Relays, Breakers, & Fuses

Alec R

Alec R

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Sep 9, 2014
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What is the difference? Does my install need a relay? Breaker? What size fuse does my equipment need and where do I put it? 

Discuss!

Please keep it clean and organized, this forum section is heavily moderated to keep information organized. We're going to use content from these discussions to compile a helpful guide for users seeking information about products in this industry.
 
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Relay is an electronically controlled switching device. Can act as a toggle switch for higher loads. Can also act as a switch to go from one load to a second without adding another feed wire, similar to how you switch from low beam to high beam.


Relays typically can handle a higher load or amperage draw than most toggle switches are rated for. 30a-50a versus 5a-20a


Breakers help protect your wire and equipment by tripping/disconnecting when a load or power draw reaches higher than its rated for.
 
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how about renaming this breakers vs fuses as relays really have nothing to do with either...
 
Fuse everything. To be honest, I've seen my fair share of "rushed" installs. You know what I mean....the kind where guys are so excited to get their lights that they rush to open the package and end up zip-tying them on the vehicle and using crap wire to run directly to a toggle switch, then directly to the battery. FUSES FUSES FUSES. Your car costs tens of thousands of dollars. A fuse costs 21 cents. Oh...and have the right tools for the job, and do the install right, every time!
 
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801 said:
Put the fuse as close to the battery as possible.
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Depending on your installation, or what you have installed. 

When i do jobs involving Smart Sirens, or Similar, i use a Circuit breaker off the battery for 75-100 Amps. then that main power feed into a Fuse block, Each fuse going to the component. One 50 AMP fuse to Smart Siren, then all the lighting within the smart siren is fused, From that fuse block i can also Fuse & hookup other components depending on their Draw. 

Radios are Always Separate. 
 
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When you want to switch something using high gauge wire and you want to use a low power rated switch.


Or if you want to tap off just about any wire that is factory because they aren't usually rated for more than they are already doing.
 
So if I have a whelen switch bow with 20 Amp fuses in it I will still need to run all my lights and siren through a seperate fuse block before I run it to the switch box correct? Where is a good place to get the fuse block I see some on Ebay but they are from China and I don't know if they are very good option thanks
 
Andrewscounty82 said:
So if I have a whelen switch bow with 20 Amp fuses in it I will still need to run all my lights and siren through a seperate fuse block before I run it to the switch box correct? Where is a good place to get the fuse block I see some on Ebay but they are from China and I don't know if they are very good option thanks
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 Your local parts store normally carries them.
 
Andrewscounty82 said:
So if I have a whelen switch bow with 20 Amp fuses in it I will still need to run all my lights and siren through a seperate fuse block before I run it to the switch box correct? Where is a good place to get the fuse block I see some on Ebay but they are from China and I don't know if they are very good option thanks
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If you are using a simple fused switchbox and a simple setup without alot of current draw, you do not need extra fuse panels and such. If you are turning on high amp equipment, you need to consider relays.

If you want a real nice, quality fuse panel, look into Blue Sea Fuse blocks.
 
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If you have a 25 amp fuse, and you have two lights that need a 3 amp fuse each and two lights that need two 3 amp fuses each, theoretically, they could all be wired to the one 25 amp fuse, right?
 
6 + 12 = 18....

20 would work.
 
If I'm using a simple LED set up with a dual avenger, a slimlighter, a pair of ion duos, and a feniex 4200 mini, if I put a fuse between the battery and the 4200 mini, should I then fuse it between the 4200 mini and each light? Or is the one fuse between the battery and the 4200 mini enough for the simple set up?
 
emt111 said:
If I'm using a simple LED set up with a dual avenger, a slimlighter, a pair of ion duos, and a feniex 4200 mini, if I put a fuse between the battery and the 4200 mini, should I then fuse it between the 4200 mini and each light? Or is the one fuse between the battery and the 4200 mini enough for the simple set up?
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A very nice controller that handles 20 Amps Max. If you put a 10 amp fuse in line after the battery ( for your existing set up) then I think you will be fine.
 
I'm looking to get a fuse block with both a common + and a common - so I can run 1 wire for each from the battery. This is the first time I will be using a fuse block.

My thought is to use a 14awg wire to power the fuse block. I'm going to place an inline fuse close to the battery, run the 14awg to the switch, and then 14awg from the switch to the fuse block. I assume 14awg is enough for my setup.

I'll be running the following lights:
2 SnM Lions
1 SnM D12
Possibly 1 SnM D6

Is 1 switch enough for this set up and load? I'm not sure what the SnM lights draw. And I'm looking at this fuse block. https://www.waytekwire.com/item/46060/ATO-ATC-Fuse-Block-6-Gang/?gclid=CK6Nt-zT_c8CFRVbhgodpsYE-g

Thanks.
 
07GD SFD said:
I'm looking to get a fuse block with both a common + and a common - so I can run 1 wire for each from the battery. This is the first time I will be using a fuse block.

My thought is to use a 14awg wire to power the fuse block. I'm going to place an inline fuse close to the battery, run the 14awg to the switch, and then 14awg from the switch to the fuse block. I assume 14awg is enough for my setup.

I'll be running the following lights:
2 SnM Lions
1 SnM D12
Possibly 1 SnM D6

Is 1 switch enough for this set up and load? I'm not sure what the SnM lights draw. And I'm looking at this fuse block. https://www.waytekwire.com/item/46060/ATO-ATC-Fuse-Block-6-Gang/?gclid=CK6Nt-zT_c8CFRVbhgodpsYE-g

Thanks.
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Running a (-) all the way to the battery is unnecessary. There are multiple grounding points you could use, without going back to the battery. 14ga Should be enough to power what you are going for, but I always lean towards going overkill/possible future expansion. I always go 125%+ of projected draw to decide on wire size.
 
Good to know about the grounding. I'll try to find a local point. I think I have a bigger gauge wire that I could use for power, just to be safe. The light heads will be wired with 14awg which seems to be plenty.

Any suggestions for the fuse size in the inline fuse as well as the block?
 
Depending on the load and the switch, you may want to look into using a relay and triggering the relay with the switch. Too much load through the switch and it could overheat/melt/destroy your world.
 
On average, LED units draw .5amps per head...or that may just be Code 3 heads...I can't remember right now...but if you figure .5amps per lighthead, you are looking at around 3amps...but only if that .5amp figure is correct
 
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