Fusing for comps

[Dtrom 10+ year member]

My first year in the spl scene will be next year. I already have most of my equipment. I'm running a 4k monoblock. I'm trying to figure out what size fuse(s) to use to be in the lowest street class possible, that'll stay intact through 30 seconds of music at a time. Any thoughts?

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[tommydh 10+ year member]

well Im not sure what the rules are but as an electrician if your trying to not blow a fuse I would look into what we call NO BLow fuses. Basically its a solid piece of copper

pm me with the details and i can do the calculations and find them for you

 

[tommydh 10+ year member]

2 1/0 runs with 300 amp fuses should be enuff.

 

[jteske88 10+ year member]

to get into the lowest class shouldnt he need less on the fuse rating

 

[Dtrom 10+ year member]

well Im not sure what the rules are but as an electrician if your trying to not blow a fuse I would look into what we call NO BLow fuses. Basically its a solid piece of copperpm me with the details and i can do the calculations and find them for you

No blow fuses not allowed or that would be the route I'd go lol. MECA Ohio. Think I could get away with a 200a or hopefully less?

 

---------- Post added at 09:59 AM ---------- Previous post was at 09:58 AM ----------

 

to get into the lowest class shouldnt he need less on the fuse rating

Yes sir.

 

[tommydh 10+ year member]

No blow fuses not allowed or that would be the route I'd go lol. MECA Ohio. Think I could get away with a 200a or hopefully less? 

---------- Post added at 09:59 AM ---------- Previous post was at 09:58 AM ----------

 

I use replacable link fuses alot in my shipyard stuff you can make them larger than rated but I would go Circuit breaker over fuse

 

[jteske88 10+ year member]

circut breakers are a fail waitning to happen or they dont protect anything and stick . poof flame job special

 

[tommydh 10+ year member]

for the lowest class your amp is over the limits

what is the rms on the amp? bc the class with 4000 watts you can run 3 fuses

 

[jteske88 10+ year member]

what about 2k class?

 

[tommydh 10+ year member]

what about 2k class?

If it is in the Street class

the 2k class as Im reading the book says amps up to 6000 rms 3 fuses max that is s3 in s2 you can run up to 3000 rms and 2 fuses

 

[jteske88 10+ year member]

well i have a max wattage of 2k, 1000 rms, never done comps but want to learn

 

[LosIsATool 5,000+ posts]

Trial and error.

 

[Exist_ential 10+ year member]

Circuit breakers are illegal in MECA, @Dtrom1055 ; how is your setup built? also need to know what size sub you are using.

your class is determined by how much cone area you have and how much fusing you wish to install against that cone are as well as how the setup is installed.

use this formula to determine your fusing "score" for lack of a better term. Total Amperage of In-line Fusing X 10) + Woofer Cone Surface Area

here are some examples that will help you determine.

30 amps + 2-12 = 526 40 amps + 1-12 = 513 30 amps + 1-15 = 477 50 amps + 1-18 = 754
50 amps + 1-12^2 = 644 50 amps + 2-12 = 726 100 amps + 1-15 = 1177 100 amps + 2-18 = 1509
50 amps + 2-10^2 = 700 100 amps + 2-12 = 1226 200 amps + 2-15 = 2353 200 amps + 2-18 = 2509
50 amps + 3-10 = 736 200 amps + 2-12 = 2226 400 amps + 4-15 = 4707 400 amps + 4-18 = 5018

there are also limits to how much power you can run in each class as well but i cant find it at the moment but as an example S1 is no more than 1500wrms @ amp lowest PUBLISHED ohm load, S2 is 3000wrms @ amps lowest PUBLISHED ohm load. the couple shows i went to this summer i dont think they even checked to see what power i had on tap, they just looked at my fusing to verify i was competing in the proper class BUT if you go to state or world finals they will disassemble your entire setup and look up the published specs for your equipment if they have to in order to verify you are competing legally.

 

[Dtrom 10+ year member]

[quote name='Exist_ential']Circuit breakers are illegal in MECA, @Dtrom1055 ; how is your setup built? also need to know what size sub you are using.

your class is determined by how much cone area you have and how much fusing you wish to install against that cone are as well as how the setup is installed.

use this formula to determine your fusing "score" for lack of a better term. Total Amperage of In-line Fusing X 10) + Woofer Cone Surface Area

here are some examples that will help you determine.

30 amps + 2-12 = 526 40 amps + 1-12 = 513 30 amps + 1-15 = 477 50 amps + 1-18 = 754
50 amps + 1-12^2 = 644 50 amps + 2-12 = 726 100 amps + 1-15 = 1177 100 amps + 2-18 = 1509
50 amps + 2-10^2 = 700 100 amps + 2-12 = 1226 200 amps + 2-15 = 2353 200 amps + 2-18 = 2509
50 amps + 3-10 = 736 200 amps + 2-12 = 2226 400 amps + 4-15 = 4707 400 amps + 4-18 = 5018

there are also limits to how much power you can run in each class as well but i cant find it at the moment but as an example S1 is no more than 1500wrms @ amp lowest PUBLISHED ohm load, S2 is 3000wrms @ amps lowest PUBLISHED ohm load. the couple shows i went to this summer i dont think they even checked to see what power i had on tap, they just looked at my fusing to verify i was competing in the proper class BUT if you go to state or world finals they will disassemble your entire setup and look up the published specs for your equipment if they have to in order to verify you are competing legally.[/QUOTE]

I have 2 12's. amp is monoblock rated at 4000 rms @ 1 ohm. It is wired at one ohm. Car is a 97 jimmy. No wall obviously. Enclosure in cargo area. I just want to be in the lowest class that I can legally compete in with my equipment. Metering on music.

 

[Exist_ential 10+ year member]

you are in the same boat i am this year lol. i am using just enough power to bump me out of S1 and into S2 and i will be running 1000w less than most of my opponents, you are using just enough to bump out of S2 and into S3 but you will also be using less power than most of your opponents.

The lowest possible Street class you can run is Street 3 due to your rms ratings and you will be required to run NO MORE than 100a of fusing.

Keep in mind these fuses must be within 18" of the enclosure since you are running in a jimmy.

Also make sure your box is below window line, which technically is not the window line its actually the point of the seat back that begins to transition into the headrest, or if there are no headrest its the top of the seat back. and they will get you for being even 1/4 inch over.