Breakaway Switch leads melted together

[SCClockDr]

Hi All



While inspecting things for an outing this weekend I found the leads for the breakaway switch melted together. (They were hitched to the trailer wiring with household wirenuts, taped up and stuffed into the loom and taped some more. The wirenuts melted also. ) I cut all this junk away and tested the switch for continuity, it read 42 K ohms. Not good!



So my question! What is the most reliable switch brand that I should look for? The failed one is Bargman and the wire gauge looks feeble to me for the 20+ amps required.



TIA



George

 

[TowPro]

Let me try my Electronic theory here. Ohms law say E=IxR where E= voltage (14v), I = current and R = resistance (switch had 42,000 ohms). take 14/42000=3. 3 amps. This means that 3. 3 amps were allowed to flow through the brake away switch to the brakes, might not be enough to lock the brakes up, but it would make that trailer feel real heavy. Not sure why 3. 3 amps melted all the wires.



I would also pull all 4 wheels and check out the brakes and both sides of the drums (brake side and magnet side). Check the shoes for cracks.

 

[BGlidewell]

Was the tether pulled out of the switch for any length of time?



Northern sells TAP by Hoppy BASs.

 

[SCClockDr]

Hi All

Let me try my Electronic theory here. Ohms law say E=IxR where E= voltage (14v), I = current and R = resistance (switch had 42,000 ohms). take 14/42000=3. 3 amps. This means that 3. 3 amps were allowed to flow through the brake away switch to the brakes, might not be enough to lock the brakes up, but it would make that trailer feel real heavy. Not sure why 3. 3 amps melted all the wires.



I would also pull all 4 wheels and check out the brakes and both sides of the drums (brake side and magnet side). Check the shoes for cracks.

TowPro - Thanks for your response.

On your point 1 - A good switch shows dead short with pin pulled. (I should have stated the 42k was with the pin pulled, Batt disconnected. Sorry for the confusion. ) The melting may have occurred with prior owner and was well covered with tape. Further investigation while installing the replacement (Tractor Supply Store) I discovered the 12VDC wire not connected in the junction box. (Popped out of the wirenut when I moved the wires to find the correct splice) There was no voltage on either wire when I tested for the supply wire.

Point 2 - Done 2 weeks ago all was well and the TV BrakeSmart stopped the wheels as expected.



BGlidewell - Thanks for your response.

Was the tether pulled out of the switch for any length of time?



Northern sells TAP by Hoppy BASs.

I suspect this did occur some time ago.

Purchased replacement from Tractor Supply Store today as I was there for another purpose.



On the install I sheathed the +12VDC lead with tubing to prevent the leads shorting to the frame or each other in the future.

 

[WestTN]

Well, I hate to point this out TowPro, but that would actually be 330 microamps. Not a heck of a lot of heat there! If you figured that one using the calculator in Windows then you missed the 'e-004' at the end.

 

[TowPro]

Well, I hate to point this out TowPro, but that would actually be 330 microamps. Not a heck of a lot of heat there! If you figured that one using the calculator in Windows then you missed the 'e-004' at the end.

No I saw it, but figured it ment the 333 kept repeating.



Anyway, Now that I hear the rest of the story, someone pulled the pin with a fresh battery (or plugged in) and everything just keep getting hotter until something opened, which must have been the switch.