120 volt 15 amp outlet (80%) 1440 watts.   You might want to dedicate this circuit to the train room. 

ZW    150 (250)  watts.   (5) Correction

KW    190 watts.  (7)

ZW-L 620 watts.  (2)

Could be wrong, and often, Mike CT. 

wow 8! ZW's  thanks for the info (I'm not planning on 8  (lol) least not yet...

I have a dedicated 12-2  20 amp service with a 4 outlet plug just for running the trains in the train room, all of the other consumables are on their own circuit......I run 2 Z4000’s and the legacy base on that circuit alone....with plenty to spare........Pat

@Mike CT and @DanssuperO, ZW's are 250 or 275 watts, not 150. Therefore, it is 5 ZW's on a single 15A circuit.

Most house circuits are 20amp , 120 volt x 20 amps =2400 watts / 80% = 1920 watts. 

However if the circuit is NOT a dedicated circuit, you have to subtract the other loads from the 1920 watts.

Be safe. 

When you blow the circuit breaker, you have too much.

I run 6 180 watt bricks on a 20 amp circuit only for my trains which does great. All the accessories are on a 15 amp circuit.

100 watts = 1 amp, rule of thumb.  Theoretically you can power 7, 275 watt ZWs on a 20 amp circuit.  

Another thing to consider, is that in most cases, the breaker that feeds the receptacle your are using to feed your transformer(s) is also feeding other receptacles and lights, upstream or downstream of the receptacle that you are using. The light in your closet is not on its own breaker. It shares a breaker with several other devices (receptacles and lights), spread throughout the house, in an effort to share the load through #12 or #14 gauge wire that is normally found in houses, feeding small appliances. These additional loads should be factored into your equation.

Most 120V home circuits are 15A and supply lighting and duplex outlets. they typically supply multiple rooms and have up to 11 lights or duplex outlets per circuit. Appliance circuits are 20A and may be dedicated to a single load. Many homes in the past were built with 100A service @240V. Most new homes have 200A service and larger homes have 400A service.

As Eddie said, we know when too much is connected to one circuit when the breaker trips. I have 2 dedicated 20A circuits to my layout so for me the calculation is easy. I suggest the following, a ZW is 270W input and it is a reactive load so we should use about a 90% power factor. The key assumption is the duty factor. If someone has 4 ZW's it is unlikely all 4 are loaded to 100% continuously. If we use a 50% duty factor that is (270W)(4)(.5)(1.1)=590W. This is about 5A. The 1.1 accounts for the power factor. A 15A circuit supplies 1800W into a pure resistive load. Most layouts will not tax a 15A circuit unless there are a lot of non layout loads on the circuit.

Edits 3/20/'19: I need to correct 2 items in paragraphs one & four below; and 3d add a paragraph following para four.  The two changes/one addition are as follows (and minor rewording elsewhere is shown by strike-through at original word and replacement in italics):

1.  Para one: "...every 12th-squared time (or 144th cycle)...".   The procedure alludes to two hands on a clock face of 12 hours; one hand for the remembered magnetization direction on turn-off, and the other the direction of the inrush remagnetizing current on turn-on.  These directions are called 'vectors.'  The clock face alludes to a radial plot of rotating vectors.  The vectors also have 'magnitude' or strength, represented by their projection on a vertical line (axis) joining 12 to 6 (o'clock).  (The clock face replaces certain Latin terms of the math.)

2.  Para four:  This paragraph is not correct when applied to the Lionel postwar ZW.  It is correct (luckily  for your writer) if applied to the Lionel 180w brick.

3.  New paragraph after para four:  The watt rating of the postwar ZW is correctly explained as not being the output rating, but the output plus the maximum in-rush magnetization current.

Original post, corrected:  Ah, transformers.  There is an arcane science.  Copper/iron ratio?  Basic.  Magnetizing current.  Inrush magnetizing current-- the iron remembers its turn-off state.  So, every --------12th-squared (or144th cycle) time it is plugged in the magnetism is maximally pointed in the wrong direction for the current it is about to receive.  Only the coil resistance opposes this current... how do you measure a resistance so small?  Ballistic galvanometer of course.  Got one?  Got room to set it up?  Where would I put the trains!

