using postwar transformer for accessories

I would use 8 amp slow blow or 8 amp breaker assuming proper bus size. The breaker on the TW should still function to protect the transformer.

Dale H

Hi

  I also use postwar transformers for access,lights & switch power, I have over a dozen 1033's in use. I use a 10 amp in-line fuse between my transfromers and my terminal strips. I use 3 terminal strips per 1033 transformer because with the 1033 you can get a total of 3 different voltages on the output, two fixed and one variable. I then run my access,lights,etc wiring to what ever terminal strip's voltage best suits the need. You can get these in-line fuse's/fuse holder at Radio Shack or a hardware store.

Hope this helps,

Jeff

The easiest type to use is so-called automotive, in-line fuse holders, like this:

http://visforvoltage.org/files/u1786/NewFuseBox.jpg

As to the rating of the fuses, you will have to be the judge.  Fuses are rated in amps.  You need to decide how you will be wiring the accessories. I suggest that a few different wires be used for groups of accessories. the accessories will be wired in parallel.  You need to take your digital ammeter and power each typical accessory, and measure and make a note of its current draw in mA. (milli-amps)

Then you just add up the amperage for each group and put a fuse of the appropriate size (rounding up and adding a few amps) in series with each hot lead. All the return leads can be run to the home location without fuses.

hot---fuse---accessory---return

          ---accessory---

          ---accessory---

          etc

HI, Check the accessory instruction sheet and it should tell you what voltage level it needs and how many amps it will draw. If it says 3 amps then use a 4 amp fast blow fuse.

If they tell you to use 16 VAC then that is what I would apply to it, no more or no less. But for current, or amp draw you wont to be about twenty percent above the operating draw.

With todays electronics I would always use a fast blow, or trip current protection device.

For lamps you can use a regular fuse because their draw could change as they heat up but they will not fry from a current spike.

Remember the above is just a rule of thumb. Some equipment has a real high start up current draw as is the case with air conditioners, so you would wont the trip value to be twice as high as the run  current. But I doubt if you will find any accessories in the toy train world that acts like an AC unit.

Remember to always use a conductor that will match your interrupter trip value. Such as a number 14 gauge wire on a 15 amp breaker. It is OK to have a conductor that will carry more then the trip value in amps but you never wont to have one that is rated for less current then the fuse or breaker value. That is the thing that cause most  residential fires.

 A wire that can carry only eight amps like a number 18 gauge will get hot and start smoking long before a fifteen amp fuse or breaker would open.

Be safe and have fun.

Art,

Your suggestions are right on. I'm currently using three prewar Lionel Z transformers for my accessories. I too, am protecting everything with fuses. The size of each fuse depends upon the total current draw of each circuit. Each fuse assembly (screw-in) is mounted in my control panel. This way I don't have to crawl under anything to change fuses, should one blow. Each fuse is fast blow for protection. I might add this one suggestion.  Color code each circuit under your layout for ease in trouble-shooting.

one thing to keep in mind,to protect the transfomer, size the fuse to 80% of the max. output of the transformer. eg a 1033 rated at 90 watts means that at 18 volts the max. current is 5 amps, using a 10 amp  fuse won't do anything, draw anything near 5 amps and the transformers' breaker should trip. The 80% rule is to protect from early burn out caused by constant usage at or near max. rated output. Hope this helps.

regards,

Joe Geiser

Alternate to Fuses that must be replaced:

Protect Accessory circuits with 4 amp maximum.  Higher amperages will allow meltdown before tripping.

Use Polyswitches for short circuit and overload protection with auto reset. They automatically reset when fault is cleared.

Available in variable amperages and cost under 60 cents each. Buy a bunch and use the lowest value that will carry your load for maximum protection.

For instance, Put a .5 or 1 amp value in the line to an uncoupling section to prevent meltdown.

Order at http://mouser.com/catalog/catalogUSD/641/600.pdf

White arrows point to Polyswitches:

Great idea Susan, I have been dealing with Mouser for years and the next time I order something these Polyswitches will be at the top of my list.

Amazing what you learn here!!!!  I have been using a 'V' for 20 years to power lights, etc. and have NEVER THOUGHT about using fuses for protection.  I use a Z1000 for other accessories like the magnetic crane, gatehouse shed, etc.

I do use fuses for track power but never ever thought about using them for accessories too.

THANKS!

- walt

Your guy was referring to "Lock rotor amps" This is that first jolt when motors start up
It's not really a factor in our little worlds and is used mainly for larger motors like in your heat pump.
Lighting load doesn't have dual amperage ratings because it's load is instantaneous. 
Susan gave some very sound advice. never exceed the amperage rating for the  wire you have for your accessories  and fuse each operating accessory. Lighting load can be figured up by the cumulative of all your lights and fusing accordingly   .Fast blow fuses should always be used for these small electronics.

Using a axillary transformer for accessories is always a good idea.You should also gain the knowledge to  use LED's and install them in your buildings as the incandescent bulbs burn out  . LED's pull 1/10th the current of the incandescent bulbs further extending the useful life of the transformer your using now.
If used properly they last a lifetime .

David

My thoughts jdevleerjr.  Being a newbie to mrr.  I've been reading an awful lot of forums.  I've been seeing a lot of references to protecting transformers.  Since this is electricity we're dealing with.  A breaker/fuse is suppose to be employed to protect the wiring/accessory.  I don't have any accessory buildings yet, nor do I know how they are designed/wired.  But if an accessory building has 16/22 gauge wiring in it, you need to size your fuse/breaker for that as well as the wiring leading up to the building/accessory.  Otherwise the heating of the wire/accesory, will result in smoke.  And we should all know what letting the smoke out of something causes.  CB/fuse protection selection should have nothing to do with protecting the transformer in my opinion.

