Circut Breaker or In-line Fuse?

[Propwash]

Hey guys...Trying to fill in some spare time while the machine shop gets done doing their thing on my engine.

I'm converting my sealed beam headlights to H1 and H4 headlamps off a relay system. Following ideas across the web, Daniel Stern and Mad Electrical, just coming across one question:

Running 10 gauge from the battery to (2) 5 pin relays with Dual 87 posts. I was thinking of running the 10 guage with in-line fuses before each relay. Other option would be to run 10 guage to a 2 post 30 AMP self reseting circut breaker and then 10 guage to the relays.

Is either one of options better/safer than the other? Cost is pretty much the same. Just want to build something that's the safest most efficient way to go. All the old wiring/plugs forward of the relays is going in the garbage can....it's pretty ratty.

Thanks

 

[Grabinov911]

Hey Prop thanks for the help in the past.

Take a look at the Painless wiring 30814. That kit is for quad H4's and uses a fuse to protect the headlight relays. They have chosen the "fuse route". They sell accessory wiring kits which provide circuit breaker protection for a series of low amperage circuits, each of which then has a fuse. So given that they have both types of systems for sale, they always seem to use the fuse with large-draw circuits and the cicruit breaker to protect a board with lots of small circuits. I believe this is because they prefer the fuse for protection of the circuit itself, and the circuit breaker for protection of the fuse BOX. This matches modern cars, where the fuse box is protected by a circuit breaker, but each circuit then has a fuse. That's how I'd do it - fuses...

Just thinking out loud...

greg

 

[snakeoil24]

Propwash I would prefer to use a fuseable link.

 

[Bruzilla]

I just did the relay install in my road runner and I just opted to keep it simple, effective, and affordable and wired in fuses between the alternator and the relays. I considered installing a two-circuit fuse block, but I could see several problems. First, the block would be mounted to the fender and exposed to the elements and they usually aren't designed for that. I was going to need to either rig up a cover or find a modern doner car, like a police interceptor, that has a good, sealed, underhood fuse block, but none of those are set up for just two or three circuits and are pretty big. So I ended up going with two basic in-line fuse holders. $2.99 each, weather resistant, and they get the job done.

 

[68 Sport Satellite]

Propwash I would prefer to use a fuseable link.

+1

Fuses blow too easy. The fusible link wires like MAD electrical specs out for things like the bulkhead connector to starter relay. Not sure what rating.

 

[super-bee_ski]

Propwash I would prefer to use a fuseable link.

X2

 

[Propwash]

Thanks for the Feedback guys! Much appreciated.

I see the fusible links are pretty cheap as well (comparable to an in-line fuse). Obviously not as easy to change out as a regular fuse, but if the link breaks I guess it's time to park it and figure out what the problem is anyways. Greg brings up a good point about the fuses and how Painless goes with them, as well as Daniel Stern's schematic. There's obviously got to be some rhyme and reason to that as well. After your thoughts and reading some more, it looks to pretty much be a horse a piece. Both have their pro's/con's.

Here's the route i'm leaning towards...Ditching the circuit breaker idea. Seems like adding one would be a bit redundant if i'm going with fusible links anyways. Running 8 Gauge wire from the positive battery to a terminal block (covered-See below). Off that terminal block, run two 9" lengths of 14 Gauge fusible link to 10 Gauge then to the the relays. Run 10 Gauge wire from each ground on the relay's back to the negative battery post. Run 12 gauge wire for the entire system forward of the relays and use ceramic weather hooded sockets to the H1/H4 bulbs. I plan on running some pretty hefty bulbs with this setup. Sick and tired of the dim substandard sealed beam old car lighting. Is this set up overkill or plenty to run the upgrades conversion?

Thanks

 

[Bruzilla]

I went around and around on the decision to get power from the battery or the alternator, as you can see on my post in the 1971-1974 forum. My issue was since power is originating from the output point on the alternator, which is connected to the battery, then it shouldn't make any difference since there isn't a second output on the alternator and there's no traffic cop switch on the alternator that says this power goes to the relays and that power goes to the battery.

