Why 30amp inline fuse on legs - Montana Owners Club

Parrothead · 09-03-2009, 04:29 AM

Ours blew. We had no idea what is was so called Tech. He said he had never seen a setup like this. So please electric experts, AL or Jim or any others, explain.
Happy trails.........................

ole dude · 09-03-2009, 05:36 AM

I believe it is there to protect the electric motor that drives the legs up and down. I also believe there is no other protection for that motor. Alot of folks have installed a larger fuse or a auto reset breaker for this protection. The breaker I installed in leiu of the fuse was a 40 amp. I feel the motor is still protected and has elimenated some unplanned failure.

Parrothead · 09-03-2009, 05:39 AM

the Tech said it was connected to a circuit breaker and thought this second protection was unnecessary.

ChuckD · 09-03-2009, 05:46 AM

I purchased a 40 amp circut breaker in place of the fuse, the few bucks it cost is well worth it. and if there is a breaker somewhereb this second breaker is good insurance.

stiles watson · 09-03-2009, 05:59 AM

I am no expert, so probably shouldn't even post. The fuse is there to protect the rig. When the mechanical resistance causes amperage to exceed 30 amps, the fuse blows. Now as to why they chose to use an in-line fuse instead of an automatic resetting circuit breaker, I can't say. Some have replaced the fuse with the circuit breaker.

Different problems can cause the amperage to become excessive. A leg could be bent or failure to lubricate could cause it to bind. Once I blew a fuse be cause I forgot to loosen the stabilizer arms (like the J T stabilizers). That created too much resistance on the motor and the fuse popped which saved the motor.

Some people have replaced the 30 amp with a 40 amp. Since I really don't know the underlying reason for choosing a 30 amp, I have left it as is.

In the early days of owning this unit, we were popping too many fuses. At the Goshen rally in 2007, the Lippert guys determined that I was drawing too many amps because of poor grounding. They (Keystone) improved the quality of the ground and I haven't had fuses popping unless I have an issue causing it.

Somewhere on the low side of my priority list, I plan to make that fuse more easily accessible and/or replace it with the auto circuit breaker.

mail2us · 09-03-2009, 06:44 AM

I am at least a notch or two below Stiles in the "no expert" area but as told to us when we purchased our 2008 3400, the landing gear fuse (30 amp) may blow if you extend them beyond a point marked on our front landing gear. It indeed has happened to us once so far.

Also I believe for whatever reason as stated by ChuckD there is a beaker somewhere is correct. There are two breakers (50 amps each) on the back wall of the front compartment; one for the slides and it appears the other is for the landing gear. Beyond that, my limited knowledge takes me no further. A recent thread here indicated that 40 amp was ok due to the wire being able to handle it.Below is a previous thread on this subject. Dennis

http://www.montanaowners.com/forums/...ad.php?t=34096

ole dude · 09-03-2009, 06:51 AM

Your tech is correct that the line for the landing comes off another breaker. However this breaker is for the main line from the battery to the panel and would be too large of capacity to properly protect the landing gear motor. This is the reason for the 30 amp fuse to be added just for the landing gear motor. At least that is how mine is connected.

NCFischers · 09-03-2009, 07:05 AM

I believe all trailers have an in line fuse on the power wire to the legs. It protects against overloads. If you run the legs up too far and strain the motor, you will blow it.

bncinwv · 09-03-2009, 07:44 AM

The fuse is a good cheap form of protection for expensive landing gear motors. Not only will the fuse blow if you overextend (retract??) the legs, it will also blow if you try to lift the truck with the landing gear (NOTE #1: I will not go into this further as to how I know this), it will also blow if you try to extend the front jacks while the rear stabilizer jacks are down (SEE NOTE #1), it will also blow if you quickly reverse the motors, extend then retract or vice versa (SEE NOTE #1). I like the fuse. I like it so much that I keep about five of the suckers on hand at all times (SEE NOTE #1).
Bingo

ole dude · 09-03-2009, 08:18 AM

Bingo, don't feel like the lonesome stranger.

Dave e Victoria · 09-03-2009, 12:13 PM

As a general case, in a good system design, main line breakers are sized to protect wires. A good devise design will include device protection in the device itself. If such internal protection is not supplied then the system designer will add protection in the form of a dedicated fuse or breaker. This approach allows more than one function to be supplied power from the main line breaker.
Dave

dsprik · 09-03-2009, 01:33 PM

My OEM fuse was 40 amp coming out of the factory - build date of 7/19/06. I am not aware of a secondary breaker/fuse and I have blown that thing (see Bingo's #1) several times. I have procrastinated changing out the fuse for a 40 amp breaker...

BirdingRVer · 09-04-2009, 03:17 AM

Quote:

quote:Originally posted by NCFischers

I believe all trailers have an in line fuse on the power wire to the legs. It protects against overloads. If you run the legs up too far and strain the motor, you will blow it.

Of course the fact that there is no line or any other warning that you have run the legs too far up or down too much makes blowing the fuse inevitable. Why didn't the manufacturer just add some simple limiting switches that kill the power when you are close to the end of travel for the legs either up or down? Or at the very lease a red strip when you are getting close to the end. Anyone know how far down is too far? Is it the same for all Montanas?

Our Montana came with 40 amp fuses which are much harder to find than the 30 amp fuses. Last year the fuse was replaced with a auto reset breaker.

NCFischers · 09-04-2009, 03:23 AM

I put a ring of black tape around the landing gear leg. If I can't see a sliver of silver above the tape, I've gone too far up.

Exnavydiver · 09-04-2009, 05:41 AM

When we picked up our Big Sky at the dealer the guy that did the PDI got us hooked up and then took a black felt tip marker out of his pocket and put a mark on the leg about 1 inch from the end of the leg run. He did both top and bottom and said if we don't go past either of them we won't grind any gears or blow any fuses. I do carry many extra 30 amp fuses just in case anyway... Dave

HamRad · 09-04-2009, 07:06 AM

Our 2002 Montana came with a large sticker on the leg in white and RED.... STOP! I think we finally realized what it was for after about a year of camping!

I just figured that all Montys came with that sticker on the legs!

Dennis

bncinwv · 09-04-2009, 08:31 AM

Our legs are painted black at the top (I believe it came this way from the factory, but I may be remiss), when the black aligns, I know that is the maximum retract.
Bingo

sreigle · 09-04-2009, 08:35 AM

Sue, if yours is 30 amp, you can go to any auto parts store and buy a 30 amp auto resetting breaker with lugs that fit right in place of the fuse. It will still "pop" when it would have blown the fuse but give it a few seconds, minute at most, to cool and it will auto reset and you can continue. It eliminates the need to get in there and replace the fuse.

Ours came with a 40 amp fuse. Unfortunately, there is no 40 amp auto resetting breaker with lugs that fit right into the fuse holder. I bought a 40 amp breaker but will have to mount it to the wall, cut wires, etc. Just haven't done that yet. We've blown the fuse twice in 3 years and never on the prior two Montanas (over 5 years between them).

dsprik · 09-04-2009, 03:04 PM

Quote:

quote:Originally posted by bncinwv

Our legs are painted black at the top (I believe it came this way from the factory, but I may be remiss), when the black aligns, I know that is the maximum retract.
Bingo

We have a "dirt" line coming up, but nothing extending the legs. Does anyone know what the maximum measured distance extended is?

sreigle · 09-04-2009, 03:39 PM

Don't know the measured max length but did notice there is a point where there are no more holes to pop the pin into. At that point it's past the max usable length. Some time when hitched up maybe you can drop the leg to that point and then measure or count visible holes. I think I'll do that if I remember.

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