Can anyone point me to a code/standard/recommended procedure of adding AC circuits to railroad equipment? I'm not particularly interested in Amtrak Head End power wiring, but more the situation where permanent wiring, outlets, lights, etc are added to a car that is in periodic service and is connected to ground power through some sort of plug. Am particularly interested in grounding methods, neutral bonding, etc. Am also interested any recommended plugs/outlets used for more than 120v, 15 amp service.

Greg

From the 2008 National Electric Code:

Article 90.2 Section B Part 1

NOT COVERED:
"Installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles."

In other words the NEC has no set rules for running power in a railroad car. So go nuts I guess.

-On a side note when it comes to grounding in these situations I always grounded back to the outlet I plugged into AND ran a few self tapping screws with bonding jumpers run to them into the frame of the car. That juice will make it too earth one way or another:)

What I've seen done is to use dryer plugs and receptacles. One car is equipped with a generator putting out single phase 220v (two 120v hots and a neutral, same as you'd have coming into your house) On the end of each car you'd have dryer receptacles, and the cars are jumpered together with a piece of SO 6/3 or 6/4 and a male dryer plug on each end. Each car has a breaker panel to distribute power to lights, PA amplifiers, etc. Then for ground power, you just have a service disconnect on the wayside fed from your station/shop/etc. feeding another dryer receptacle, and you'd simply disconnect the generator and hook a jumper to the end of the train - or on your generator car, you could have the cars electric tie into the generator underneath with a cable, dryer plug & receptacle, and the cable would be long enough to reach your wayside disconnect.

The thing I don't like about this arrangement is the inherent safety risk of having exposed conductors that might be energized with the male-to-male jumper setup. However, the HEP type cables and their connectors are prohibitively expensive, and really designed for 480V 3 phase delta HEP. Really overkill for a tourist road with 1920's open window coaches whose only requirements are lights. Ideally, restoring the coaches to their original axle-driven/battery operated 32VDC system would be awesome, but wouldn't work on a 15mph scenic railroad.

I've wondered what other tourist roads with this type of rolling stock have done. Ideally the connector would be a friction-fit device (for the errant conductor that forgets to disconnect them) that could have female-female jumpers, and a hinged lid on the car end to cover the exposed male conductors. Having been in the theatre/live music lighting business for several years, I might have proposed using 60A stage pin connectors. But I'd really like to know what the rest of the industry does.

480V 3 phase delta HEP

I understand 480 volts, three phase, but what does "delta", mean?

this site may help a bit http://www.allaboutcircuits.com/vol_2/chpt_10/5.html

Hello Greg,
May I suggest looking at the electrical fittings used on motor homes and boats for shore power inlet. These are mounted in rain tight enclosures.. A larger motor home supplier should have some in stock to look at. These fittings are not too expensive.
Karel

New Hope & Ivyland RR back long before 1990 determined that the 32 volt Direct Current system in their ex-Reading RR coaches was insulated for at least 120 volts. So. they connected a 120 volt Alternating Current generator mounted under the coach converted to a "dining car" to the socket where station or layover power would be connected. Adjacent cars were connected with the same male emergency jumper cords and female sockets under the roofs used back in 32 volt days. Light bulbs were changed to regular household or shop type, and the air conditioned cars were taken out of service or converted to open air cars.

I don't imagine they make those type of connectors and receptacles anymore. I wonder if there's a drawing for them somewhere? Any pictures of those jumpers? The CNJ coaches used the same thing, but theirs connected below near the brake, signal, and steam heat connections.

The power jumper connectors used on coaches were simple enough that they could be shop made, but would be tremendous overkill, so there would be no sense making them unless one were trying to use the existing jumper receptacles on the cars. Remember, since 32V is only about 1/4 of 120V, they had to be designed to carry 4X the current, and were expected to carry the entire load, including a/c blowers and the like.

The closest commercially available connector I can think of is a electric forklift battery connector. go to:

http://www.grainger.com

And search on part number 3BY20. That should get you Grainger's listing. For more technical specs, go to:

http://www.andersonpower.com/products

And search on part number 6319. This is the same part Grainger sells. Ratings are 600V 50A, different sizes are made to accept wire from 6AWG to 2/0; the #6 should be adequate for a 50 amp system.



Note these are "dead front" plugs, that is the live conductors are recessed inside the housing. The same plug mates with itself, one needs to be turned 180* to the other. The housing has holes to bolt the stationary end to the car. One problem I see is no ground conductor, however, with all cars sitting on conductive rail, simply grounding each to the car frame should suffice. The "shore power" station should be bonded to the rail.

The way Amtrak does it with HEP, they have a 6-pin connector. Three of the terminals are quite heavy, and carry 480VAC three-phase in "delta" configuration. The other three pins are signal lines. One of the pins is shorter than the others.