In the end, I ended up connecting to the alternator for one main reason: corrosion. Even if you regularly clean your battery terminals, corrosion is still going to take its toll on any wires connected to the battery terminals, so since I didn't want to be adding to my work load by having to clean headlight wires, I went to the alternator.

As for the concept of fuses blowing too easy, that's kinda of an odd take on things that I don't quite understand. You absolutely do not want power going to a shorted wire for even a split second longer than it has to. If you've got an over-current condition, for whatever reason, you want it stopped immediately, and fuses do the best job of doing that. Fuses are cheap, like .50 cents a pop, and fast and easy to change, so why risk losing your harness or worse your car because you're afraid you might have to replace a fuse every once in a while? Seems like pretty cheap insurance to me.

 

[black64]

Thanks for the Feedback guys! Much appreciated.

I see the fusible links are pretty cheap as well (comparable to an in-line fuse). Obviously not as easy to change out as a regular fuse, but if the link breaks I guess it's time to park it and figure out what the problem is anyways. Greg brings up a good point about the fuses and how Painless goes with them, as well as Daniel Stern's schematic. There's obviously got to be some rhyme and reason to that as well. After your thoughts and reading some more, it looks to pretty much be a horse a piece. Both have their pro's/con's.

Here's the route i'm leaning towards...Ditching the circuit breaker idea. Seems like adding one would be a bit redundant if i'm going with fusible links anyways. Running 8 Gauge wire from the positive battery to a terminal block (covered-See below). Off that terminal block, run two 9" lengths of 14 Gauge fusible link to 10 Gauge then to the the relays. Run 10 Gauge wire from each ground on the relay's back to the negative battery post. Run 12 gauge wire for the entire system forward of the relays and use ceramic weather hooded sockets to the H1/H4 bulbs. I plan on running some pretty hefty bulbs with this setup. Sick and tired of the dim substandard sealed beam old car lighting. Is this set up overkill or plenty to run the upgrades conversion?

Thanks

View attachment 93695

OEM headlamp wiring has a breaker in the headlamp switch and the batt feed to the HDLP switch is protected by a fusible link. Since you are running two separate circuits to each headlamp a fuse would be safe since each side would be protected against a short. I personally would use a breaker in each line for the reset feature once the problem is fixed but either would work. The fusible link is a good ideal to protect batt feed to the relays and the fuse/breaker for protection after the relays to headlamps.

 

[TheSwede]

Why not go all the way and get a Xenon conversion?
Check my thread, page 6, it will outperform a halogen light by a light year and only at 35 watts, keeps it much cooler.

 

[747mopar]

http://www.ronfrancis.com/prodinfo.asp?number=FB-44I would avoid fusible links wherever possible. In order to open they have to literally burn in half, granted usually no problem but they can become a fire hazard "have you ever seen a picture of one as it blows, not going under my hood". I'd use a sealed fuse block or a good inline fuse holder. Ron Francis has a really good catalog that is full of pointers not to mention kits to do what you are doing, forget it when it comes to they're tech's they can't even answer a simple question.

 

[nothingbutdarts]

Run 10 Gauge wire from each ground on the relay's back to the negative battery post.
View attachment 93695

Sorry, I don't know why you would waste the 10 gauge wire from the relay ground to the battery. The only thing the ground wire on the relay does is complete the circuit within the relay to keep the coil closed. If it draws 3 amps. to do that, I would be surprised. 16 or 14 gauge max is all I would run for that. My .02

 

[black64]

http://www.ronfrancis.com/prodinfo.asp?number=FB-44I would avoid fusible links wherever possible. In order to open they have to literally burn in half, granted usually no problem but they can become a fire hazard "have you ever seen a picture of one as it blows, not going under my hood". I'd use a sealed fuse block or a good inline fuse holder. Ron Francis has a really good catalog that is full of pointers not to mention kits to do what you are doing, forget it when it comes to they're tech's they can't even answer a simple question.

Fuse links are for protection of main battery feeds into the vehicle there are no fuses large enough to handle the current without nusiance trips leaving you dead on the road. They have been used for years in OEM applications they are ment to fail open completely. They protect wiring from melting down stream. I know I did OEM wiring at Chrysler. They are underhood for a reason because of the smoke produced when they do open.

