I was cleaning up the shop and decided the best way to get rid of some electric heaters was to reinstall them in the car. (Chicago South Shore car #1 with later walkover bench seats). Here is a picture of one of them, and a close-up of the builder's plate.





Now, these are simple units. Railway Utility Co. only makes the enclosure. They contain two heater elements within. Here is one heater element and a close-up of the stamping.
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I am tickled pink to learn Chromalox is alive and well, and still catalogs this series of heater, with identical form factor, though not with these exact electrical specs. http://www.chromalox.com/productcatalog ... spx?m=3530

These heater elements are 375 watts each and entirely sealed inside a steel can, whose exterior is of course rusted after these many years, but not severely. Notice they are 67.5 volt units. It seems the Railway Utility Co. leaves it to you whether to wire the elements in series or parallel, ours are series. This gives a 135 volt package giving 750 watts at that voltage.

Sharpen the pencil... Watt's Law says at 67.5 volts, you get 375 watts at 5.5555 amps. Plug that into Ohm's Law and the resistance of each element should be 12.16 ohms. Indeed, every unit tested at exactly that. It also tested infinity across insulators, or worst case 5 megohms if the insulator was dirty.

You may notice the AC power plug on the top photo. Yes, I applied 120vac. Each enclosure contains two elements in series (24 ohms). Ohm's Law says applying 120vac should flow 5 amps... And Watt's Law says that'll give 600 watts, well within the unit's 135 volt, 750 watt rating. I ran one for an hour, and it made lovely heat without any parts getting frighteningly hot.

So does anyone else have units like this on their electric cars? Do you energize them for car heat? I am turning a thought toward wiring two enclosures in series to run on 240vac. This would allow us to preheat the car using shore power.

Robert, I am all in favor of reusing old historic equipment, but there have been some safety improvements made in the years since those were manufactured.

Most modern electrical heaters (bought at the home improvement "big box" stores) now include a "thermal cutout". This device is added so in the unlikely event the heater gets too warm the electrical power is "cutout". They are meant for situations where furniture, drapes, rugs, etc. block the flow of heat away from the heater. This can cause things to overheat and possibly start a fire.

I would like to suggest that you purchase a few inexpensive modern units (tens of dollars) and reuse the thermal cutout from them inside your historic units. It's a little (approx 1" diameter) can with a copper capillary tube that gets installed along the interior of the heater enclosure. They are simply wired in series with the heater and "open" the circuit if things get too warm.

Also, it might be a good idea to use a mega-ohmmeter to check the quality of the insulation on those units. Age is an enemy of insulation, it would be a shame if something arced over while inside a historic car.

Safest thing might be to get a modern unit and use the "guts" to modernize the "inside" of your historic units. They could still look like "period" units, but be up to date safety wise. Or, if you are only interested in cheap, safe heat just buy some modern units ?

Granted electric heaters are quite safe, but I doubt the original designers had access to modern insulators and thermal protection devices.

Just a few safety thoughts. Reusing very old electrical wiring/devices gives me pause for concern, especially 120/240 volt stuff. It does not seem like "high voltage" but it can still start a dandy fire.

While remodeling my residence I found a flush ceiling light fixture (with a burnt off "Maximum light bulb: 60 watts" label), the wiring was charred back from the fixture about a foot. Somebody had put in a 100 watt bulb sometime in the past. It was a house fire waiting to happen and I only found it because of the remodeling project. Modern light fixtures installed in insulated ceilings also include a thermal cutout device.

Cheers, Kevin.

Modern foreign stuff is cheaply built and light on materials for both resource and transportation reasons. It's designed to run hot and hard, with early failure a foregone conclusion. For instance in a Chinese heaterfan, if the fan fails the heater instantly overheats. The thermal protection is more to protect you from this design philosophy, and was not mandated until this cheap junk started washing up on our shores.