The short pin is trainlined separate from the other pins. Typically, HEP wiring uses four parallel connections between each car. Each connection is the 6-wire plug I describe. This is for redundancy - added current capacity. The power wires are tied together inside each car. However, the short pin signal wire is not tied together, and is trainlined independently. On the last car, each pair of connectors is looped back to itself. This results in the "short pin" making a continuous loop (or two) down the entire train and back, assuming all cables are plugged and seated.

The generator energizes that wire on one connectors, and looks to see the signal come back on the other connector. Then it knows all connections are complete and seated, and no connector is flopping loose, waiting to expose 480VAC to curious fingers.

I would further venture to say there are three things you definitely don't want to do. And when you overlap all three things, you will be sitting there going "How do I wire AT ALL?" There's an answer.

#1 - don't use the rails as a current return. Why? Rusty rails. If the car loses solid electrical contact with the track, or if inter-rail bonding isn't tip-top, you will energize the steel body of the car, and create a shock hazard for anyoneon the ground or between cars.

For instance, in a house, you have 2 "hots" and a "neutral", there is 220VAC between the hots, and 110VAC between either hot and a neutral. Electrical code says tie neutral to ground at the main service box. So, imagine we get someone "clever" who says "I only need to trainline the two hots since neutral equals ground". When someone plugs in a 110VAC appliance into the second car down from the generator, the current return is via neutral, i.e. via the track.

Also, if it's not an electric railway car, there's no provision to flow current through the bearings, and this will cause arcing, pitting the bearings and maybe setting a journal on fire. If it is an electric railway car, you have a much worse problem.

#2. Now that you've wired your neutral, don't use the rails as ground either. Why? Because if a rusty-rails situation intersects with a ground-fault situation, then again you have energized the sides of the car and created shock hazard.

#3. Things REALLY get hairy on an electric trolley operation. You need to really think through what you are doing, and you may need to get a restraining order against the local terrestrial electrical inspector, who will want you to do the BadThing. Here is why. Imagine your train is tootling along, with the motor (car with traction motors) in full parallel, slurping 600 amps off the trolley wire and returning it through the rails. Suddenly the motor hits a "rusty rail" situation and loses ground. It's going to try to find ground any which way it can. The other cars in the train still have good ground, and it'll try to find ground through them, and any wiring between them. If you've trainlined ground, it will attempt to pull the 600 amps through that. What gauge wire did you say you used? :)

The astute student of electric traction will have noticed this. They NEVER trainline ground, for just this reason. You see auxiliary power jumpers for lighting heat and the like, but even if the connector has two pins, it only carries trolley voltage. Return is through the rails. If the trailer loses ground, the lights go out. You look at the various MU control schemes. Westinghouse HL (line powered) has many signal lines but no ground in the trainline. Westinghouse HB (battery powered) has both battery + and - in the cable (when motoring), but the entire battery system is isolated from chassis. This problem has been accounted for, with great care.

I presume the forklift battery connector idea was for trainlining 32 or other low voltage because although the connector may be rated for higher voltage those contacts are accessible to fingers not to mention lack of separate ground.

The marine shore power connectors have the same issue using dryer or range plugs do in that there would be exposed contacts if using jumper cables although I like the idea that they are more suited for outdoor wet locations.

I think the simplest thing is to hardwire the jumper to the front of the car with an enclosure to coil it up and store it if not in use. The rear ends of cars have a fixed connector to plug these into. Connections could be range or dryer plugs or the marine shore power devices. This presumes cars always face the same way and are fed power from the front. In the event there is an unusual need to operate in another way with power on some special jumpers or adapters could be arranged. That could leave a live dangling male at the end; maybe the boxes the fixed jumper are stored in could have a dummy female.

Another idea would be to replicate the safety circuit of real HEP. Note that modern code-compliant range & dryer plugs now have 4-pins: Hot, Hot, Neutral, Ground.

(The older type, no longer allowed in new installations, lacked a separate ground. The appliance frame was "grounded" to neutral. That was potentially dangerous because most equipment contained some devices that were 120V and connected from one hot to the neutral. If the neutral connection was somehow lost the frame would become hot at 120V. Thus the newer type have a separate, legitimate ground.)

You could use the ground pin for a low voltage trainline complete signal. Cars are fitted with female range or dryer receptacles at both ends and jumpers are male/male. To complete the circuit you either have these paired (doubling the ampacity of the system if your wiring through the car is suitable) and the turn back jumper on the rear of the last car just like "real" HEP...

OR you can have a separate low voltage connector and jumpers for the sole purpose of the safety circuit return. Anything reliable could work. Audio connectors, 12V DC cigarette lighter plugs & sockets etc. If your cars are set up with PA systems you could use some sort of multi-pin connector for that and dedicate one pin for this purpose. Naturally the power source would need to be set up so power is shut off if the circuit is not complete. This may be overkill but would add a great deal of safety.

Steve