Issue 255 Backshop Q: Common for Layout

I have a "layout common" for rail power, structure lighted and operating accessories. However on some items I "homerun" a wire run of both hot and common conductors, i.e; my Tortoise switch motors.

Common Ground is Common Ground. There is no need for separate commons for track and accessories.

You will receive a lot of differing opinions on this. IMHO, the size of your layout, the number of items [lites/accessories] you are connecting to the common, how many transformers you plan to connect and the AWG of the wire will play important elements in determining whether you separate your common into one or more runs around the layout.

There is another key item and that is troubleshooting when problems arise - as they will. Separate commons will help you find the issue and resolve it without too many posts suggesting you dis-attach the components to find the issue.

Ralph

I believe Al is right if operating with DCS. I no longer have it but when I did, I paired and homerunned hot and common conductor wire runs for distribution in each power district[block,loop,throttle,etc].
For just Conventional and TMCC, as mentioned above, I use a single "Layout Common" except for Tortoise motors.

I carry a power wire and a RETURN wire to every load. In the case of the layout, I have all the returns (the U terminals) connected together at the sources. Of course all the A terminals (different sources...ie track power, lighting, accessories, etc.) are separate.
BTW, your house is wired this way.
Changes are simple, voltage drops are minimal, and current measuring is easily done.

quote:

Originally posted by DPC:

Well...it's like your house, but there's no safety ground wire. That what you are rolling your eyes about?
I don't like names for electrical/electronic things unless they are descriptive of what they do. Power wire...return wire, I like that. If you connect something to ground, then say it, when and where...if something is common, then say where and how...

quote:

Originally posted by cjack:
I carry a power wire and a RETURN wire to every load. In the case of the layout, I have all the returns (the U terminals) connected together at the sources. Of course all the A terminals (different sources...ie track power, lighting, accessories, etc.) are separate.
BTW, your house is wired this way.
Changes are simple, voltage drops are minimal, and current measuring is easily done.

A transformer is a totally unreliable source for current sensing when you have a fault(Short) because of that alot of damage occurs because the user doesn't take the necessary precautions to balance the load and fuse properly thinking that it will be protected by the breaker.

If you think that your protected when tying everything together take a look at the common welder it's a transformer too with just a hot and a ground as you call it and it'll put 2 pieces of 3/16 metal plate together all day long without blowing a fuse.

David

I think the original subject has lost it's way. The article suggested a common return path around the layout to simplify wiring.
Then there were some comments about terminalogy and whether common connections were irrevelant or not.
The distintion of where to common the common (return path) wires was kind of lost. So I suggested that I like to run a return path all the way back to the transformer for every power wire...no matter if it is track, accessory, or lighting. I do that to simplify future changes, make diagnosis of problems easier, minimize voltage drops, not co-mingle current, etc. And in the case of the ZW, all the common return wires are connected together inside the transformer. No choice there, but for some things like powering up the SC-2s with a separate transformer, I connect the U terminals together because the SC-2s and their power transformer work better that way with the command control. As to fuse or breaker protection...that's a different subject I think but my wiring allows for and includes easy insertion of an individual breaker for any circuit in the individual power or return paths.

The only true ground on an o-gauge layout is the earth ground on a TMCC equipped layout[used for a "ground plane" to overcome TMCC signal problems but --NOT connected to track any where, at anytime!

The little wall wart transformer of the TMCC Command Base connects to the earth ground of the household circuitry and is offered at the #5 pin on the serial port of the COMM Base to receive a DB-9 connector and wire run to certain TMCC control modules[TPC,ASC,etc]. Under no circumstance would you connect the #5's pin or wire run of earth ground to the layout's common return or to track--never!

The use of "ground" in describing the o-gauge common return has unfortunately become "common" usage. However, they are not even double first cousins. One is a electrical return conductor and the other is a true earth ground.

quote:

Originally posted by Dewey Trogdon:
The only true ground on an o-gauge layout is the earth ground on a TMCC equipped layout[used for a "ground plane" to overcome TMCC signal problems but --NOT connected to track any where, at anytime!

The little wall wart transformer of the TMCC Command Base connects to the earth ground of the household circuitry and is offered at the #5 pin on the serial port of the COMM Base to receive a DB-9 connector and wire run to certain TMCC control modules[TPC,ASC,etc]. Under no circumstance would you connect the #5's pin or wire run of earth ground to the layout's common return or to track--never!

The use of "ground" in describing the o-gauge common return has unfortunately become "common" usage. However, they are not even double first cousins. One is a electrical return conductor and the other is a true earth ground.

Thanks Dewey,

I am slowly coming to the conclusion that I am going to have to greatly reduce my involvement in the electrical forum . It seems that there is an over abundance of shade tree mechanics that don't want to wire things correctly and safely they just want to get it done and are more than eager to impart that misgiven knowledge to those that don't know any better.

They obviously don't work in this industry and give definitions that are obviously wrong. I won't take part in a forum that continuously encourages those that think they know what they're doing but don't have a clue who have no certification other than their self attained knowledge.