What you need is the "convenient rule of thumb."  Why is wattage marked?  For this rule of thumb:  "If a transformer is protected on the high voltage side, the breaker generally will not trip in general use if its trip point is at twice the transformer rating."  (Rule for 180w brick).

Now right here notice that this is why you are forever being told never leave a plugged-in transformer unattended.  If it overheats, your panel breaker will not react swiftly.

Para Four:  (Written incorrectly for postwar ZW, but is approximately correct for the Lionel 180w brick, where this is an output rating, and where the short circuit impedance is 10% (GRJ's figure for this)).  The analogy is to the overhead residential distribution by 25kw pole-mounted transformers, paralleled, every  few houses.  The input fuse was chosen to carry  200% of the rated output so as to not have nuisance blowing of this fuse by the magnetizing input current whenever an outage was restored.  Note that this fuse does not protect against overloading the transformer output.  As with locomotives, there was a short-time rating to take care of the evening peak, with the transformers spaced accordingly.  This mostly worked.  The 180w brick has an output limiter preventing overload.

Paragraph Four, rewrittten for 180w brick:  This situation of excessive input current at turn-on only persists for a few cycles, so it is reasonable to use the intermittent or 100% rating of the 15-amp circuit, which is 1800 watts.  So a single180w brick would be allotted twice 190w or 380w total, assuming Lionel's wish for permission to label them "190w" was an inclusion of the magnetizing current (I do not know this was it as it could be the reported 10.5 amp trip point, and lack a measurement for this as a test fixture must be built for safety here).  The early version 135w brick had 11% impedance (my measure) which suggests an allotment of 310w.  Use 380w again to allow for upgrading.  If the other loads are also continuous, then the remaining capacity would be 1420w less 380w, or 1040w.  Four additional 180w bricks @ 190w could then be added if this were done one at a time, or as 2 pair if energized sequentially.  The leftover130w could be used to light two 65w improved color sprectum double-envelope halogen bulbs with light output equal to the former 100w incandescents continuously (i.e. longer than 4 hours).  Note:  This could be implemented with 3 triple-gang wall boxes: T-rated (tungsten inrush current) switch, red (energized) pilot light--5w, duplex receptacle (switched).  Simultaneity of energization by one person can be prevented by 80" (5x16") spacing of boxes.

Added paragraphs (2):  Postwar ZW:  This transformer is widely available, in two markings: 275w and (earlier) 250w.  I believe these differences are due to more magnetizing current being required for the later, more easily repaired, coil and core portion.  There is however a major feature which could affect this difference if it is not common to both:  One or both were designed for the Mexican market (as well as S. Calif. in part) where the residential voltage was 125v.  Then, ca. 1954, that voltage in the US was raised from 115v to 120v (electronics--117v).

Currently the over- and under- voltage allowances are 5% (about 6 volts).  An increase in voltage makes the same transformer more powerful but requires more iron; ditto if a higher output voltage can be used.  Postwar engines used 14-16v at maximum, but those with the longer motor could use up to 20v (later 21v with 120v input).  Finally, a voltage change requires the same change in iron, while a frequency decrease (to 50c) (or Hz, now) requires an increase in iron, in the ratio 60/50.  In a foreign country, only the applied voltage is easily changeable.  It must be limited so that the iron does not saturate, overheating the transformer.

These transformers were designed in 1947-8, approximately.  The nominal output on A, B, C, D is 5, 2, 2, and 5 amps, or 14 amps, or approx. 80% of the 17 amp trip point of its 15 amp breaker (Amerian practice).  The useful 3d rail output is 5 amps @16v , =twice 80w, or 160w, say 150w midrange; for accessories @ 14v & lights @ 10v, another 50w; total about 200w.  On this basis, the input breaker trip point (if there were one) is about 125 to 140% of estimated output rating. However, some say the output capacity of these transformers is more like 160w only, which would increase the inrush power factors by a quarter (to 155 or 175%).  The high leakage reactance (coils wound on opposite sides of the core) contributes to reduced short circuit current, consistent with comparative lower inrush current.  In either case, it can only be that the wattages given must be the maximum inrush power, for calculating the melting load on fuses.

