Hello everyone!
My best friends and I are building our first railroad layout and have selected the NCE DCC for our controls. We are getting ready to start wiring and are flumoxed about what we are assuming is the ground wire of our power. It is not clear in any of the user manuals or wiring diagrams what is to be done with the green wire and where it should be attached.
Any help would be greatly appreciated!
Work Hard! Train Hard!
A number of years ago we switched from DC to DCC and went with the five amp NCE Power Pro. We do not remember any green wire. We plugged in the 120 volt power like normal to the booster. I was not there at the time so if there was a green wire someone would have connected it from the booster frame to a 120 vac three wire power outlet frame which is ground. We were in a State owned building cellar.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
If you have multiple boosters, then there should be a common wire of the same size as you track bus wires run between a case screw of each one. The manuals show which one. This is a common for the DCC power, not an earth ground. There's no reason to connect your system to earth ground - unless you are using some oddball power supply, the power supply is isolated between the high voltage and low voltage side, no need to have a ground wire for safety on the low voltage side.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
The ground wire between boosters attaches with spades under one of the screws that holds the covers on each of my Power Pro boxes. It's been so long I don't recall that it was provided with or I added it to my set-up.
Mike Lehman
Urbana, IL
Phase synchronization in a DC supply?
Synchronization of digital waveforms with a piece of wire with a couple of crimped connectors on the ends?
I'll bet a hat it's more to eliminate problems like ground loops, the same way you tie all your frame grounds in an automobile together explicitly with braid if you are wise.
It serves as a place for the current to flow when you do get an out of phase situation. Such as when crossing the gaps between sections powered by two different boosters. No matter how perfect the wiring, there's going to be a slight phase difference, because of the way boosters link together. To be perfectly in sync, you'd have to come out of the command station and split into multiple equal length wire runs to each booster, no matter how far away it was. That's not practical, and it's also not that critical at the frequency at which DCC works.
A worse case scenario is a split pickup loco crossing those gaps - old style locos that pick up with one side of the engine and the other side of the tender, or diesels with 4 wheel pickup - 2 from the front truck, 2 from the rear truck. Can't do anything about it - when it crosses the block bounday, you're getting power from the right rail of one booster, and the left rail of the other booster. You need a complete circuit. The common wire provides that. NCE is likely the same, but with Digitrax, there IS a common in the Loconet bus connecting all the boosters. But that's just thin telephone wire. Not really meant to carry high currents. The common between all boosters should be the same size wire you are using for your track bus.
Randy:
In a recent Youtube presentation of the DCC Guy it was suggested that the ground wire also be connected to the house earth ground to help suppress static electricity discharges. What is your opinion on this?
Joe
JoeinPAIn a recent Youtube presentation of the DCC Guy it was suggested that the ground wire also be connected to the house earth ground to help suppress static electricity discharges. What is your opinion on this?
The problem is that there can be other problems on house ground, including stray voltage or noise spikes from defective equipment or connection. If you wire to ground, be sure nothing from elsewhere can get back up into the tie connection...
(And yes, I'd unplug the ground connection if there is any likelihood of close lightning strikes...)
I say keep it disconnected. The power supply is isolate, so on the low voltage side, you have an isolated power source. Hooking the ground to the house ground totally defeats that.
Not a diode Overmod, a resistor. If you want to conenct to earth ground for anti static reasons, use a 1 meg resistor, like used with anti-static wrist straps and mapts. That will protect you if somethign bad happens, like you touch a hot lead and the track at the same time. A 1 meg resistor limits the current to a level that won't hurt you. This is how the anti-static mat on my electronics workbench is connected to ground, and then is also has a nice box I mounted under the front edge to plug in a wrist strap. But I would not simply run a wire from the DCC system to earth ground without the resistor.
I agree with you about the megohm resistor, but the diode is for something else: counter EMF developed in the house ground wiring between the point where the tie would connect and the actual ground rod (or 'thing the water pipe or whatever actually grounds to') -- or high EMF in the actual ground outside, e.g. from close lightning strike. This may not be enough to shock you but it could be enough to damage electronic components. A fast-acting diode blocks such things.
You should not tie the layout ground to the nearest water pipe or anything except the actual ground in the same outlet the system plugs in to - and ONLY at one point. To do otherwise invites such ground loops and begs equipment to be damaged.
For example, after verifying that the ground wire in the line cord for my good surge protector I use on my workbench was bonded to the (metal) case of the surge protector (yes, not one of those cheap plastic surge protectors - this is a good Tripp-Lite IsoBar unit with more than just surge supression in it - keeps the line noice out of my scope and better bench meter), I connected the ring terminal from the static mat unit to one of the chassis screws on the surge protector. Everything that runs through the surge protector, AND the mat, share the same ground connection. Likewise, pick one location if you are going to do this with a DCC system and conenct that ONE point to the house ground, at the same outlet the power supply plugs in to. Any additional boosters will be covered by the heavy ground wire run between all of them.
rrinker You should not tie the layout ground to the nearest water pipe or anything except the actual ground in the same outlet the system plugs in to
I have become something of a grounding fanatic, putting heavy solid-copper rods 10' into the ground with some couplant to ensure continuity and dielectric grease where the house ground is tied to them. Laugh if you must.
Ssomething I had not adequately considered: if you were to have the boosters plugged into separate AC plugs, as discussed for the supplies to the switch machine controllers in the other thread, shouldn't any grounds all go to the same point in the ground wiring, not 'severally' to the ground pins of the receptacles providing hot and neutral AC...?
Overmod Ssomething I had not adequately considered: if you were to have the boosters plugged into separate AC plugs, as discussed for the supplies to the switch machine controllers in the other thread, shouldn't any grounds all go to the same point in the ground wiring, not 'severally' to the ground pins of the receptacles providing hot and neutral AC...?
Thanks for the explanation and clarification. The inclusion of a 1 meg ohm resister wasn't mentioned in Larry Puckett's youtube presentation but it makes sense now that you have explained it.