common or ground question for large layout ?

I'm NOT certain if I'm clear on your question.  The black colored output on the transformers are called: "Negative" "Common" or "Ground."  All are the same thing.

I have a very large basement layout.  I have separate transformers for: track power, turnout power and building/lighting power.

I do connect all of the grounds together for the track power transformers and also the turnout power transformer.  It works.  I have MTH Z4000s and DCS.

The reason I link the ground from the turnout power transformer to the track power transformers is so that the non-derailing function will work.

If you are asking about the red colored, "positive" "+" also called "hot" wire then each one needs to be completely separated from all others.

 thanks john, yes i believe you answered my questions  i  wasnt sure if the black was called ground and common or both and if you can hook all them up and just isolate the power or hot wire, i thought you might have to seperate both the positive and negative, 

If you use multiple transformers, in addition to keeping ALL the power (hot) separate as stated above, ALL the transformers need to be in phase in order to connect all the commons. Here is some good info on phasing from MartyE's tips page.

One also should use receptacles for AC voltage that are on the same leg of the main panel. That can also put transformers out of phase.

yes, the nomenclature of three rail takes a little to adjust to - but, it's AC and the Common, black, or U of modern transformers is the neutral. There is power on the common (outside) rails.

I prefer to call loops or areas powered with a separate transformer channel or a separate transformer as "power districts". Separations within a power district I call a "power block".

to answer your question - one only needs to isolate the common or outside rails for triggering or activating something and to create rails for "non-derailing" action on switches, as John C. already mentioned.

I have two additional comments I would like to make.   First...  On larger layouts you should label your wiring as you go.  Yes... you may know what everything does right now. But five years down the line when you're trying to troubleshoot some obscure electrical gremlin that mysteriously appears, there will be things you can't remember. ( trust me, I've been there   Secondly...  This may not be necessary if you're familiar with household wiring, But NEVER under-gauge the wiring on your layout.  It may be gross overkill, but I use 14 AWG Romex to supply my four main distribution blocks, run 18 gauge to my terminal junctions & track feeders, and use 20 gauge for my lighting & accessories.  Since I only run traditional style locomotives, I don't need Fast-Blow fuses, but I do have the whole thing wired with in-line circuit breakers. ( I made that change after the breaker on one of my ZW's failed during a session with my two nephews   So Good Luck & Enjoy the Hobby.

Forgotten Branch ,I am glad you talked about wire size, i have 10 gauge solid to supply my terminal blocks and have 12 gauge to supply track feeders, Track feeders are 16 gauge, i assumed that would be overkill but thats what i have and use alot of and have access to. Do you prefer solid or stranded ? , i mostly have solid available

Steamnut88 posted:

Forgotten Branch ,I am glad you talked about wire size, i have 10 gauge solid to supply my terminal blocks and have 12 gauge to supply track feeders, Track feeders are 16 gauge, i assumed that would be overkill but thats what i have and use alot of and have access to. Do you prefer solid or stranded ? , i mostly have solid available

Stranded wire works best for MTH DCS command control, as well as Lionel Legacy/TMCC command control.

Is there a benefit as to why stranded is better for those systems?

I use stranded for my lighting & accessories...  But solid for everything else.  As for your wire gauges...  You may be a little over-gauged for your layout's needs. But you will never exceed your wiring's capacity, and have a derailment start an electrical fire. Something I saw happen under my cousin's X-mass tree back in 69' when a derailment happened involving an unprotected pre-war transformer.  We were inspecting a spectacular pile-up behind the tree when we smelled smoke...  The wires leading to the track were glowing bright red, melted their plastic insulation, and nearly set the carpet on fire.  Fortunately, his older brother had the mind to yank the power cord out of the wall and save the day.  That transformer was replaced in less than 24 hours. But circuit breakers have been part of our layouts and under every X-mass tree ever since.    Please pass the fire extinguisher...

Steamnut88 posted:

Is there a benefit as to why stranded is better for those systems?

Yes, the MTH digital DTS signal "likes" stranded wire.

Would I be making a big mistake if I use solid wire for the main feeders ?

Steamnut88 posted:

Would I be making a big mistake if I use solid wire for the main feeders ?

In my opinion, yes. Unless you NEVER want to use command control systems.

Solid wire has no measurable effect on command systems, where does that advice come from?

gunrunnerjohn posted:

Solid wire has no measurable effect on command systems, where does that advice come from?

OK, never mind me. Wire your layout anyway you like.  By the way, gunrunnerjohn, what type/size of wire is YOUR layout wire with?

Just don't post incorrect information and I'll never mind you.

gunrunnerjohn posted:

Just don't post incorrect information and I'll never mind you.

You did NOT answer my question!

