semi truck trailer break away connection

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jonesjax

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Does anyone know if the NEC applies to semi truck trailers. I have a large company that wants me to install a 120v receptacle inside of the trailers so they can plug in the battery charger for the electric pallett machines. They want a break away cord or whatever just in case the drivers forget to unplug them before they leave. The drawing shows a recessed cord connector attached to the outside of the trailer under the rail of course. That will attach to the 120v outlet to be installed flush on the inside. Said it is so they can load the product close and seal the trailers so they will be ready to go in the a.m. The only comment I had to them was of concern of the battery fumes in a sealed compartment.

Any ideas on the break away cord. They plan on using heavy duty extension cords to plug the trailers into the existing outlet by each loading ramps.
 
IMO a straight blade male inlet on the rear of the trailer would do it.

(A Straight blade version of this)

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If you want to get fancy and have money to spend they make a breakaway plug and outlet that is used for emergency vehicles like rescues and fire engines.

Don R knows who makes them.
 
jonesjax said:
Any ideas on the break away cord. They plan on using heavy duty extension cords to plug the trailers into the existing outlet by each loading ramps.
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The challenge for breakaway cords is preventing stress on the connectors and tension on conductors which could cause them to break or come loose. You might be better off making a short male cord about 1.5' long attached to the trailer. Use 3/32" steel cable 1' long solidly attached to the trailer and back of the cord cap. Make an extension cord attaching the same kind of reinforcing cable attached to the dock as close to inline with trailer plug as possible. The idea here is to have the steel cable create a straight pull on the 2 cord caps without any tension on the cords.
 
Jim W in Tampa said:
On left side of trailer near the front install a flashing red light that alerts driver that it is pluged in.Cheap and safe.
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Not bad.

If you want to get fancy, install a normally closed 120 volt air valve in the E-Brake air line that when powered vents the E-Brake line to the atmosphere.

As long as the cord is pluged in they will not be able to release the brakes.
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Not sure how the DOT would feel about this.
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They make an inlet that is essentially a NEMA 5-15, but it has a 12v solenoid plunger inside that will eject the plug cap when 12v is applied. That is, when you start the vehicle, the plug cap pops out of the inlet by mechanical means. I've seen them on fire trucks and ambulances.
 
You can use one of these.
They are connected to the ignition circuit so that when you start the vehical the cord ejects. Not sure what you would connect it to on the trailer to initiate the eject.
Don
 
iwire said:
Not bad.

If you want to get fancy, install a normally closed 120 volt air valve in the E-Brake air line that when powered vents the E-Brake line to the atmosphere.

As long as the cord is pluged in they will not be able to release the brakes.
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Not sure how the DOT would feel about this.
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If your going that far you'd have to add a relay in the starter solenoid circuit so they can't even start the truck... otherwise they'd probably drive off with the trailer brakes still locked... :D
 
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DaveTap said:
If your going that far why not a relay in the starter solenoid circuit so he can't even start the truck.
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I would except it is a trailer, no telling if it is hooked up to a truck or not.
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I think it would be better if there was a pneumatic plug ejector for a trailer box. As soon as the truck is started, the air starts to fill the lines to take the trailer brakes off. You don't necessarily have 12v going to the trailer unless the driver taps the brakes or something like that. In fact, when yard jockey's are shifting trailers around, they often just hook up the air line and don't always connect the electrical line to the brake/turn signal lights.
 
mdshunk said:
I think it would be better if there was a pneumatic plug ejector for a trailer box. As soon as the truck is started, the air starts to fill the lines to take the trailer brakes off.
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Now that, if available would be very slick.
 
You said this was a large company. Most docks that I've seen at large company's have trailer restraints mounted to the building to prevent accidents.

These restraints often get interlocked in some interesting and complicated ways. Preventing the restraint from freeing the trailer until the charger is unplugged should not be difficult. If your building has these it would be the first place I'd look to solve the problem.

If your building doesn't have them then driving off with a cord plugged in is no big deal compared to driving off with a fork truck+driver in the trailer, so they shouldn't be too worried. ;)

Guy I know was just telling me about an accident at his work where the above happend. He was yelling about how the driver messed up because he didn't bang on the side of the trailer before he pulled off. The whole time I'm thinking, that's your safety system?
 
"dock locks" don't always work. They latch into the "ICC bumper" of the trailer. If you've been behind a trailer in traffic that has had its ICC bumper bent outwards, that driver at one point pulled away from an engaged dock lock. I've seen more than one dock lock pulled completely out of the mountings. I know that dock locks are touted as being able to eliminate "early departure" accidents, but they don't always work. There is a great video of an actual early departure accident here: http://www.ritehite.com/VRS3web.html where the forklift even falls off the dock. It's under 'trailer/dock seperation' and 'early departure video'.
 
Thanks for the link. Since it's part of rite hite's sales pitch I'm going to guess a dock lock wasn't involved ;).

But seriously, they may not be a cure all but I'd rather have one then not if I'm on that lift truck. Also, every one that I've worked on has had a big, bright, traffic light that shines into the trucks mirror. Green=go, red=stop.

Even I can follow that.
 
Remember that a lot of time the trucks are idling while at the dock, or wherever else. If there's going to be an ejection button it needs to be on the brakes, not on the ignition.

(I had a boyfriend who was a 727 pilot and sometimes truck driver. I've learned more about trucks over the years than I care to admit ...)
 
Many places require the trucker to unhook from the trailer.Many of them drivers lack sleep and might easily mess up and pull away from dock before its ready.How much are they willing to spend on making this safe ?Many ways to solve this but could be costly.What is the voltage the fork lift needs to charge ?
 
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