[I grew up in an era where plug boards for fuses were quite common.  Fuses being expensive and money scarce, I was expected to do such figuring quite closely.]  Calculating the number of postwar ZW's on a 15 amp circuit would follow the pattern above, using the higher marked wattage for the first ZW, and successive ones the estimated steady-state load, the larger estimate of 200w being what I would use, if one-at-a-time connection can be guaranteed, limited to 1440w.  If not, the higher marked rating should be used for each ZW. limited to 1800w.

Obviously, the use of power strips can have an effect, particularly the chance of multiple simultaneous disconnects, followed later by simultaneous connects, of multiple transformers.  If it can happen, it will happen, so the rule here would be to connect only 3 ZW transformers to power strips.  Note also that many power strips are made for less capacity than the wall outlet, and this may apply to their built-in on-off switches.  I have not looked to see if this is covered in any way in the NEC.

The reliable phasing of transformers needs to be preserved once established, because of possible injury resulting from exceeding the touch voltage limit (30v) when more than one transformer is in use.  I have seen that plastic marker tapes having symbols including that for phase (Greek letter phi (O cut by a slash /)) are available.

--Frank

I run six, 20 Amp supplies on a single 20 Amp dedicated circuit, but the total load on the secondary is actually quite low, since I only run a couple trains at a time.

I developed a bit of a problem with the light switch that I was using to turn everything on. The contacts were only rated for 15 Amps, and eventually wore out from arcing at every on cycle. This ultimately weakened the 20 Amp breaker at the panel. The solution was first to replace the switch with a 20 Amp rated switch, and second replace the breaker. The system can now handle the in-rush current when the switch is flipped on.

Normal people with trains should never encounter a problem like this.

Big_Boy_4005 posted:

 

Normal people with trains

What kind of unicorn is that?

father.dragon posted:

Most house circuits are 20amp , 120 volt x 20 amps =2400 watts / 80% = 1920 watts. 

However if the circuit is NOT a dedicated circuit, you have to subtract the other loads from the 1920 watts.

Be safe. 

Most house circuits in the u.s. are NOT  20 amp circuits. Usually kitchens and garages are 20 amp but the rest of the home is usually 15 amp...

What I have done was use the  one ZW  I have to operate two separate  track  lines   that's all

then I have two KW's that  I use to use for lighting  LED's mostly and some accessories and for fixed voltage for my switches 

I do not use  full power for any transformer

I am hoping that my wattage consumption is reduced that way

So what I am hoping for more transformers means less concern for my demand on the outlet I am using

rather than use one or two at maximum output

Is this a better way to go.... Daniel

eddie g posted:

When you blow the circuit breaker, you have too much.

Uses to be .  New-er homes will have Ground-fault circuit protection, sometime originating in the electrical panel, and Arc-fault circuit protection, also located in the electrical panel.  While these types of circuit protection will, also, open on overload, they are also designed for the two other electrical problems mentioned.  The world gets a bit more complicated.  We would hope,  Toy Train transformers tend to isolate track arc, spark, and ground faults, from the safer electrical world on the cord end side of this equipment.   IMO   Mike CT. 

father.dragon posted:

Most house circuits are 20amp , 120 volt x 20 amps =2400 watts / 80% = 1920 watts. 

However if the circuit is NOT a dedicated circuit, you have to subtract the other loads from the 1920 watts.

Be safe. 

Actually, most house circuits are 15A unless it's a very new house, even then I don't know that's true.  My daughter lives in a 10 year old place, all the circuits except the kitchen and laundry are 15A circuits, and it's a place built by a major builder, Toll Brothers.