That's right, it has no bearing on the validity of your incorrect statement.  I think 40+ years of electrical engineering gives me just a bit more qualification to speak about RF signal propagation than whatever it is that you do for a living.  Of course, if you're a world renowned RF engineer, by all means speak up.   You have your opinion, I have experience and education that says you're wrong.

So is it safe to say i can use solid wire ?

That would depend on who you believe it would appear.  IMO, it's perfectly safe and will have no effect on the command signals of DCS or TMCC.  Any benefit that stranded wire brings you with the skin effect of high frequency signals is lost with ordinary wire as the strands are shorted, making it the same as solid wire.  Some will argue that the uneven surface of stranded wire gives it greater surface area and thus makes it marginally better, but I'd challenge anyone to actually demonstrate that. 

Steamnut88 posted:

So is it safe to say i can use solid wire ?

Sure, go right ahead. gunnrunnerjohn says it works just fine.

Hot Water posted:

Steamnut88 posted:

So is it safe to say i can use solid wire ?

Sure, go right ahead. gunnrunnerjohn says it works just fine.

Won't it be embarrassing when I'm proven right?  You're like a bulldog with a bone here!

Hot Water have you had a bad experience with solid wire on a layout?

Steamnut88 posted:

Hot Water have you had a bad experience with solid wire on a layout?

Nope. I followed the verbal instructions from The MTH Vice President of Research & Development, and used the twisted pair, 14 gauge wire sold be OGR some years ago. We operate DCS, Legacy and TMCC all at the same time with no issues.

Hot Water posted:

Steamnut88 posted:

So is it safe to say i can use solid wire ?

Sure, go right ahead. gunnrunnerjohn says it works just fine.

I used both stranded and solid wires for switches, signals, etc.  One lead has both ... never had a problem related to that wire.  Use stranded 14-16 for track wiring.  Next set of turnouts will use 22ga twisted pair instead of the 28ga scrap wire used on the rest of them, some 30' from the controller buttons.  They work.  What can I say ... except each layout is different.

A layout we visited last month had all power wires to his tubular Lionel track of 22ga tucked into the holder for the middle rail .. and it all ran great. 

Steamnut88:

I am no expert by far on house wiring. What little I know says that of the three wires one has hot (power), neutral (some say ground), and ground (earth ground - called so since it connects to something metal that goes down into the dirt.). The hot and neutral carry the power. The ground does nothing unless there is a short. The ground usually connects to the chassis and is there to divert current in case of a short so one does not electrocute themselves. I think I got it straight??????????

For a model train layout one deals with hot (power - red wire) and neutral (some say ground - black wire). The third wire (the large bullet prong on the plug) I think just protects the transformer (go back to above)???? Some people use the third prong (a plug with only the third prong connected) to act as 'earth ground' when dealing with TMCC / Legacy signal issues when one track crosses over another or when a train enters a tunnel that tends to block the signal. I have heard this is not a good practice though from a safety standpoint.

I think I got it all straight..................

I also as mentioned above separate 'power' by using different transformers - track power ( further divided by blocks / spurs etc, ITADS power, accessory/lights power. One could theoretically power everything from one transformer but when a short occurs where do you start looking - track, ITADS,lights?

Joe

Model Structures posted:

Some people use the third prong (a plug with only the third prong connected) to act as 'earth ground' when dealing with TMCC / Legacy signal issues when one track crosses over another or when a train enters a tunnel that tends to block the signal. I have heard this is not a good practice though from a safety standpoint.

Actually, the TMCC radiated signal is directly connected to the ground prong of the power connector.  That's the reason why you have to use the power adapter that comes with the TMCC or Legacy base, most will not have that connection.  The outside of the barrel plug for either command base will be found to be connected directly to that 3rd ground prong of the 120V plug.

The safety consideration here is bad wiring to outlets.  If you've wired the outlet wrong and the ground prong is hot, then it's a very bad idea to plug anything into that outlet!  First step is always to make sure the house wiring is properly done, then there is no safety issue using the ground prong for additional "antenna" radiators for the TMCC/Legacy 455khz signal, it's done all the time.

Yep John you are right. I have seen some youtube videos where electricians talk about houses where the wiring (neutral versus earth ground) had been improperly installed on some wall outlets.

Joe

I am not an electrical expert, nor do I play one on TV.  I am however frugal.  When I built the layout I had 14 g house wire, solid, black white and ground.  I stripped out the three wires, the ground finds it way around the layout underside so that it is easily reached should there be a need to tap into a ground source.  The other wires serve as bus wires to locations, stranded feeders were attached using wire nuts, stranded wires (16 g)  went to the track as needed.  Layout has been up 20 years with no electrical issues.  I only run either conventional or TMCC.  Both play nice with this arrangement.