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Discussion Boards => General Discussion => Topic started by: jmmrlm on April 08, 2020, 03:46:47 PM



Title: electrical
Post by: jmmrlm on April 08, 2020, 03:46:47 PM
Is there a limit to the number of street lights (rated at 12V DC) that can be run on one 22 AWG main run ?

The main power supply I am using is of the variable type with a maximum output of 17.2 V DC, 19.2 VA.

Reason I am asking is that I had 13 lights connected and one of them had its 24 AWG feeder wires burn up.

Am I doing something wrong ?

Thanks in advance for any advice.


Title: Re: electrical
Post by: rich1998 on April 08, 2020, 04:22:08 PM
Drawing too much current.

http://www.trainelectronics.com/Meter_Workshop/index.htm

I learned to use meters many years ago to prevent this. You can also.

Rich


Title: Re: electrical
Post by: Ton N on April 08, 2020, 04:40:34 PM
Most people don't know the difference between voltage and current.
For example 10000 V 0,0001A won't kill you, that's static electricity.
10000V 1A will.

Ton


Title: Re: electrical
Post by: Maletrain on April 08, 2020, 05:40:03 PM
If I read the OP's question correctly, he has multiple 12V DC lamps connected to a 22 AWG bus by individual 24 AWG feeder wires.  And, it was one of the individual 24 AWG feeder wires to one lamp that burned-up.

That sounds to me like a short circuit in the one lamp, affecting only its wires.

If the problem had been too many lamps on the 22 AWG bus, I would expect the 22 AWG wires to burn out between the power supply and the first lamp on the bus.



Title: Re: electrical
Post by: jward on April 08, 2020, 07:24:28 PM
The most pertinent question here is are those lamps wired in series (Each one connected to another lamp in a long string) or parallel (Each lamp connected to positive and negative bus lines?)

If they are wired in series, all current drawn from the power supply passes through each bulb and its leads. If wired in parallel, current divides among the various bulbs.


Title: Re: electrical
Post by: Terry Toenges on April 08, 2020, 10:42:10 PM
Way back in the 70's, when I was going to a tech school for marine services (boat mechanics), I came up with a word to help me remember some of this electrical stuff I was learning. The word is "VEPORCIA" which means Voltage - Electromotive Force  - Pressure, Ohms - ResistanceCurrent - Intensity - Amps.
A lot of the stuff I already forgot.


Title: Re: electrical
Post by: Trainman203 on April 09, 2020, 10:38:12 AM
Most people don't know the difference between voltage and current.

“Current” is what water does in a river.  “Voltage” was when you met your first girl friend. 😱😂🤪


Title: Re: electrical
Post by: jmmrlm on April 09, 2020, 11:06:52 AM
thank you all .
maletrain and rich1998- particular thanks.
jward - all connected in parallel.


Title: Re: electrical
Post by: jward on April 09, 2020, 01:03:04 PM
You shouldn't have burned up the lead to one bulb then. If anything, you'd have overloaded the buss and burned it out. Must have been a bad bulb.

I've used 22 guage wire extensively on DC layouts for track power. I've run 3 or more older locomotives in the same block and not had a problem. The circuit breaker on my pack would trip before my wiring overheated. I'd say i put up to 3 amps through those feeders for short periods of time.  I also used the same guage wire for my switch motors, which, when the controller button is depressed, sends an instantaneous jolt of well over 3 amps through the wiring. Once again, i've burned out switch motor but never the wiring.


Title: Re: electrical
Post by: jmmrlm on April 09, 2020, 01:50:42 PM
jward - the pair of 24 awg wires that go from the 22 AWG main run just to this one bulb were fused together as if the insulation had melted and there was smoke  from this one particular area. still think it would have been a bad bulb or ???
thanks for your quick response.