Hello,I recently wired up a 400 watt inverter near my dinette that runs directly off the battery. I did use an inline fuse rated at 40 amps but was wondering if there was any drawback to using a circuit breaker so that I wouldn't have to replace my fuse if it blew? I was thinking of installing something like this near the battery (see pic below). Is there anything electrically/scientifically stupid to doing this. I know that circuit breakers aren't as quick to act as a fuse would be, so I'm assuming the danger would be that if there were a short, would the breaker act quickly enough to stop a fire from starting?Please note I am a total newbie when it comes to electrical wiring so don't ream me too hard if I'm asking a silly question. I see everyone uses fuses for this application and I'm assuming for good reason (because they trip fast).

liquidspaceman wrote:I'm assuming for good reason (because they trip fast). Probably because a fuse is cheaper.

Just my opinion! One thing about the breaker you posted is they are auto resetting and should have a fuse protecting them, these breakers are good for circuits with motors and sometimes cause a high current on start-up or if they jam. If you do get a fault on the inverter circuit, it will keep resetting and what happens if you are not there?

In all my years as an electrician, I preferred fuses. They are cheaper to buy and they will carry the load until they blow. Unlike a CB will degrade as it is loaded to full current. Each time it trips it gets a little weaker. Then it heats up internaly and starts tripping sooner and sooner. And you can get fast acting fuses or medium blowing fuses. or slow fuses. And like the poster ahead of me said. what happens if it resets when you are not around.

Got it. Thank you everyone. I shall leave the fuse as it is.

Not so fast......My Bounder has two of these manual reset breakers (in parallel) connecting the converter and load panel to the batteries. All current, to and from, the batteries passes thru these breakers. The are now 16 years old and have never failed.If the breaker is truly the correct size for your application, install it near the battery end of the cable and forget it. It's not only acceptable, but it's quite practical.

Any Drawbacks to Using Circuit Breaker instead of Fuse?

SaltiDawg
Explorer
Jun 09, 2013
OnaQuest wrote:
Not so fast......

My Bounder has two of these manual reset breakers (in parallel) ...

No hassle intended, but everything I know screams never put breakers in parallel. Is this done commonly in RVs? (I'm not an RVer.)
mena661
Explorer
Jun 08, 2013
MEXICOWANDERER wrote:
Does any inverter manufacturer have an issue with using exclusively a "T" class fuse?
None that I know of.
MEXICOWANDERER
Explorer
Jun 08, 2013
Does any inverter manufacturer have an issue with using exclusively a "T" class fuse?
beemerphile1
Explorer
Jun 08, 2013
I use circuit breakers for essential things like the brakes. I use fuses nonessential things because a breaker can open and close indefinitely either hiding a problem or creating other problems in the case of a shorted circuit.

You may want a larger fuse than 40 amp. Typically a 400 watt inverter has a peak of 800 watts which translates to 66 amps. When I installed the 400/800 watt inverter in my RV I believe the instructions called for a 75 amp fuse. In this case it is permissible for the fuse to exceed the wire rating because the inverter will limit current to a continuous 400 watt but needs to be able to peak at higher current without burning the fuse.
MEXICOWANDERER
Explorer
Jun 08, 2013
I love to for example have a breaker rated for the load, then have a fuse rated 10% greater for security. A breaker has a Jekyll & Hyde personality according to temperature. They will carry a substantially greater amperage load when cool.

A 40 amp breaker can carry as much as 55 amps at 0C

And 30 amperes at 50C

And 20 amperes at 100C (underhood temperatures)

delcity.net has temp de-ratings for automotive type breakers.
OnaQuest
Explorer
Jun 08, 2013
Not so fast......

My Bounder has two of these manual reset breakers (in parallel) connecting the converter and load panel to the batteries. All current, to and from, the batteries passes thru these breakers. The are now 16 years old and have never failed.

If the breaker is truly the correct size for your application, install it near the battery end of the cable and forget it. It's not only acceptable, but it's quite practical.
liquidspaceman
Explorer
Jun 08, 2013
Got it. Thank you everyone. I shall leave the fuse as it is.
aruba5er
Explorer
Jun 08, 2013
In all my years as an electrician, I preferred fuses. They are cheaper to buy and they will carry the load until they blow. Unlike a CB will degrade as it is loaded to full current. Each time it trips it gets a little weaker. Then it heats up internaly and starts tripping sooner and sooner. And you can get fast acting fuses or medium blowing fuses. or slow fuses. And like the poster ahead of me said. what happens if it resets when you are not around.
MPD56
Explorer
Jun 08, 2013
Just my opinion! One thing about the breaker you posted is they are auto resetting and should have a fuse protecting them, these breakers are good for circuits with motors and sometimes cause a high current on start-up or if they jam. If you do get a fault on the inverter circuit, it will keep resetting and what happens if you are not there?
Altern
Explorer
Jun 08, 2013
liquidspaceman wrote:
I'm assuming for good reason (because they trip fast).

Probably because a fuse is cheaper.

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