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Lighting Problem

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  • Member since
    September 2006
  • 146 posts
Posted by Boise Nampa & Owyhee on Monday, April 9, 2012 2:37 AM

Gents......


I'm an advocate for turning off everything when not in use....... Just ask my kids  ! ! ! !

After that......... If your lights are working correctly, as in no shorts, you could run them off of a car battery that can throw four of five hundred amps. Many pre-war modelers ran on car batteries.  Things got a little exciting when they had a derailment but that is another story. 

Current flow is not established by the current source but the consumers in the circuit.  As you add consumers (light bulbs) your current flow will go up. But a normally operating will never move all of the amp capability of the battery due to the internal resistance in the bulbs. If the current source established current flow, and you have a two hundred amp service to your house, you could argue that there was 200 amps in each circuit in your house. That is not the case.


This is an over simplification as I'm trying to stay away from some sometimes complicated math... but it is enough to get you through this.

see ya

Bob

  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Sunday, April 8, 2012 9:33 AM

peahrens

can the powerpack put out enough power to create a fire hazard if a bulb assembly or lamppost has a short / defect? 

It certainly can.  A power pack with higher output Amperage can cause wiring to overheat from a short circuit and start a fire before the power pack's internal circuit breaker shuts it off; especially if your wiring is close to anything flammable.

 

  • Member since
    January 2010
  • 2,616 posts
Posted by peahrens on Saturday, April 7, 2012 9:41 PM

The Bachmann and its power supply are in the trash and they certainly were malfunctioning (maybe because we overloaded them).  A Railpower 1370 (18 volt-amp) has replaced it and things overall work fine.  Except one lamppost acted up initially...smoked a bit and then flickered off a couple of times, at 75% on the rheostat. 

Replacing it fixed that, but I'm still concerned that a 12(?) volt item can smoke (a bit).  I am worried about my grandson monitoring this stuff...should a fuse be added, etc? Of course I've advised never leaving the room with the lighting components on, but still concerned.  E.g., can the powerpack put out enough power to create a fire hazard if a bulb assembly or lamppost has a short / defect? 

Paul

Modeling HO with a transition era UP bent

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,483 posts
Posted by MisterBeasley on Saturday, April 7, 2012 3:51 PM

I think you overloaded the Bachmann supply, but it probably has an internal circuit breaker that would have protected it from damage.  The gradual deterioration of the brightness of the bulbs tells me the supply was overheating without tripping its circuit breaker.  If this is the case, you are better off without this thing anyway.  The breaker should have tripped first.

It takes an iron man to play with a toy iron horse. 

  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Saturday, April 7, 2012 9:02 AM

You have overloaded the Bachmann power pack.  It has an output of only 1 Amp or less, and that many lights, particularly if they are incandescent bulbs, need much more than 1 Amp of power.

Ohms law for DC Power is P=EI, or Power (in Watts) is equal to Voltage (E) multiplied by Current (I), or in this case, 12 Volts x 1 Amp = 12 Watts.  It doesn't take many incandescent bulbs to equal 12 Watts of current draw from the Bachmann power pack and cause it to overload and burn out.

The Bachmann pack is so inexpensive it may not even have an internal fuse or circuit breaker.  Whether you would be able to open up the Bachmann power pack and replace the fuse, if it has one, is probably not worth the time and effort, because it would just blow again.

As near as I recall, the National Electrical Code and Underwriter's Laboratories don't mandate a fuse or circuit breaker on the output of low voltage devices, since the transformer's secondary winding wire itself would tend to melt down from an overload and simply stop working before a fire could result.

  • Member since
    January 2010
  • 2,616 posts
Lighting Problem
Posted by peahrens on Saturday, April 7, 2012 8:54 AM

Hi, I've been adding lighting to my grandson's 4x6 HO layout.  I used the Bachmann powerpack that came with his set, hooking to the DC side to be able to dim the lights.  Bought a Railpower for the trains so the Bachmann is dedicated to the lights (and 3 AC switches).  Yesterday, I added 2 more building lights (the Busch threaded bulb in a yellow stand type) and 3 Walthers streetlamps, giving a total of 12 building lights and 6 streetlamps.  All worked fine before the latest additions, but soon after the streetlamps started operating dim, then all the lamps, then hardly at all.  After waiting, the building lamps seemed ok (maybe not full brightness) but the streetlamps very dim (I have each type on an Atlas connector switch).  Definitely something wrong.

I jumpered power from the Railpower to the lamp connections and they worked fine.  I'm working on the assumption that I overloaded and probably damaged the Bachmann, so I plan to try to find a Railpower for the lights before we again leave town?  Any insight on this? 

Paul

Modeling HO with a transition era UP bent

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