Blue Sea Aux Fuse Block Install

You'll need to read the specs on your fuse block to confirm what it is rated at and purchase your circuit breaker accordingly. My 12 circuit blue sea fuse block is rated at 100 amps total, 30 amps per circuit.

 

Only need one relay per accessory regardless of ignition status.

Connect your aux fuse box to the battery through a fuse or breaker rated for that fuse box.

For unswitched accessories that are always hot simply connect to one of the fuse locations and ground.

For switched accessories that are always hot connect a fuse location to a relay and use an always hot source for the relay switch* then connect the accessory to the relay output and ground. Low power items can eliminate the relay as long as the switch is rated for the accessory current.

For unswitched accessories that are hot with ignition on connect a relay to one of the fuse locations and the relay control wire to an ignition hot source.* Then connect the accessory to the relay and ground.

For switched accessories that are hot with ignition on connect a relay to a fuse location and the switch for relay control to an ignition source.* Then connect the accessory to the relay and ground.

* The same add-a-fuse can power several switches and/or relays(control side only) as it takes only ~ 1/10 A to activate a relay. This applies to relays or relay control switches only. Each relay still needs its own fused power source as does each directly switched accessory.

If you have several low power accessories at or near one location you can power a separate small fuse box with an add-a-fuse from an ignition hot source if you want them ignition hot or directly from the main aux panel if you want them always hot. I put one under the center console cup holders for relatively easy access and to eliminate several wires from the engine bay in favor of just one from the interior fuse box. Accessories powered by this panel can be switched or powered directly, just be sure the main feed wire for this panel and its fuse are sized properly(wire should equal or exceed panel rating and fuse be no higher than this). If the panel is to carry more than ~20A total consider powering it through a relay from your main panel to avoid putting excessive drain on the interior oem panel.
You can still use an add-a-fuse from the interior oem panel to make the relay ignition hot only.

While it's possible to wire everything to an engine bay fuse/relay panel sometimes it makes sense to do otherwise. While often having the relays located in one place is convenient there are times when it is more convenient to put a relay closer to whatever it controls and shortening wire runs or eliminating excessive wires through the firewall.

 

Hi guys,
Thanks to everyone that's explained so much of this so far, it's been a huge help. I'm working on adding the anytime camera mod as well as a front camera. I already have a light bar in the front bumper so I figured now would be as good a time as any to put in an aux fuse box so my wiring doesn't get too messy. It's a 2018 TRD OR.

My question is this: I want my aux box to shut off with ignition since I'm super paranoid about draining my battery when I'm out camping. I have a beefy relay to put between the breaker and the new fuse box but where do I connect that relay to for ignition control? Should I use an add-a-fuse to an existing circuit, and if so which one, or is one of the open slots in the box ignition controlled?



Please also feel free to criticize my wiring if I'm doing something dangerous.

I do have a second question about how to make the new switches in the cab light up when the headlights are on but maybe that's for a different thread.

Thanks!

 

It doesn't matter if your relays get power from a fuse box connected to the battery. As long as the switches that activate the relays are powered from an ignition only source it's simply not possible for the battery to drain through the relays unless the ignition is on and a switch is pressed. So it's not necessary to also have a relay power the entire fuse box. If you want to anyway you'll need a high capacity relay or solenoid that is activated by an ignition source and also has a feed from the battery and then on to the fuse box as well as a ground connection.

Typically the connections are:
12V connection to activate the relay
Ground for the activation side
12V main power to the relay
Output from the relay to the fuse box

This also describes common 4-pin relay connections, 5-pin relays differ only in that they can used as either/or switches as well as on/off and off/on.

For switch illumination keep in mind the switch function is mostly separate from the led function(they are separate circuits inside the housing). I say mostly because each switch usually has 2 leds, one that is always on and one the comes on with the switch(always on needs a separate 12V supply, both need ground of some sort to come on).
To have the switch illumination come on with the headlights you only need to tap into the same wire that feeds the leds on your oem switches. It's not the same as the 12V feed that supplies the actual switches since that is hot regardless of headlight condition. If you also want them to dim with your dash lights then you also need to use the dimmer ground circuit which is also distinct from chassis ground. Sounds more complicated that it really is since regardless of which way you go each switch has 4 connections:

12V power in
Accessory or relay out
Illumniation 12V in(can be either of the above, dash illumination 12V, or nothing*)
Illumination ground(can be chassis ground, dash illumination ground, or nothing*)

Illuminated whenever ignition on
Illuminated when switch is pressed
Illuminated when headlights are on(same as oem switches)
*no illumination


The baseline intensity of most aftermarket switches is much brighter than the Oem switches. It's set by a resistor inside each switch. I opened mine up and swapped out the resisiors in order to dial it down a bit. I've only dealt with the small push switches but so far I've only encountered 1/4W axial resistors in the 1K to 3K range and all needed to be upped to 10K or more(still haven't quite toned it down enough at 10K, 12k-15K is probably better). I've detailed that process in another thread as well.

 

As far as the question mark on your 100A relay goes, try this:

Add-a-fuse from ignition only source to one of the spade connections and chassis ground (battery -) to the other(pins 85 & 86). Relays are non polar so it doesn't matter which is which(same goes for 30 & 87 for main power). If you want you can route activation power through an "auxiliary power" switch for even more unnecessary redundancy. If you choose to use a switch get power from the internal fuse panel, if not use the one in the engine bay just be sure in either case that it's an ignition only source.