With these Railway Utility Co. heaters, I was struck by the quality of the build. The sturdy case was no surprise, but I was expecting the usual streetcar era stuff, exposed wire wrapped around cast ceramic cores. Here's what they actually are.
http://www.chromalox.com/catalog/resour ... eaters.pdf

For conduction to air, Chromalox rates this package at 8 watts per square inch, RUCo. specced it for 5 and we'd do 4. The assembly is a large unit (3 feet long) at only 750 watts. It's clear the strategy is radical overdesign: large unit, low heat output, lots of thermal conductivity, lots of surface area and tip top quality. The caging is quite good too. We haven't seen appreciable evidence of stuff falling in and blocking the elements. The units that are untouched show the occasional dust bunny and period gum wrapper which clearly date back to commuter service pre-1982.

I will check with Chromalox but I doubt the efficacy of a thermal cutout since the elements run so much cooler than the "angry chihuahua" heaters they're meant for. But it wouldn't be a problem to add one. I would also add arc-fault breakers. And yes, megger them as part of the cleaning process, though given that they are insulated for 1500, I am not expecting trouble there.

I disagree absolutely with overall stereotype that modern stuff is better, especially given the crash-dive it's taken in product quality. You might doubt 88 year old wiring, but keep in mind this car was built with the very best materials, and everything in it is insulated for 1500vdc, which most modern stuff is not. "Newer" is not necessarily an upgrade. You really have to compare on a case-by-case basis.

These heaters were removed because they physically interfered with a well meaning installation of modern "tenant grade" baseboard heaters, which didn't last 6 months. They were 2400w and weighed 10 pounds, as opposed to these heaters which are 750w and 20 pounds.

Hi Robert. Thanks for the interesting post on the heaters. I did not know that Utility used Chromalox elements. WRM stocks some strip heaters as the Key Route used them as headlight dropping resistors. Are these heaters run in series off trolley voltage as is done in so many cars? If so the safety issue with these heaters is that if a heater in the series string near the ground connection goes to ground, it may not draw enough current to blow a fuse. If the heaters are mounted to the seat frames, be sure the seats are adequately grounded so.an insulation failure will blow a fuse. OA and E did have a heater failure that energized a seat frame and killed a passenger. This is a problem since most cars have wooden floors.

If they pass, run 'em. Made today, I see them used in equipment to prevent condensation. I would -never- purchase heaters to reuse the thermal cutouts. If you have to use them purchase them as components.

If you found a stock heater rated 1200 watts at 120v that would be the same electrical specs as your heater and run fairly cool. or maybe a 1000 watt unit and it would run a bit cooler yet....

Robert, with respect, my residence was built with electric baseboard heaters in the 1960's with integral thermal cutouts. They are a wise safety feature and not related to the quality of the heater element. Mine lasted for 40 years with no failures, I only replaced them with new American made units because they had many layers of paint on them and lots of dust in them.

The thermal cutout is designed to protect the heater from it's environment, accidentally covering the heater with a rug for example. The wattage's you have are typical of residential heaters which run about 250 watts per foot.

Also I don't see the need for arc fault breakers, AFCI's are intended to protect residential outlets (bedrooms, etc) with extension cords and appliance cords plugged in. Also if you use a thermostat with old make/break mechanical contacts you should be aware that they are likely to trip often. AFCI's are not required for hardwired heaters in a residence. They are mostly meant to protect the wiring from the outlets to the loads (floor lamps, TV's, etc.). They are not used in kitchen circuits because of the larger loads (toaster ovens, etc).

You cannot run large switched loads (hundreds of watts) on an AFCI circuit breaker, it is programed to trip when the controlling contacts open up and arc. I had a refrigerator on an AFCI circuit, it tripped about once a week when it decided that the arc from the contactor inside the unit was a wiring fault.

Those old heaters are quite tough as you noted, but I would still be cautious about 80 years old wiring. The insulation can have cracks that are hidden from view.


Cheers, Kevin.