 

[TheSwede]

Sorry, I don't know why you would waste the 10 gauge wire from the relay ground to the battery. The only thing the ground wire on the relay does is complete the circuit within the relay to keep the coil closed. If it draws 3 amps. to do that, I would be surprised. 16 or 14 gauge max is all I would run for that. My .02

Right! A typical 12V relay draws 0.1-0.2 A

 

[67 B-body]

OK This applies again

A safe diagram for all to use.....
View attachment SWITCHES AND RELAYS Model (1).pdf

 

[snakeoil24]

http://www.ronfrancis.com/prodinfo.asp?number=FB-44I would avoid fusible links wherever possible. In order to open they have to literally burn in half, granted usually no problem but they can become a fire hazard "have you ever seen a picture of one as it blows, not going under my hood". I'd use a sealed fuse block or a good inline fuse holder. Ron Francis has a really good catalog that is full of pointers not to mention kits to do what you are doing, forget it when it comes to they're tech's they can't even answer a simple question.

You have a lot of fuseable links being used many more than any fuse. I would really disagree with replacing fuseable links with a fuse.

 

[67 B-body]

Remember,,, when designing a circuit you have to protect the primary conductor,,,, then look at fusing each device on the circuit with a rating that protects the device. Define the conductor size by calculating the total amp draw. Now define the fuse / breaker that protects the conductor.
I used a 10AWG multi strand copper wire in the drawing I created "shown in my previous post" You'll also notice that the switchs & relay coils are protected with a 1AMP fuse. These were ran with a smaller 14AWG wire due to the low amp draw.
I chose to design my system with a 30amp breaker that will re-set if tripped once it cools off...... I have never had it trip however...

 

[747mopar]

Fuse links are for protection of main battery feeds into the vehicle there are no fuses large enough to handle the current without nusiance trips leaving you dead on the road. They have been used for years in OEM applications they are ment to fail open completely. They protect wiring from melting down stream. I know I did OEM wiring at Chrysler. They are underhood for a reason because of the smoke produced when they do open.

I totally understand, they have been used forever with very little problems that doesn't mean that there isn't a better option. I have a lot of time and work in my engine compartment and don't to run the risk of a big black spot on my new paint. I wasn't referring to the link protecting the cars entire power source but the headlight circuit itself when I suggested a fuse "sorry for any confusion". You said there isn't a fuse big enough, this is the one I plan to use you can get them as big as 125 amp. Tell me what you think, any reason I shouldn't go this route. Here is a link to a picture of one blowing "probably an extreme case but nonetheless" oldfuelinjection.com/files/fusible-link-blow.pdf Sorry link doesn't seam to work but if you google it it will come up

 

[Propwash]

Why not go all the way and get a Xenon conversion?
Check my thread, page 6, it will outperform a halogen light by a light year and only at 35 watts, keeps it much cooler.

Couple reasons swede...1st off, I'm broke..LOL Drained, Sunk, Poor, Piggy Banks Empty, Soaked, Monetarily Disabled. I walked by a bum the other day, he gave me a quarter.
2nd off......Parts are a lot easier to come by. I can walk into any store around here and get a H1/ H4 bulb or relays. Xenon, i'd be pretty hard pressed to find bulbs, ballasts...at least around here and for now anyways. It would probably have to be ordered.


Thanks for the feedback guys. I didn't expect so many point of views, but going over the posts it's great to see angles from all sides.

 

[Bruzilla]

Let's be honest here. There's another reason why auto makers use links vice fuses - servicing. Most owners have no problem replacing fuses, but a link is a problem they are more likely to leave to a tech.

As for fuses, I've been driving around putting about 60 miles a day on the road runner with the headlights on and I haven't had a single issue with the fuses. ;)

- - - Updated - - -

Sorry, I don't know why you would waste the 10 gauge wire from the relay ground to the battery. The only thing the ground wire on the relay does is complete the circuit within the relay to keep the coil closed. If it draws 3 amps. to do that, I would be surprised. 16 or 14 gauge max is all I would run for that. My .02

If you get your relay with a plug, the plug is pre-wired with 12 gauge black wire, about 8" or so, which is more than enough to ground the relay.