And continuously give input to the unknowing that will cause problems down the road

I was a big advocate of the inception of the electrical forum. I felt it would be a great thing for me to be able to help those just getting started to save them money and disappointment when they burned something up because they had no one to tell them how.
It's not just this thread but the majority of the threads I've participated in that it's been this way.

Thanks again Dewey it's nice to read a post from someone I know ,knows what they're talking about....Later

David

quote:

It seems that there is an over abundance of shade tree mechanics that don't want to wire things correctly and safely they just want to get it done and are more than eager to impart that misgiven knowledge to those that don't know any better.

This comment applies to almost any advice given on internet chat boards and blogs. There are always well meaning people sharing misinformation that they are positive is correct. I guess it's up to each of us to sift though it all.

David, C W Burfle is right. If you think this forum is bad you should read the electrical threads on the rv forums. They are dealing with house power not toy train power and the so called advice dispensed is a lot worse than what I have read here. Keep telling people what you think is correct but keep an open mind sometimes a person with absolutely no skills in the topic has an excellent idea. I agree a "Toy Train Layout" can burn a house down but I also think that the chance is remote sometimes a person has to learn for himself.
Ron

I have learned a tremendous amount in a short time on this forum. Let's keep it civil and please, experts, don't drop out and withhold your knowledge from the rest of us.

As a certified non-expert, my logic would suggest that all transformers on a layout be phased similarly and tied together to prevent accidental mis-connections from creating problems. I am biased, because I have spent too much time tracking down problems caused by out of phase transformers.

quote:

Do you guys separate accessory and track power commons?

I do not. Small layout, conventional operation, train and accessory transformer commons tied together.

Pete

The forum is worth every byte of storage it occupies!!!!

The gentleman who started the thread asked a simple question --- one common wire going around the layout that all components attached into. The experts who know far too much to answer the simple question usually take the question further and further off track - excuse the pun.

DPC stay and continue with your advice or make only certified electricians be allowed to post replies in the Electrical Forum.

By the way, your answer was sound "train" advice IMHO, just hidden into the minutia of expertise which sometimes experts speak. You covered all that the gentleman needed to think thru to decide what he will do. After all it is his RR to deal with as he chooses. You can offer information but you cannot make him read it and you cannot be upset if he ignores it. Think about a simple post when you see bad information - no long correction -- just capital letters saying -- BAD ADVICE OR WRONG. No need for defense of your position unless asked for it.

Stay on the forum - don't go away -- we need you.

Ralph

quote:

Originally posted by OGR Webmaster:
Common Ground is Common Ground. There is no need for separate commons for track and accessories.

Rich,

I'm glad we could arrive at common ground.

Larry

I will leave the technical merits to the folks who are actually trained in electricity / electronics.
I've built a number of layouts over the years, and typically use multiple transformers, one for the trains, and one for accessories (usually a "Z"). While there may not be any reason to use seperate commons, I have always run seperate ones for each transformer. IMHO, this is a less complex setup, and is therefore less error prone.
Even today, wire just isn't that expensive.

quote:

Originally posted by Dewey Trogdon:
RailFanRon
Where did I say the Forum was bad. On my first post I answered the question with how I wire to common return.
In a later post I gave some factual information regarding "grounds".
I have not been able to relate or connect that to CW's post. What specifically are you talking about?

Dewey ,
I think he got you mixed up with me. I guess it's because we're only about an hour away from each other LOL.

David

Dewey,
Engineeringly you are correct sir.
PCRR/Dave

Dewey, Sorry I meant to say David and had a senior moment. I edited my original post.
Ron

C W I also think separate grounds are a good idea. They eliminate the adding of currents on a common ground which could possibly overload it as more things get added to it.
Ron

My layout has DCS with its own star runs and dedicated transformer, My Custom Signal system has its own home run wiring and power supply. All my Ross switches with ZStuff motors has its own home run wiring and power supply. There is no common returns between these systems. If I should ever do acessories or lighting then they will have there own home run wiring and power supply.

It works for the simpelton that I am, so I don't have to contend with "funny wiring" or things wire nutted together whose reason is now forgotten.

As an above poster said wire is cheap. The extra spent for doing it right saves agrevation later on.

quote:

As an above poster said wire is cheap. The extra spent for doing it right saves agrevation later on.

It will not hurt to have separate runs but that is not the only "right" way. As Rich said, A common return is a common return. There is no need for separate track and accessory commons unless that is your wish.

There is one small advantage to my system. There is no annoying engine light dimming or slight slow down/speed ups as accessories or lamp loads are turned on/off.

Each to his own.

(Besides I work at an electronics distributor and can get almost any type wire/gauge almost at cost, so it lets me wire things as I please. )

quote:

Originally posted by rrman:
There is one small advantage to my system. There is no annoying engine light dimming or slight slow down/speed ups as accessories or lamp loads are turned on/off.

Each to his own.

(Besides I work at an electronics distributor and can get almost any type wire/gauge almost at cost, so it lets me wire things as I please. )

As long as one is using separate power supplies, that would not be an issue with one common return.

But like you said: Each to his own.