 

Thanks so much for the comment. I think I’ll just try adding an ignition only circuit to the main relay to cut off the aux box.

I also just learned the hard way that connecting a positive the the battery and then brushing it against my aluminum plate completes a circuit. Which makes a lot of sense in hindsight (see small crescent shape by the breaker).

Below is the test fit before I ran out of light. I’m still tinkering with hot to fit everything together.

 

Yeah, pretty much every piece of metal you see has some connection to the chassis and ground. That's why you disconnect B+ first and reconnect it last after your done waving wires around.

 

What happened to the pictures

 

Be careful on your aftermarket fuse block choice, never exceed their rated capacity. I'm shocked so many people are using these blue sea fuse blocks. And what happened to the pictures?

 

100A fuse block, 100A breaker. What's the concern?

 

Trying to get more than 100 amps through one of those fuse blocks. I wasn't referring to the OP's specific vehicle/work. I tried to find the thread (again) of something along the lines of "blue sea fuse blocks" or something like that but I couldn't find it.

 

What would you suggest as other options DG?

Any pics?

 

Ah don’t worry about it. The blue sea is excellent

 

I couldn't find one that met the application that im working on.. I'm building one from scratch to get the job done.. I'll have some pictures Friday or Saturday.

Yeah pulling 230 amps (my application) through a 100 amp max circuit breaker is a great idea. It'll be fine.

 

Thanks! I’m researching and working on putting a system together now...

 

Stop being yourself for a moment. Putting 230 amps through a 100 amp block isn’t a shortcoming of the blue sea, it’s a shortcoming of the retarded mind of the guy doing it. The blue sea is perfectly fine if used what its designed for.

 

Stop being myself?? LMAO

I didn't put 230 amps through a 100 amp fuse block so I don't know who you're writing about. I merely wrote that I couldn't find a fuse block for my application and that the blue sea fuse block is rated for 100 amps and that rating shouldn't be exceeded and you're offended somehow. ???

Drink a bottle or do whatever it is that you do and chill out.

 

This goes for any fuse box. The Blue Seas panel is rated at 100A so it can have up to a 100A main breaker/fuse. The Bussman is rated at 80A so it should have up to an 80A breaker/fuse . You won’t be able to pull more than that through the panel. Each terminal also has a maximum rating that shouldn’t be exceeded but it’s perfectly okay to have the total of all the circuits exceed the box rating. Open up the main fuse box panel on a house and it’s quite obvious that the total of all the circuits exceeds that of the panel. You’re supposed to know better than to turn everything on at once but the main breaker is there to protect the panel in case you forget.
Case in point:
Blue Seas 12-slot panel with 12-30A fused circuits fed by 4Awg wire and protected by a 100A breaker. No problem. Even though the total is 360A the main breaker will trip if the Amp draw exceeds 100A and/or each individual fuse would blow if a circuit exceeds the 30A fuse rating.
If you were planning on running more than a 100A draw simultaneously then 2 or more panels with separate breakers could be used to split the load but if not then there isn’t a problem.

 

I don't understand why you think it's ok to exceed the fuse box rating or why you don't think all accessories should be powered up at the same time. I'm fairly sure all of those circuits within the fuse panel are powered up by one internal line and that line is rated at 100 amps.

With the example that you wrote towards the end of your comment that's a failure waiting to happen for anyone that operates the vehicle and uses everything at once that's going through the fuse panel. I understand that person wouldn't be you because you understand what was built and its capacity.

A hypothetical example would be "all of my offroad lights are on right now so I have to leave my multi amplified stereo off". That doesn't make any sense to me at all. I think any and all should be able to be used at any time, but that's just me I guess.

I wasn't trying to bash anyone's setup/work. I was merely writing to not exceed the panel's rating and that I couldn't find a prefabbed fuse box for my application. I regret commenting in this thread and I should have had more patience to find the actual thread that I wanted to comment in.

 

You don’t exceed the fuse box rating in the truck the same way you don’t do it in your house. There are enough outlets and circuits to plug in more devices than your house’s main panel is capable of supplying. You simply don’t turn them all on at the same time. If you did the main breaker would trip and the entire house goes dead. But it still doesn’t burn to the ground because the main breaker is sized to the main panel. It doesn’t matter that your 100A panel with its 100A main breaker has 6-20A breakers, 6-15A breakers, and paired 30-A breakers for an oven or dryer, they aren’t all on at the same time. If they are then you need a bigger panel, or in the case of our trucks an additional one, which is what I suggested.
If you have a just a few high drain devices then consider separating them from the panel with their own fuse/breaker and/or high current relays if you want them switched.
You need to figure out what the current draw of your lights and amplifiers are and design the electrical system accordingly. If you don’t your party will be a flop.
You need to read more and panic less. Don’t regret posting, just learn a bit more about it. I suggest the op on this thread could help you figure it out.
https://www.tacomaworld.com/threads/diy-build-and-install-a-bussmann-rtmr-fuse-relay-block.399454/
If one panel won’t be enough, use two. Many of these systems are put together by members where there’s no intention of using all the circuits simultaneously so there’s no risk of overload but even if some drunk boob flipped all the switches the breaker could be reset with no harm done. If you plan on having that party you should design your system to include a few extra batteries and an isolator or that “in excess of 100A” load is going to leave you stranded as well.
My own has an 80A Bussman along with two individually fused 40A relays for additional circuits that exceed the 30A individual circuit rating of the Bussman.