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  • How safe is a loco cab during a lightning storm?

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General discussion about railroad operations, related facilities, maps, and other resources.

Moderator: Robert Paniagua

 #689012  by CPSK
 
Hi;
I was curious with summer and all of the storms whether the cab of a locomotive is a safe place to be during a lightning storm.
I would think it would be, since the train is essentially at ground potential, and the cab of the locomotive provides what would essentially be a Faraday cage.
I have never once heard of a problem caused by lightning striking a locomotive.

I was riding on an Amtrak train between Port Kent and NYC and ran into a heavy lightning and rainstorm north of Albany. No problems, and it was really a good feeling to be in a train and not in my car.

FW
 #689045  by Ken W2KB
 
CPSK wrote:Hi;
I was curious with summer and all of the storms whether the cab of a locomotive is a safe place to be during a lightning storm.
I would think it would be, since the train is essentially at ground potential, and the cab of the locomotive provides what would essentially be a Faraday cage.
I have never once heard of a problem caused by lightning striking a locomotive.

I was riding on an Amtrak train between Port Kent and NYC and ran into a heavy lightning and rainstorm north of Albany. No problems, and it was really a good feeling to be in a train and not in my car.

FW
Train is better, but even a car is quite safe in an electrical storm, unless the car has a fiberglass roof or is a ragtop. I was on a NJ Transit diesel powered train coming home from work a few years ago, and one of the coaches took a lightning hit. The train continued on its way with no injuries other than perhaps afterimages in eyes and the loud bang. Don't know if that car's PA was damaged, though.
 #689210  by sd80mac
 
Ken W2KB wrote:but even a car is quite safe in an electrical storm,
Not always. Few years ago, a mother and daughter were in a car on thruway near Rochester. While car was moving, the lighting hit that car. One of two were sent to hospital ( I cant recall which one but I think it was daughter).

So sitting in vehicle wont be 100% guarantee safe during lighting..
 #689215  by CPSK
 
Don't know if that car's PA was damaged, though.
I don't think that most of the PA work anyway :-D

FW.

PS. Your call is almost same as mine:
KE2KB. Still planning on the extra!
 #689445  by Ken W2KB
 
CPSK wrote:
Don't know if that car's PA was damaged, though.
I don't think that most of the PA work anyway :-D

FW.

PS. Your call is almost same as mine:
KE2KB. Still planning on the extra!
That's why I didn't know if the PA was damaged. :wink:
 #689458  by RedLantern
 
The locomotive cab (and metal coaches) should provide an excellent Faraday cage, but having your elbow out the window (or your head) could get you in the path of the electricity.

What I've often wondered is if the ties provide much insulation from the rails in that, if a train was struck, how far away would something in contact with the rails have to be to be in the clear? I'm sure lightning can wreak all kinds of havoc for signal maintainers.
 #689520  by BR&P
 
On one line I'm involved with, it's about a 95% chance that if there is a thunderstorm, either or both of two particular road crossings will get blasted, generating a call-out to shut them off. There is a large high-tension transmission line adjacent to and parallel to the tracks. While the utility has supposedly checked everything out and claims it's OK, it seems pretty obvious it's only the crossings near that line that get the problem. It hits the track, and the diode on the far end of the approach circuit gets cooked, and it seems to back-feed into the cabinet. The lightning arrestors and fuses usually do their job OK, but they get fried to a crisp each time. It is on a short line, and back when I was doing signals there on a couple occasions I came out the next day and spent considerable time and parts getting everything up and functioning again. Darned if we didn't get another storm the next night with the same results, before even one train had gone across since the last time!
 #689549  by RedLantern
 
roadster wrote:In a thunderstorm I refrain from touching anything metal inside the cab.
Touch all you want, lightning follows along the outside of the metal housing, you can touch the metal on the inside in the same place as the lightning hits and you won't get shocked (but if your hand is close enough to the strike point, you might get burned from the heat). In a locomotive cab, you're actually more likely to get shocked by touching the talk button on your radio than you are from the actual cab steel.
 #690069  by NV290
 
RedLantern wrote:
roadster wrote:In a thunderstorm I refrain from touching anything metal inside the cab.
Touch all you want, lightning follows along the outside of the metal housing, you can touch the metal on the inside in the same place as the lightning hits and you won't get shocked (but if your hand is close enough to the strike point, you might get burned from the heat). In a locomotive cab, you're actually more likely to get shocked by touching the talk button on your radio than you are from the actual cab steel.

