Fuse panel Vs. Direct Wire

[britlynz]

" So a high resistance short at say 15 amps may not trip the 15 amp breaker, and a 20 amp short on the 20 amp breaker may not trip the 20 amp breaker."

Conversely, you could conceivably get a trip on a breaker when the current draw is below 110V/20A. They're thermal devices. That's why the summer time & hot electrical compartments can be a contributors to popping breakers in RVs.

Fuses can have similar issues.

As you adequately point out, there is nothing that is 100%. Like I said before, I tend to stay conservative and lean on the symposiums of guys with pointy heads that dream this stuff up.

Ultimately, I think the the meat of protection comes down to having adequate ampacity coupled with good workmanship skills.

[Chuck Craven]

Britlynz
Yes I can see where a power panel in an RV may heat up from the sun beating on the side. Also can see it happing because the breaker panel is to small in size for the current drown through it. After all most RV’s are small houses on wheels. Some have more amenities than most houses have. I have never camped in a wheeled house. So I don’t know what problems they have. My camping has been ether tent or self made custom van. Shore power is an extension cord to a light bulb. I have been called primitive. I once went camping and woke up in the morning with an alligator yawning about 5 feet from me. That is the last time I camped under the stars. I really think the gator was eying me up for breakfast. It is really common since when doing the wiring on one of these. If you are going to the max power hungry appliances than a breaker panel and 220 split phase is the only way to go. For a battery charger, toaster, and a light bulb leaving out the breaker probably will not get one in trouble. It still takes common sense and good workmanship, if it’s chassis, body, or electricity.

Chuck

[Dale M.]

............ So a high resistance short at say 15 amps may not trip the 15 amp breaker, and a 20 amp short on the 20 amp breaker may not trip the 20 amp breaker. The current has to exceed the trip amp’s before the breaker will trip...........

Chuck

Consider this, any device plugged into a receptacle is essentially some sort of resistance short.... The more devices plugged into circuit the lower the resistance.....

If the short is high resistance and does not trip breaker it is not substantial enough to be a problem..... It just uses electricity with nothing productive being accomplished.

The math dictates if you had a 14 gauge wire (2.54 ohms per 1,000 ft.) it would have to be over 3,000 feet long (loop) to create the 7.84 ohms at 120volts to create a 15 amp draw...

The over current aspect and time line for breakers, is to keep breaker from tripping every time you have start up surge (that only lasts a few mili seconds) every time you start you blender or refrigerator or electric fry pan or microwave.......

Think you are possibly going over the edge on this issue......

Dale

[bdosborn]

Chuck,

You've brought up valid points. There are a number of situations where a circuit breaker may not protect you from electrical hazard. You're also right that a circuit breaker isn't a substitute for good workmanship and common sense. However, it certainly doesn't hurt to have a circuit breaker and there are a lot situations where a circuit breaker provides both fire and personnel protection.
Bruce

[Chuck Craven]

Dale
Yes we are probably are.
Remember a firing pan has a thermostat that controls the heat generated. Most frying pans take 1000 watts of power, that is a little less than 9 amp’s. If one would drive a screw in to the wiring inside a wall made of wood you can see it does not have a thermostat to keep the heat below the combustion temperature. If one is careful and does not drive a screw into the wiring. I don’t think it maters if it has a breaker in the trailer or not. As long as the campgrounds power pole has a breaker. The breaker is really there if your cord from your frying pan shorts out hard and sparks to protect the wiring from being damaged. You may get a black outlet or even damage an outlet but that is easer to replace than the camper. It is really up to the builder as to what they are comfortable with doing and if you are doing basic power or going over the top.

Chuck

[Chuck Craven]

Chuck,

You've brought up valid points. There are a number of situations where a circuit breaker may not protect you from electrical hazard. You're also right that a circuit breaker isn't a substitute for good workmanship and common sense. However, it certainly doesn't hurt to have a circuit breaker and there are a lot situations where a circuit breaker provides both fire and personnel protection.
Bruce

Dogs and cats have burnt down houses because they chewed on lamp cords!
They got zapped and ran a way but the cord was a high resistance short that did the damage. Still a $5 smoke detector with a fresh battery in it is a better protector than a circuit breaker from an electrical fire.

Chuck

[bdosborn]

So why not have both?
Bruce

[Chuck Craven]

So why not have both?
Bruce

As long as you are comfortable doing the extra wiring I don’t see any problem other than the maintenance. Just remember to cycle your trailers breakers (turn off and on several times) before using it and use a test plug at the power pole and inside the camper. That test plug will give you the piece of mind that all’s right.

Chuck