You always protect your transformer unless you just like buying them.
If your accessory output is 10 amps at 14 volts then you want a 10 amp fuse protecting it. I can buy a heck of alot of 10 amp fuses for whats it's gonna cost me to repair that output if I burn it up.

Operating accessories like a gantry crane or coal loader should have their own fuse but the buss wire feeding them can be larger than the wire branching off to the accessory itself(thats where the fuse should go) . With Lights it's a little different . it'd be impractical to fuse every light so we add the total on that circuit and figure wire size needed for our buss and fuse size accordingly also taking in to account the transformers rated output so we don't overload it.

Fuses are cheap blowing one will cost you 10 cents .That's a far cry from a repair bill so they are definitely worth the effort.

David

I tried some 8 amp polyswitches but did not use them because they did not react very fast when the line was shorted. The 1.35 amp ones do in passenger cars. I assume the purpose of the added fuse is to protect the wire. The transformer already has a thermal breaker and although it is slow reacting it should protect the transformer if it is operating correctly. Slo blow fuses will still protect the wiring unless branch lines are very small and can take the surge of a PW accessory.

Another thing to consider is that these PW type accessories generate voltage spikes,harmless to accessories of that era but if you also have modern accessories LED crossing flashes etc. with PC chips the problem should be dealt with with diodes or TVS devices or damage could result.

Dale H

Why add fuse protection at all to a "lights only" circuit (LED or incandescent)?  What is the downside?

Thanks

TomB

Protection is dirt cheap.

Breakers or fuses to protect transformers from overcurrent surges and Transient Voltage Supressors[TVS] to protect the load from Voltage spikes. A voltage spike is not a "short" and will not trip a breaker or blow a fuse.

All of the protection components together are inexpensive and it makes no sense to ignore the protection afforded.

EEs such as Cam, Bob Nelson and Dale Manquen have all avocated overcurrent protection via breakers/fuses and, in particular, TVS to snub voltage spikes against fragile components.  A very experienced Dale H is sending the same message in his post above.

Thanks for all the great responses.  I plan to head to the automotive store to pick up some in-line fuses for my TW.

Another quick question.  

I have a few Lionel CW-80 transformers.  If I use the TW to just power things with lights only, such as buildings and use the CW-80 to power all my accessories, do I need any other protection since it has a modern breaker inside?  What about using the a CW-80 for my switches?  Again will I need any other protection?

I am going to rephrase my previous question too in hope of a reply.  Why would  a circuit that is dedicated only to lights require inline fuse protection?  I "get it" that inline fuses are inexpensive and easy to install, but do they serve a purpose on a "lights only" circuit?  EE's probably fuse their Christmas tree lights but that (to me) doesn't mean that it is necessary. 

Thanks,

TomB  

All transformers that I am familiar with have internal circuit breakers to protect the transformer.  I have installed over 30 older transformers to light, accessory and signal circuits without any other protection.  I, too, do not understand why extra protection is required.

I do understand the need for extra protection when running trains with modern electronics and using older transformers.

Seems like an overkill to me.

Happy railroading,

Don

Boxcar.  In response to your question.  Yes your assuming right there's very little draw of current if your talking leds, incadescents can add up though.  The reason you have fuses is to protect the circuit.  The circuit is the wiring.  If those leds or incandescents create a short as a result of burning out or failing, and no fuse is in line, then the wiring is going to overheat until the insulation catches fire.  What's the wiring in contact with where it melts and gets really hot?  Most likely flamable material. Now whats the probablility of that happening?  I don't want my house burning down because I didn't want to spend a few cents for some circuit protection.  It's really no different than the circuit breaker panel in your house. IMO. Dave.

PS.  My statement needs to be clarified.  The type of tranformer does have a bearing on this topic.  My CW80 does have short circuit protetion built in.  But I'm not faamiliar yet with its circuitry.  My ZW I just acquired is where the real problems come in.  I don't like it's design and concur with others on the need to modify it.  In fact I just ordered $50 dollars worth of parts to modify i and protect the output side as well as the input side.  Has anyone recorded the tempreature of the PWZW after operating for a coiuple of hours or so.  I just ordered a thermal switch and took a guess at 50 degrees centigrade.

Well LOL Most EE's or me for that matter don't fuse their Christmas lights because if you know anything about electricity you know that for the last 20 years UL rated Christmas lights have fuses built into the plug.
Now to answer your other question you fuse lighting circuits because even though it probably won't damage the other lights during a short this stuff can still cause a fire not to mention the aggravation of replacing the melted wires and if the short occurs in the buss wires you could damage your transformer.

David

Sorry jdevleerjr, I didn't mean to step on your post.  I didn't mean to change the topic.  If anyone was geting ready to respond to my thermal question please don't do it hear.  I'm going to start a new topic.

Dave

Christmas tree lights are sometimes fused because the wire used is thin, #22 sometimes and  is too light to carry a lot of amperage. In the case the user pugs in too many strings end to end the fuse will blow protecting the wire keeping it from overheating. Obviously they also blow in case of a dead short.

Dale H

I'll ignore your first comment because you obviously didn't understand my point about the Christmas tree lights example...

 Now, about your warning of a the possibility of a short, melted wires, transformer damage, etc...assuming that the lights are wired in parallel (we are talking low draw incandescents or LEDs here only), and that the circuit is initially wired "correctly", and that the power draw does not overload the transformer, how likely is it that a short suddenly develops within that circuit? Discounting longterm aging of the wire insulation, how might that event happen?  Assuming that a preventive measure is desired(?), how does one size the fuse - current draw, wire ga., other?

Thanks

TomB 

Don, "I do understand the need for extra protection when running trains with modern electronics and using older transformers." or on a first date with someone you don't know very well. 

Don