Leonard and Lionelsoni [Bob Nelson] and any others. Question on wiring from electrical panels

[ChiefEagles]

I know these two know their electrical wiring and I'm sure there are others who do too. It has been a long time since I finished my course in electrical wiring at NCSU. I saw a post on another forum [I had gotten an email from this same person over a year ago] stating that to keep transformers in phase, you have to have them plugged into the same power source outlet. Why? He says that if you use different legs from your electrical panel, they will not be phased correctly. Another way of saying this. With 240 V feeding into your panel, one leg goes down one side and the other leg down the other side. Your breakers for 120 use only one side. If you use an outlet feeding from breaker on one side of the panel for one transformer and another feeding from the other side, they will not phase. [?] I thought as long as you had the transformers with the same ground side plugged to the ground [common in the panel], they would be phased.

I'm going to be feeding 240V from a 240V sub-panel into the train room to another breaker panel for trains only. Then circuits [with breakers] from it to various outlets under my benchwork. I'm sure my main transformers, TMCC equipment and DCS equipment will be feeding from the same breaker. I may have other transformers for acces. power or certain blocks at other locations. Will I have to insure they are powered by outlets from the same leg in the panel for the train room to insure they are phased? [I know that if the transformers are independent and not connected to other parts of the layout {such as commons in blocks and seperate acces.}, they do not have to be phased. I have always had a personal rule to have all transformers in phase just in case]

[Roger Bielen]

Chief - With my layout I've found that a 20A, 120V circuit has been sufficient. I normally use two 180W bricks with a TPC (my TR1), with a 135W and PM (my TR2) that I can switch either loop to if I decide to run a conventional engine. For accessories I have my old S type for variable voltage needs and a monster 12V open frame I picked up from one of the mail order electronics houses a few years back (it has more capacity than I'll ever need).

If you feel you'll need more than 20A put your engine running transformers on one circuit and accessories, with separate common, on another.

[Roger Bielen]

P.S. - Remember 20A @ 120V is approx. 2400W ( not takeing power factors, losses ect. into consideration), a heck of a lot of power.

[Anonymous]

As long as the diffent outlets are powered from the same side of the panel you should not have a problem. It is easy to check the transformers to see if they are in phase.For my train room I use 3, 20 amp circuits.

Dale Hz

[ChiefEagles]

OH Leonard and Bob, where are you hiding??????[;)]

[Roger Bielen]

Sounds like you already have your outlets wired.

[lionelsoni]

It is true that half the outlets in your house are indeed out of phase with the other half. Look at it this way: The sine-wave voltage on one hot wire of your 120/240 service undulates back and forth between about 170 volts negative to about 170 volts positive, relative to ground, 60 times a second. This gives you 120 volts RMS (root-mean-square) between that wire and ground. The other hot wire does the same thing, except that, when one hot wire is at +170 volts, the other one is at -170 volts; so the difference between them is 340 volts. Just 1/120 of a second later, the situation is reversed, with the first wire at -170 and the other at +170. So the voltage between the hot wires is twice that between either of them and ground and results in 240 volts RMS, which you use for ranges, air conditioners, water heaters, etc.

This phase reversal or 180-degree difference between the two hot wires that connect to the transformers' primary wIndings is reflected directly in the secondary windings. So it makes a difference where you plug them in.

Having the transformers in phase is necessary only if you are running trains from a block powered by one transformer into a block powered by another. As I have often preached, the accessories and switches do not care. Otherwise, it would not be possible to power anti-derailing switch machines from DC and the trains by AC, for example.

You could get the transformers' outputs into phase by wiring half the outlets backwards, with the wide blade hot and the narrow one grounded. Do not do this. There are good reasons for polarizing the plugs the way they are; and convenience in running toy trains does not figure into it.

You could get all the outlets into phase by reversing one of the phases using an isolation transformer. This would be a lot of trouble and expense.

I suggest trying to run other stuff, like room lighting, on one phase and dedicating the other phase to the trains.

[Anonymous]

My train room is the former dining room of the house. I will be using outlets on different sides of the room. The electrical panel down in the basement was labeled by a blind man, or so it seems. It is very hard to read the labels and I have no idea if all the outlets in that room come through one circuit breaker (i.e., from one side of the panel) or if it is fed by different sides of the panel. My power strips tell me that some outlets in that room are grounded and some are not, so I think the outlets probably come off different circuit breakers, and hence might come off opposite sides of the panel. I'm not worried about some outlets not being grounded since the plugs on my 180 watt power bricks for my modern ZW's are not 3 prong plugs anyway. I am worried that transformers plugged into outlets originating on different sides of the panel may not be phased correctly. Ideas? Suggestions?

Is there a way to know at the location of the electrical outlet what it's phase is compared to another outlet in that same room?

[Big_Boy_4005]

Trevor, unless the house is really old or has been remodeled a bunch of times, there is every chance that all of the outlets in any given room are on one breaker. All outlets on a single circuit are by definition in phase. Just turn off the breaker, and all the dead outlets are the same phase. Keep in mind that when using multiple old sytle transformers with nonpolarized plugs, the plugs may need to be flipped over to be the same polarity.

If you look at the breaker panel, there should be two columns of breakers. The way the panels are constructed on the inside, breakers in the same row are on the same phase. As you go down the column, alternating rows are on the different phases. This arrangement makes it possible to get 240 volts for large appliences, by having a double tall breaker which connects to both phases.

[ChiefEagles]

Thank you Bob [Lionelsoni]. You explained it very well. Now I understand. Glad to have you back from your trip. Thanks again. [that server error thing again that hits late at night, wake up Yankee server [;)]]

[daan]

QUOTE: Originally posted by TrevorsTrains

Is there a way to know at the location of the electrical outlet what it's phase is compared to another outlet in that same room?

There is a way to find out if the cirquits are in phase, you need a voltmeter to find out. Set the voltmeter to 1000 volts AC, plug one of the wires in the live leg of the outlet on one side of the room and the other in the live leg on the other side of the room. If they are in phase, it should read 0 volt. If they are not, you'll read 240 volts.
It doesn't give a problem when you power the lights from one side and the layout from the other, as long as you don't combine the wall outlets to power the trains.

[Anonymous]

Frank
Sorry, I have mostly been off the air playing , nurse, waiter and house-husband since my wife's knee surgery on 12/23 and I ain't very efficient at any of the roles! [You got a lot of good responses and folks ought to print and retain Bob's technical explanation of the built-in "phasing" as regards the power company's service].

Anyway, I agree with Bob Nelson's[and others] recommendation at the end of his post-------assign one circuit to lighting and one to the layout. A 15 amp lighting circuit and 20 amp "appliance" circuit dedicated to the layout would make sense to me.

As Roger noted the 20 amp circuit has 2400 watts gross capacity and if you count on a factor of 85%, or around 2000 watts net as a rule of thumb, it will power transformers on an enormous sized layout. [eleven 180 watt bricks, or five Z-4ks, or seven postwar ZWs, etc].

Just as a personal preference I phase all AC transformers used on a layout and then don't worry about whether "foreign" ovals, blocks or power districts might be joined or crossed in the future or whether someone is gonna "piggback" on a layout common.

Good luck Frank and get to work![:)]

[ChiefEagles]

QUOTE: Originally posted by Leonard

Frank
Just as a personal preference I phase all AC transformers used on a layout and then don't worry about whether "foreign" ovals, blocks or power districts might be joined or crossed in the future or whether someone is gonna "piggback" on a layout common.

Good luck Frank and get to work![:)]

I personally do the same. Then no problems or worries. Hope the wife gets along OK. Thanks