Best money I ever spent was to have a dedicated 20-AMP circuit drawn into the train room.  Elliott is right as well - make sure that whatever you use to multiplex from the 20-AMP circuit is also rated at 20-AMP. I use a surge-protector-multi-outlet power strip rated at 20-AMP. I run a ZW and a Z4000 off of it. No problems. 

Aren't we missing something? Isn't the load on the secondary important to this discussion. If DANSSUPERO has a very small load on each of the secondaries, the primaries would not be heavily loaded and thus conceptually very many transformers could be connected before tripping any breakers. So I think we should be asking DANSSUPERO, "Do you know your maximum load on each transformer?  Then I think we could answer his question more directly rather than assuming the maximum draw of a transformer being used.  Just my $.02.

Jim, we're not missing anything IMO.  If you're going to plug multiple transformers into a single circuit, you should size the circuit to handle the maximum possible load.  Today's load might be half of what is put on the transformer tomorrow.

gunrunnerjohn posted:

Jim, we're not missing anything IMO.  If you're going to plug multiple transformers into a single circuit, you should size the circuit to handle the maximum possible load.  Today's load might be half of what is put on the transformer tomorrow.

I always like deferring to your opinions. However, what if DANSSUPERO has 10 transformers and would like to use them all.  If we listen to the first response to DANSSUPERO original question, he can only use 5 of his transformers and the others will sit on the shelf maybe for no good reason.  Also some responses mentioned a 15 amp circuit then the next response talks about 20 amp circuits.  I could just as easily say lets run a "30 amp circuit" to our train boards (Please. No One Do This).  Without a doubt in my mind the best answer was by a previous gentleman who probably was saying "tongue in cheek" as many as won't trip your breaker.

I think I'm getting close to maximum.

Chris S.

Jim, you won't see me recommending more potential capacity be connected to one circuit than the circuit can carry.  Note I said potential.  However, everyone is free to choose their own way, but IMO it's foolish to have a potential overload.

Say NO to this configuration!

GRJ,

I think your picture is worth a Million Amps (or Words).  I am though, concerned as to how Chris S. got a picture of the back of my board in my basement.  I am scanning for foreign Cameras connected to my Router.

LaramieJoe posted:

Best money I ever spent was to have a dedicated 20-AMP circuit drawn into the train room.  Elliott is right as well - make sure that whatever you use to multiplex from the 20-AMP circuit is also rated at 20-AMP. I use a surge-protector-multi-outlet power strip rated at 20-AMP. I run a ZW and a Z4000 off of it. No problems. 

When I replaced that light switch, it was the last weak link in the system. The outlets are rated for 20 Amps and have the horizontal socket to prove it. I bought a 20 Amp rated extension cord, and cut off pieces and put on the special plugs to match the outlets.

The train room runs on four 20 Amp circuits. 

1. Track power
2. All other layout power
3. Layout lighting
4. Convenience outlets mounted to the layout

There are also perimeter wall outlets, but they almost never get used, because they are almost buried behind empty boxes or just hard to reach. Then there's a general lighting circuit for fluorescent ceiling lights. All of this runs a 1900 square foot space.

So, in my previous post, I said I had six, 20 Amp power supplies. Each one runs a section of the layout. I have them arranged to keep the transitions between supplies to the minimum. 

In order to ballpark secondary load I use the simple formula of 1 Amp per can motor. (It may actually be closer to 3/4 Amp per motor) Most of my engines have two motors, so let's call it ten engines per supply. I don't run many passenger trains, but they will all have LED lighting, which uses so little current, I don't even count that. 

The house rule is one train per operator. Since there's no real way to have 60 operators in the room, I think I'm safe, electrically speaking.

Bottom line, everyone should make some basic electrical calculations, regardless of the size of their layout. It's really once and done, until you change the layout.

I am in a new house built 2 years ago and everything in the house is 20 amp breakers. I wired the basement with 12/2 on 20 amp breakers. I think in. PA since this state adopted a national building code less than 10 years ago I think all new residentional construction has to be 20 amp with some new kind of fast blow 20 amp breaker for the bedrooms. They are crap and blow in a drop of a hat. 

