If a building is wired correctly should the common of your railroad be tied to Earth ground, or is this already done through the third prong of the plug ? Is there any danger in adding additional earth gorunds to a large layout ? Thanks again, Dave
The common return conductor on your layout is not a “ground” although that term is often applied. In addition it is not connected to the home system’s earth ground. The Command Base in the TMCC system is tied to earth ground via its wall wart transformer and one can connect to that ground only thru one of the pins on a Command Base’s DB-9 connector[at the serial port].
If comtemplating connecting household earth ground to a layout, be certain that the ground at the receptacle being used is continous all the way back to the Distribution panel. It is not unusual to find interrupted grounding conductors in house wiring which can be a dangerous problem if a fault arises in the circuit.
The ony time you need to be concerned about Earth Ground is if you are using TMCC. The Command Base requires earth ground to have a reference point for the RF ground plane. This ensures proper signal propogation. You may need to provide additional ground plane references when tracks pass over/under. This is easily done and is only an issue in TMCC.
I do ground my layout common, for the same reason as one would ground the body of an appliance, that is, to make the circuit breaker trip if the layout wiring ever accidentally comes in contact with the line voltage.
As for the terminology, since there doesn’t seem to be a better concise term, I have taken to rationalizing calling the layout common “ground”, whether or not it truly is, on the basis of the outside rails’ being models of the grounded rails of a prototype electric railroad.
If you need to check to see that an outlet is wired properly you can buy an electrical outlet tester at either Radio Shack, Home Depot or Lowes, they are about $5.00 to $8.00. You can test thew outlets yourself and do the repair work yourself or have a licensed electrician do it for you.
For electrical wiring in a house the positive wire usually black(can be other colors if conduit is used) is for delivering the current to the outlet or appliance, the negative (usually white wire)or common as some call is the return wire, the ground wire will usually be green or green with a yellow stripe and it is there mainly as a safety wire in case a grounded appliance shorts out its frame, the ground should trip the circuit breaker almost instantly preventing electric shock to a person.
Lee F.
If you are running TMCC, you can not do the grounding of the “common”. This will “short” the ground plane. I know. I did that and got crazy things happening with my signal. Atlas engines really went crazy. Took the ground off, engines now run great [thanks to advice from Roy M]. Did run some direct ground planes from outside ground to various spots on my layout. That really helped in low signal areas. Now this was TMCC and not regular conventional.
Bob,
Do you run TMCC or conventional? If conventional, how did you ground your layout common?
Mike
Well, it’s not TMCC. I suppose for this purpose we could call it conventional…
The common is simply connected to the equipment ground of the transformers.
The white or gray wire is called the “grounded conductor”. The green or bare wire is the “equipment grounding conductor”. Other conductors may be any other color, including gray if they are old, except that orange has a special meaning. Black is by far the most common, with red and then blue following.
None of the wires in an AC service can be said to be “positive” or “negative”.
Bob,
That works for residential mainly but wait until you get to three phase motor wiring, in three phase all hot wires are positive, use of a negative or common drops the voltage to about half of what any two hot wires would have.
If you would run an elevator on residential wiring methods and voltages(120 volts) your electric bill would be almost double for that motor. Three phase power would not do in residential because the power demand is not there to justify the need.
Lee F.
Sorry, but whether single-phase, two-phase, three-phase, or whatever, AC doesn’t have positive and negative wires.
The line-to-neutral voltage is about 58 percent of the line-to-line voltage in an AC service.