Correct. Just like being on airplane. Your safe from electrocution. It's the same idea of how a power company worker can touch a 50,000 volt power line and not feel a thing. So long as you are not the path to ground, you will not get a shock. Even notice birds sitting on the catenary of electric railroads? Same idea. Utility workers stay safe because when they work on power lines using the common "bucket trucks", they are not providing a path to ground. The boom of those bucket trucks is fiberglass.The truck is sitting on rubber tires and the outriggers have rubber pads. So long as the truck does not provide a path to ground, a utility worker will be safe. It's also why workers on the ground are not allowed to touch the trucks when the bucket is raised.

In a locomotive, if it's struck by lightning, the steel body will ground to the trucks, which will ground to the wheels which will ground to the rails. There is really no way for you to be a better ground then that. Bottom line, your safe. Just close the windows. The locomotives body will protect you.

Try not to forget that your sitting on for all intensive purposes, a power plant. A diesel Locomotive produces enough power to easily power dozens of homes and easily KILL YOU. But you are safe because a locomotive rides on steel wheels on steel rails. If a power cable on the loco were to become damaged and contact the locomotives frame, you would not get a shock because the cable would ground to the rails. That is why manufacturers have no problem putting so much metal in a locomotive cab. There is no real danger. Going in a high voltage cabinet couldget you killed because you may become the path to ground for the high voltage to the locomotives frame. So you should still heed the warning to stay out of those cabinets. But as for lightning, relax.

As far as locomotives and being electrocuted, there is really only one major danger. And that is for those people working around electric trains. Electric locomotives draw power from the Catenary system and the powers return is through the wheels to the rails. If a locomotive were to derail in such a way that all the wheels were off the rails and the pantograph were still contacting the wire, anyone who touches the locomotive and the ground would be killed. And getting off the loco would do the same. Your only option would be to drop the pantograph if possible or to jump clear. Otherwise, sit tight untill
someone can confirm the power is off.
 #690511  by sd80mac
 
NV290 wrote:The truck is sitting on rubber tires and the outriggers have rubber pads. So long as the truck does not provide a path to ground, a utility worker will be safe. It's also why workers on the ground are not allowed to touch the trucks when the bucket is raised.

As far as locomotives and being electrocuted, there is really only one major danger. And that is for those people working around electric trains. Electric locomotives draw power from the Catenary system and the powers return is through the wheels to the rails. If a locomotive were to derail in such a way that all the wheels were off the rails and the pantograph were still contacting the wire, anyone who touches the locomotive and the ground would be killed. And getting off the loco would do the same. Your only option would be to drop the pantograph if possible or to jump clear. Otherwise, sit tight untill someone can confirm the power is off.

1. NOT CORRECT! electric CAN jump at least 10 feet.

I was on project on I-490 in Chili. We were doing concrete pouring on bridge deck over Westshore. The concrete boom was about 10-15 ft away from high tension wire. The truck had 3 axiles and... you know how big these rubber tires.. 1 1/2 - 2 feet between ground and rim?? there were burn spot on the ground next to all tires. And the BONUS part is that concrete mix truck was next to the boom truck and is not physically contact to the boom truck. Probably a foot apart. the mixer driver and a construction worker were leaning on the mixer truck. The electric jumped to the mixer and knocked these 2 people down. I was the closest guy to these truck since I was the construction inspector at that time. I saw the flash between the boom truck and concrete mix truck.



2. even through locomotive is off the ground and wheel aren't on the ground, the locomotive is STILL GROUNDED because it's sitting on the ground. I dont believe there is any conduction parts between locomotive and truck. I dont think u are going to get electrouded from touching locomtive...
 #690730  by NV290
 
sd80mac wrote: 1. NOT CORRECT! electric CAN jump at least 10 feet.

