Tripping Circuit Breaker

by Gerry (Florida)

Question: I have a 2008 Carriage 5th wheel. One of the 110 breakers trips quite often and lately a 12-volt fuse keeps blowing BUT only when the trailer is plugged into my 2007 GMC diesel. Wires, grounds etc. all appear okay. Converter is made by Iota. It has got me stumped, any help appreciated.

Answer: It is difficult to diagnose this with the limited information provided, but here are some thoughts.

Start by asking yourself the following questions:

• What is the circuit breaker controlling? For instance, microwave, TV, toaster, etc? Most circuit breakers are labeled and show what they protect.
• Why is the circuit breaker tripping? Could it be overloaded, or is it old and needs to be replaced? If it has been tripped multiple times it may have reached the end of its useful life and the only solution is to replace it with a new breaker.
  Warning! Never replace a breaker with one of higher rating, make sure it is of the same type and rating. Please see the caution below prior to the replacement of any circuit breaker.
• What has changed? Did you recently replace an old electrical component or add a new one to the circuit that keeps blowing?

 

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Caution: If you do not have a familiarity or are not comfortable working on live ac circuits go no further.

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What you need: Phillips and slotted head screw drivers, clamp-on ammeter, replacement circuit breaker.

Step 1: Kill all the power to the 5th wheel. If it is plugged into external power, turn off the breakers at the pedestal and remove the shore cord from the external receptacle. If you have a generator make sure it is not programmed to start automatically when it senses a low battery or loss of external power.

Step 2: Remove the circuit breaker cover and make sure that the wire connected to each breaker is solid and not loose. Loose or corroded connections can cause circuit breakers to malfunction.

Step 3: Set the ammeter to the appropriate amp range.

Step 4: Find the circuit breaker that is tripping and clamp the ammeter probe around the wire that comes out of the bottom of the breaker.

Step 5: Turn the external power back on as well as the circuit breaker and the electrical load on the problem circuit. It is best to have someone else do this for you so you can monitor the ammeter.

Step 6: Is the circuit breaker holding, is it getting very hot to the touch or is it tripping? If it is tripping, was the current (amps) reading higher or lower than the circuit breaker capacity?

If the reading is lower but the circuit breaker trips and is very hot then replace the circuit breaker after you have turned off all power the RV (see step 1).

If the reading is higher but the circuit breaker is warm when it tripped, it may indicate you have an overload situation.

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Your other problem with a blown fuse should not be related to the circuit breaker problem since DC and AC power is never connected together. My guess is that the truck is causing the problem through some feed back from the truck electrical system. This problem could take a long time to diagnose. My suggestion is that you seek some help from a qualified service center or technician.

Please let us know the outcome, so others can benefit from your experience. We also like to know if the suggestions offered here are of any help.