Does anyone recognize the circuit breakers in the attached photo? I'm in need of a replacement for the 15A breaker/switch marked "Heat".

I am also looking for a higher reading ammeter than the 1000 Amp unit shown in the other picture. This is for a 50mV shunt.

Tom Mack
Cincinnati, OH
513-458-9192 cell

The circuit breakers look to be a standard design used for marine applications years back. They should be readily available but I would need to see the back of the panel to verify.

These look to ne Texas Instrument "Klixon" circuit breakers. As mentioned if you open the panel and check the body of the breaker it should have manufacturer's name and also the amp and voltage ratings on the side.

On the ammeter, just take it apart. You can usually remove the scale from the rest of the mechanism, just be careful not to bend the needle. Then have a new scale marked over the old one.

Thanks for the pointers on what circuit breaker brands to look for. The "Klixon" suggestion was very helpful. Unfortunately the locomotive is not close to me, so I only had pictures. Otherwise I would have just pulled the breaker. I was hoping to at least identify options before I went back and actually pulled the breaker so I would already have some potential suppliers in mind. The help received was just what I needed!

Tom Mack
Cincinnati, OH

First you would need to change the current sensing shunt, or install a voltage divider across the shunt.

If 50mV = FS (Full Scale) = 1000 amps then the resistance of the shunt is .05/1000 = .000005 ohms (0.05 milliohms). So you could get a shunt with an even lower resistance, an 0.025 milliohm shunt would display 2000 amps with the needle all the way to the right.

Or you could put a 1000 ohm resistor at the top of the shunt, connect it to another 1000 ohm resistor to ground and connect the meter to the junction between the resistors. That would also cause the needle to go all the way to the right when 2000 amps is flowing through the shunt.

You can use different resistor values to make "Full Scale" equal to any value above 1000.

Cheers, Kevin