I was on project on I-490 in Chili. We were doing concrete pouring on bridge deck over Westshore. The concrete boom was about 10-15 ft away from high tension wire. The truck had 3 axiles and... you know how big these rubber tires.. 1 1/2 - 2 feet between ground and rim?? there were burn spot on the ground next to all tires. And the BONUS part is that concrete mix truck was next to the boom truck and is not physically contact to the boom truck. Probably a foot apart. the mixer driver and a construction worker were leaning on the mixer truck. The electric jumped to the mixer and knocked these 2 people down. I was the closest guy to these truck since I was the construction inspector at that time. I saw the flash between the boom truck and concrete mix truck.
I never said electricty cannot arc, but Your talking about two different situations. First off, how far an arc will go depends on voltage, weather, etc. There is no set standard for arcing.

As for the situation you are talking about, a Concrete pump boom is not insulated. And high volatge tranmission lines are usually in the range of 100 KV plus. The situation you are describing is nothing like being on a locomotive. In your situation, you had a metallic boom, not insulated come within arc distance of of LIVE tranmission lines. A concrete pump is not the same as a utility bucket truck purpose built to work around high voltage. The boom becoming an instant path to ground and wet concrete only added to the issue. The scenario you encountered is typical of accidental contact with tranmission lines. It happens on cranes alot as well. Those voltages are so high that rubber tires will not help you.

Again, in the situation we are discussing in this thread, it's a totally different situation since there is constant grounding. Your encounter with power lines is only relevant in this discussion in that it's about electricity, but it does not apply to train crews.
sd80mac wrote: 2. even through locomotive is off the ground and wheel aren't on the ground, the locomotive is STILL GROUNDED because it's sitting on the ground. I dont believe there is any conduction parts between locomotive and truck. I dont think u are going to get electrouded from touching locomtive...
Don't quite undertand what you are saying here, did you mean "even though the locomotive is on the ground"? in the case of a derailment? If that is what you are saying, there is most certainly conduction between a locomotive and it's trucks. The locomotive frame is resting on the truck bolster with direct metal to metal contact. And you even have grounding wires from each traction motor going to the locomotive itself to make sure the trucks, traction motors and locomotive itself are all tied together to prevent anybody from being electrocuted. The instance i was talking about with being electrocuted by touching a derailed locomotive applies to ELECTRIC LOCOMOTIVES drawing power from a Catanary system. Not a diesel locomotive. In the situation with derailed electric loco's, the danger is very real. Just because a locomtive (or any power cable) is touching the ground does not imply it is grounded. Why do you think grounding rods on electric panels are in many cases 6 feet long? That is to make sure it is a good earth ground. Mereley toching the surface of the ground is by no means assurance that you are safe. And rubber soled boots are no assurance either. Hundreds of people die from electrocution right through there boots to ground. Certain types of materials and soils are simply not great conductors. You derail (for example) an AEM-7 and put all 8 wheels on the ground but the pantograph is stuck in the catenary. You now have 25k looking for a passage to ground. You step off and happen to step on a tie plate on the rail. Your hand on the grab iron, your foot on the return, BOOM.

Aside from taking the AMT-2 Electric Safety program (required for anybody operating under the catenary on Amtrak) i also took an electric hazard class for fire/rescue operations and they explain this situation in detail with graphic demos. Think of a typical Electric locomotive, derailed, you have the very edge of 8 flanges being your only hopeful source of ground. Those surfaces may all be on dry wood ties or ballast. Neither is a great conductor. I would not want to bet my life that it was a reliable ground. As emergency responders, we are not to touch any electric train that is derailed untill power is shutoff.You are nuts to assume that something is safely grounded simply because it's on the ground.

Diesel Locomotives are different in that when you go to idle, in most cases your taking that lethal voltage away. When you derail, your going to idle. The voltages present at idle are not normally anything to worry about with arcing and a diesel locomotives power is self contained, it does not have to have a return path for the voltage.
 #690782  by sd80mac
 
NV290 wrote:As for the situation you are talking about, a Concrete pump boom is not insulated.
I was responsing to your line - "The truck is sitting on rubber tires and the outriggers have rubber pads. So long as the truck does not provide a path to ground," That's where I get puzzled. That's a bit misleading without any further explaination. Thanks for clarify.

