive and whistle relay for the tender.

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Posted by ADCX Rob on Tuesday, December 17, 2013 10:04 PM

lionelsoni
Never heard or seen that a fire was started by overheated wiring?  Alert the NFPA and the NEC Committee!

jockellis
Hair dryers have cord mounted GF protectors. I was asking for info on replacing the present cord with the GF protector plug and cord I cut off my dead hair dryer. I have to go inside anyway. My concern is all I've read over the years about how they could start a fire. I've never had a problem with the slo-blo fuse. I like the idea of adding a female plug to the dryer cord. That way it will become a really useful cord.

He only mentions "they" - referring to ZW transformers, which I am also referring to.  There was no mention of wires, or even wires connected to a ZW.

Rob

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Posted by lionelsoni on Wednesday, December 18, 2013 12:34 PM

I concede that not connecting a toy train transformer to any wires is a good way to reduce the risk of fire.

But, if a ZW is connected to wires in the wrong way, it can heat up those wires; and hot wires can start a fire.

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Posted by cwburfle on Wednesday, December 18, 2013 2:09 PM

But, if a ZW is connected to wires in the wrong way, it can heat up those wires; and hot wires can start a fire.

 

Which is a good reason to:

follow the manufacturer's directions
use the proper size wire
Use external circuit breakers
Unplug the transformer when it is not attended.

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Posted by jockellis on Friday, December 20, 2013 9:30 PM
I've never heard personally of a fire started by a ZW but I've read that the government was worried years ago. Now, having been a newspaperman for 25 years I know that once something is printed as fact and read by other journalists, it becomes quoted as truth many times. Have these transformers caused fires? Who knows. But I bet stupidity played a factor in it if one did occur.

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Posted by jwse30 on Saturday, December 21, 2013 7:00 AM

I'll stay out of the fire debate, but I'd like to point out that some hair dryers have GFIs that are one use only. Meaning once they open the circuit, they cannot be reset. Also If you opt to just place a female cord end and make a GFI extension cord, keep in mind that the wire in the cord is likely only rated for 4 amps or so at 120v (most hair dryers are around 500 watts, I think?) and probably not even that high for continuous use.  Your ZW is about 2 amps at 120v with a full load, so it would be fine. Your circular saw  would be about 10 amps or more and would likely burn up the cord in a fairly short time.

Hope his helps,

J White

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Posted by cwburfle on Saturday, December 21, 2013 7:37 AM

A quick look on Amazon seems to show that 1875W seems to be common for hair dryers.

Did anyone mention using a hair dryer cord's GFI with a portable circular saw?

My portable circular saw is double insulated, I think most are made that way today.
When I am using corded power tools outdoors or in damp locations, they get plugged into a GFI receptacle.
However with lithium Ion battery powered tools, its rare that I need a corded one.

Personally, I wouldn't repurpose a hair dryer cord. I'd discard it.
Like many, I used to save cords from old lamps and appliances. But I never used any. Not all that long ago I started going through my junk drawers. All those cords went out with the trash,

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Posted by lionelsoni on Saturday, December 21, 2013 12:00 PM

Ordinarily, the NEC allows an appliance to draw 80 percent of the circuit's overcurrent rating.  So most portable electric heaters are rated at 1500 watts, which is 12 amperes at 125 volts.  Hair dryers are on the other hand usually rated at 1875 watts, which is 15 amperes at 125 volts, with the somewhat controversial rationale that they are not used continuously.  If that's the rating of the discarded hair dryer, I see no problem using its GFI for a toy-train transformer (or a circular saw that uses a NEMA 1-15 or 5-15 plug).

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Posted by jockellis on Saturday, December 21, 2013 2:08 PM
As a train fan I know what the MEC is but what is the NEC? And thanks for the OK and all the information I got.

Jock Ellis Cumming, GA US of A Georgia Association of Railroad Passengers

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Posted by ADCX Rob on Saturday, December 21, 2013 4:16 PM

jockellis
...I know what the MEC is but what is the NEC?

Google is your friend:  NEC

Rob

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