To go directly to the question that started this thread, for many years I ran two post war ZWs, a KW and a small Marx transformer on one 20 amp circuit without ever popping the breaker.

If I were to create a dedicated outlet today, I would split the duplex outlet by breaking off the little tab between the two outlets on the hot side. They are designed for this. Using 12/3 plus ground wire I would attach one hot to the top outlet and one hot to the lower outlet. The one (shared) neutral only carries the unbalanced load.  The hot leads are then connected to a two pole 20 amp breaker, making sure that the breaker is installed across two different legs in the panel (some old brands, like Federal Pacific are set up in pairs of legs). We wired kitchens like this so that a four slice toaster and a Mr. Coffee plugged into the same duplex outlet could not exceed 80% of the breaker value. Every outlet in the kitchen was the same way.  This way the upper and the lower sockets each have 20 amps available but from separate legs. Your electrician will know how to do this. 

FireOne posted:

I think I'm getting close to maximum.

Chris S.

My last Christmas tree train is on the other side of the wall.          j

Loose-Caboose posted:

GRJ,

I think your picture is worth a Million Amps (or Words).  I am though, concerned as to how Chris S. got a picture of the back of my board in my basement.  I am scanning for foreign Cameras connected to my Router.

They're virtual cameras, you just think they're there and you get a picture.

JohnActon posted:

FireOne posted:

I think I'm getting close to maximum.

Chris S.

My last Christmas tree train is on the other side of the wall.          j

John, please post a pic of your tree, this is a police pic of a grow house.                              I guess a plant might look ok with Christmas lights on it.

Chris S. 

Big_Boy_4005 posted:

I run six, 20 Amp supplies on a single 20 Amp dedicated circuit, but the total load on the secondary is actually quite low, since I only run a couple trains at a time.

I developed a bit of a problem with the light switch that I was using to turn everything on. The contacts were only rated for 15 Amps, and eventually wore out from arcing at every on cycle. This ultimately weakened the 20 Amp breaker at the panel. The solution was first to replace the switch with a 20 Amp rated switch, and second replace the breaker. The system can now handle the in-rush current when the switch is flipped on.

Normal people with trains should never encounter a problem like this.

gunrunnerjohn posted:

father.dragon posted:

Most house circuits are 20amp , 120 volt x 20 amps =2400 watts / 80% = 1920 watts. 

However if the circuit is NOT a dedicated circuit, you have to subtract the other loads from the 1920 watts.

Be safe. 

Actually, most house circuits are 15A unless it's a very new house, even then I don't know that's true.  My daughter lives in a 10 year old place, all the circuits except the kitchen and laundry are 15A circuits, and it's a place built by a major builder, Toll Brothers.

There's the problem.....LOL

20 and 15 amp circuits have been mentioned in this thread.  One thing to remember is that a 20 amp breaker should only be installed in a panel if it is powering 12 gauge wire.  Never substitute a 15 amp breaker with a 20 amp unless you are positive the wiring it is powering is 12 gauge.   

Amen, Dan. 

And in reference to another response, a lot of new homes are reverting to 14 ga. wire on the premise that today's lighting and other loads are  more "energy efficient". Let's be honest, its cheaper to use      14 ga.!  Major builders use it all the time.  But we all know that sooner or later we will push the limits by adding too many devices to the same circuit (see A Christmas Story).  It's not hard to hit 80% on a 20 amp breaker, never mind a 15 amp even in our so called "energy saving" world.   

Our favorite  hobby magazine authors usually add the caution to ask an experience electrician to perform these kind of projects. If  you aren't one, hire one.  

Earl 

Your wife's favorite curling iron, and hair dryer.   One remodel years ago,  A three bowl vanity in a beautiful large bathroom being used by three teenage girls, all at the same time, required three circuit.  Kitchen most any appliance that says instant.