DIY - Build and install a Bussmann RTMR Fuse/Relay Block

These kind of circuit breakers don't pop at exactly their rated amperage because they operate thermally. If you look up the specs they have over amp ratings for specified amount of times. For a non-scientific example a 200amp breaker can handle 400amps for up to 30secs (not exact specs)

 

Thanks for that. Looking at the datasheet of the 100A (Marine rated, purchasing via Connector Concepts) here (https://lib.store.yahoo.net/lib/yhst-142618731068637/187Circuitbreakers.pdf), I see at 100% load (100A), the trip time is in excess of 100 seconds. As the % of rated load increases, the trip time window decreases (makes sense). But even at 100% load, it can still be over a minute before the breaker trips, exposing the RFMR and whatnot to the excessive current. Am I understanding that correctly?

 

Correct so in that case the correctly rated breaker would be the best option.

 

Correctly rated = 80A?

 

Yep because the Bussmann box is rated for 80amp

 

Ok. That all makes sense. Thanks for explaining it for me.

 

The rating doesn't refer to the total of the fuse ratings in the bussman but the total amps that it can handle through any given assortment running at the same time. So don't kick on the 40A compressor when you already have 3 other 20A auxilary features on.

 

That much I did know, but thank you for clarifying.

 

No problem, I just posted in case you or someone didn't know.

 

I'm sure many will stumble upon it and be enlightened with your knowledge. Or, in the true forum fashion, skip the XX number of pages and post the same question.

 

I’ve noticed many people connect LINE and LOAD connections in the opposite direction. I would think there is a reason manufacturers label the BAT and AUX on the circuit breaker. I almost did the same but decided against it due safety.

 

I had the same concern and contacted Eaton about it. They confirmed that it can be installed either direction. The labels are just there as labels.

 

Okay, good to hear then

 

Neither relays nor fuses care about polarity, a relay will work with the current flowing in either direction through both the switch side and the accessory side. The bussman connects 5 of each to a common bussbar at which point it does become necessary to choose a standard but even then it's still a choice and tacozord(op) showed how to orient the relays for two different choices.

 

You’re right. I just wanted to make sure because sometimes manufacturers put in LEDs and/or snubber diodes in the circuit to protect itself from back-EMFs, to create signal lights, or any other things

 

Couldn’t find my answer in the air compressor or electrical section.
Need some advice on interpreting what I’ve got going on. Bussmann and AOB switches mounted, everything is ready to begin adding accessories.

First up is an

$338 ARB CKMA12 On-Board Air Compressor High Performance 12 Volt for Air Locker Differentials and Tire Inflation

ARB CKMA12, then a front ARB locker.
Am I correct in assuming Arb’s wiring harness is more than I need? Since The switches, relays, fuses are already in place?

I should be able to hack into the Arb harness by eliminating the wires for the ARB switch and connect the ARB harness directly to the dedicated wires I’ve labeled for the compressor (orange/black) that comes off the bussmann, is this correct?
Another question, since they include a relay and a 40a fuse, I should be able to use a ‘non relayed’ fuse from the bussmann? If it weren’t for the pressure switch It looks like I could hook power/ground directly to the bussmann but the pressure switch has me scratching my head.

 

So just speaking to the 40amp fuse requirement, Bussmann circuits are rated at 30amp max for each circuit (80a for whole shibang)

I haven’t wired an ARB tho

 

I have the same set up, well except my relay box is different. You'd want to run the pressure switch threw the bussmann and the compressor itself directly to the battery. The locker you would wire the solenoid threw the bussmann as well. basically you run power to the pressure switch, it powers the compressor. Once it reaches the psi limit the compressor will shut off, then you would activate the locker.

 

Thanks! Kinda what I was thinking, I’ll be using the stock battery until my acc battery is installed, going to clean things up a bit, I’ve no need for the second solenoid or the ARB switch. My TRD OR has the e locker outback.

 

same with mine, I kept the elocker in the back and only ended up using the 1 slot. However if you ever do want to use it its there. Things like air horn, but then you'll need an aux tank.