I was watching tv programs and attended to live demo show. They indicate that they had the power line turned off before workers could work on the line. But they still hook up a grounded wire to the line they are going to work on. Although I admit that I dont know where the other end of wire goes... hooked up to truck or simply sitting on the ground.

NV290 wrote: Those surfaces may all be on dry wood ties or ballast. Neither is a great conductor.
I'm kinda of surprise to learn that. I always told that electric always look for a least resistance way to go into ground no matter what kind of ground it is. And yes, i'm speaking of electric locomotive. So if the downed wire is still alive and is on the asphalt pavement, electric still always goes through to the ground, even asphalt. so derailed locomotives with wheels on the ballast with pantograph still in contact with the wire, I figure it's still running the electric through locomotive and it's wheels into the ground.

But thanks for pointing out and clarify. Appericated it.

Although I never intend to walk across the rail with 3rd rail nor get close to live electric locomotives. I cant trust electricity!! It could act up on it's own.. just like these 2 or 3 gofl fans got struck by lighting out of blue sky at one of golf event few years ago... not even storm is nearby..
 #690797  by NV290
 
sd80mac wrote:I was watching tv programs and attended to live demo show. They indicate that they had the power line turned off before workers could work on the line. But they still hook up a grounded wire to the line they are going to work on. Although I admit that I dont know where the other end of wire goes... hooked up to truck or simply sitting on the ground.
The grounding wire you see connected when people are working on high voltage lines is connected to a reliable ground. The reason being if the power were inadvertantly turned on, it would instantly go through the ground wire as the path of least resistance (instead of anybody touching the wire) and then trip the circuit breaker again. If you have ever watched Amtrak or Metro North catenary workers, you will see then use grounding cable or poles that they attach right to the catenary and then the other end to the running rail.
NV290 wrote: Those surfaces may all be on dry wood ties or ballast. Neither is a great conductor.
sd80mac wrote:I'm kinda of surprise to learn that. I always told that electric always look for a least resistance way to go into ground no matter what kind of ground it is. And yes, i'm speaking of electric locomotive. So if the downed wire is still alive and is on the asphalt pavement, electric still always goes through to the ground, even asphalt. so derailed locomotives with wheels on the ballast with pantograph still in contact with the wire, I figure it's still running the electric through locomotive and it's wheels into the ground.

Electrcity does look for the past of least resistance. But dry rock, concrete, etc is not low resistance. It's quite high. So that voltage may not have a return. The point is, ballast and ties are not a reliable ground in all weather. And with the volatges in question, it's not a chance to take.

sd80mac wrote:Although I never intend to walk across the rail with 3rd rail nor get close to live electric locomotives. I cant trust electricity!! It could act up on it's own.
That is a safe way to think. Unless you fully undertand it and any specifics related to the voltages and equipment you encounter, it's a good way to think.
 #690832  by Ken W2KB
 
sd80mac wrote:I'm kinda of surprise to learn that. I always told that electric always look for a least resistance way to go into ground no matter what kind of ground it is. And yes, i'm speaking of electric locomotive. So if the downed wire is still alive and is on the asphalt pavement, electric still always goes through to the ground, even asphalt. so derailed locomotives with wheels on the ballast with pantograph still in contact with the wire, I figure it's still running the electric through locomotive and it's wheels into the ground.
Your understanding is generally correct but needs a bit more clarification as follows. When the loco is on the ground there is a single path to ground and all current will flow that way. The instant a person standing on the ground touches the locomotive there are now two parallel paths to ground from the point the person touches the locomotive. The current now will split between the two grounds, in reverse proportion to the resistance of each path. (The lower resistance path gets more flow) So say the locomotive to ground path is 30 ohms (the term used to state resistance) and the person is 70 ohms. And that 100 amps are flowing. 70 amps will flow through the locomotive to ground and 30 amps through the person. Zap!