One obstacle to thermal safeties is I am not finding any rated to interrupt 600VDC. I wonder if the baseboard heaters didn't fail for the same reasons...

DC and AC protection devices are often NOT interchangeable!

Based on that alone I would use the original heaters (with new temperature rated wiring) and/or replace the elements with new in the original cans.

This is also my concern - AC arcs are much easier to quench because the sine wave nature of the current interrupts the arc with each change in polarity. A DC arc, on the other hand, can form a plasma which is extremely difficult to extinguish. Incandescent light bulbs for street railway service are built with evacuated bulbs rather than being filled with gas for this reason.

The same arcing issue can also occur with thermostats. On SN 1005 at WRM, the heaters are controlled by a thermostat. To prevent arcing, the thermostat is on a low-voltage circuit which controls a contactor which interrupts the current to the heaters.

"One obstacle to thermal safeties is I am not finding any rated to interrupt 600VDC."

Good point of course, the original post discussed running them on shore power (AC) and a later post referenced arc fault circuit breakers, so I assumed the application was for AC only.

For a DC application a contactor would be required to use a low voltage thermostat for temperature control. An AC rated thermal cutout could possibly be wired into the low voltage thermostat wiring (assuming the interrupting rating was correct of course).

Good luck, Kevin.

Yeah, that's how I'd do it. Nowhere is it written the thermal cutout must switch the load directly. It'll suffice to switch the control line to the contactor, wire them all in series. Good luck finding the bad one when it trips. Might help to wire an LED+resistor in series with each cutout.

Also these cutouts should probably be insulated for 600v/1500v. This is hard.

Found a different type of heater in South Shore #36. It's not labeled well and seems largely inferior to the Railway Utility Company. There's nothing on the chassis to say whose it is, but here's an interesting heater element.



It's not a Chromalox heating element, it's a Wiegand. It's a dead ringer for a Chromalox and intermixed with them. Here's the interesting thing. Wiegand is the founder of Chromalox.

The heaters have the exact same values as the ones I documented earlier.

This element is not made for RUCo, it's made for Vapor Corp. (who also made those caboose stoves). That tells us who makes the heater - they have no other distinguishing markings.

Just as the Wiegand elements are dead ringers for Chromalox, the Vapor Corp. heater assemblies are the same fit as the RUCo. heaters, but a different style.

Here is a Vapor heater assembly freshly powdercoated.



The heating elements installed. The elements proper were not powdercoated but got high-temp BBQ paint. The insulators were masked and carefully cleaned up.


Fully assembled, ready for burn-in. Literally. It takes 20 minutes to burn off that "new heater" smell.

Those white insulators (with the bolts through them) are (still) supplied by Chromalox for applications 480V and up, or in series, or direct heating of air - all three apply here.

The bottom iron seems complicated enough that I wonder if Vapor and RUCo didn't work together or inherit patents and tooling. I went crazy trying to find the J-hooks which clamp to the seat frames. You are seeing an original, turns out they are precisely wall clamps for 1" EMT thinwall tubing, even with the little nub on the end which makes it grab the tubing. It's obvious that this product was engineered to use those.

Those heaters are an awfully long way away from 36..

Something to keep in mind when wiring lower voltage heaters in series for use on 600 volt DC trolley power is that if a heating element or wiring cracks anywhere in the string, an arc can develop across the crack. The resistance in the remaining heaters limits the current flow through the arc so it will not blow a fuse. The result is a very small extremely hot spot that might set something on fire.

Also keep in mind that a 600 volt trolley wire will have multi-thousand volt spikes on it from inductive kick back from traction motors and other sources. (Note the recent problems BART has experienced with third rail power blowing out semi-conductors in motor control circuits.) Over about 1,000 volts a point source can develop an ionized air path to a nearby metal object that will support an arc. So even if your heaters are rated for 600 volts to ground AC or DC power, they may not be safe for trolley voltage.