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Hello guys,
Today i bought a 4 channel TRF M600.4AB amplifier and dont know what fuse to use for power cable. On the internet i have read that because my amp has 2 fuses 40 amps each, i have to use a 80 ampere fuse. But my amps manual says that i need to use a 40 ampere fuse. What is the right ?
 

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From an Engineering/Safety perspective, that is incorrect. You always fuse to the load, or the limits of the cable, whichever is LESS. Other than not needing to replace the fuse if you add more load, there are no advantages to running a larger fuse than required for the load. Large gauge power wires are dangerous enough as it is, don't make it worse...
 

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Swap amp fuses for 2x 30a then put a 60a fuse 3" from battery. See which ones actually pop and which don't. I think you'll be surprised at the results.
 

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From an Engineering/Safety perspective, that is incorrect. You always fuse to the load, or the limits of the cable, whichever is LESS. Other than not needing to replace the fuse if you add more load, there are no advantages to running a larger fuse than required for the load. Large gauge power wires are dangerous enough as it is, don't make it worse...
I have to disagree...

I understand your logic, and I'm not saying it's not totally incorrect. As a matter of fact; I would typically put in a smaller fuse myself.
But electrical code states that you fuse to protect the wire - not the load.

Put it this way;
Most circuit breakers in your home panel box are rated at 15amps (with the exception of your oven and clothes dryer).
The reason for this is because most circuits run a 14awg wire to them, and 14awg is good up to 15amps.
It has nothing to do with whatever the load may be at the other end.

The fuse (or breaker) is there to protect the wire - either from thermal failure due to overcurrent, or short circuit.
The load (or in our case; the amplifier) has its own internal fuses, to protect the device.
 

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You always fuse to protect the wire... not the amp.
The amp has its own internal protection fuses (which you stated are 2 x 40amp).

In your case, you would choose a fuse to protect 4awg wire, which is a 150amp fuse.
You can use any fuse size under 150amp, but not over.
exactly correct!
You will find exactly the same in every intsall rulebook be it EMMA or any other organisation.
You need to set fuse also whenever the cable crossection is changed.
 
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Probably have to agree to disagree on this one. Your car, do as you please...

You are probably electrical guy because i can see how fast you moved out from this. First one doesn't understand "electrical code" and another can't read so he choses to wave around with emma rules🤣.

Both of them didn't read part where you imply that fuse protects wire but its specification is chosen by the system.

So its 10 times safer to have 100A fuse on that "80A" amplifier cable than 140A.

Speaking of home, you would have cable that is rated to consumption following by fuse(first guy mentioned it but still culdn't see his miss.) While in car audio you have excessive selection of power cables which doesn't follow load so fuse shouldn't be chosen by the wire rating.
 

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From an Engineering/Safety perspective, that is incorrect. You always fuse to the load, or the limits of the cable, whichever is LESS.
Again, I am not saying this is totally incorrect... but since you are deferring to Engineering and Safety perspectives:

From an Engineering Perspective; You would follow the guidelines of the IEEE (Institute of Electrical and Electronic Engineers) - of which I am a member.
The IEEE guidelines read: As the definitive safety standard for electrical engineering guidelines; the National Electrical Code sets the ground rules and guidelines for practical safeguarding of utility workers and the public during the installation, operation, and maintenance of electric supply, communication lines, and associated equipment.

From a Safety Perspective; You would follow the guidelines of the NFPA (National Fire Protection Association) - which dictates and writes NFPA70 - which is the basis for the National Electrical Code.

First one doesn't understand "electrical code" and another can't read so he choses to wave around with emma rules🤣.
EMMA in Europe, or IASCA in North America draw their rulebook standards from the compliant Electrical Code in the residing country. They don't just make-up their own rules for car audio... it is a standard, based on the Electrical Code of that country.

Electrical Code is almost identical in all countries. There are slight variances, but for the most part it is a universally accepted code.
  • In the USA; the National Electrical Code is written in conjunction with the NFPA (National Fire Protection Agency).
  • In Canada; the Canadian Electrical Code is independent, but follows the same guideline principals as set-out by the NFPA.
  • In Europe; the electrical standards are created and approved by one of the three European Standards Organizations: CEN, CENELEC, or ESTI.
In all situations, the electrical code rules follow the same principal, which states that; the protection device is there to protect the wire...

National Electrical Code, Rule 240.1, states:
Overcurrent protection for conductors and equipment is provided to open the circuit if the current reaches a value that will cause an excessive or dangerous temperature in conductors or conductor insulation. The fundamental purpose of overcurrent protection (fuse or circuit breaker) is to protect conductors against the effects of excessive temperature on conductors and conductor insulation from overcurrent.

National Electrical Code, Sub-Rule 2.40.1.5, states:
Flexible cord and flexible cable shall be protected by an overcurrent device in accordance with the maximum ampacity rating of the conductor gauge and temperature rating of the insulated jacketing.
 

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I think we can all agree that overcurrent devices are meant to protect wire. I think we can all also agree that, to the extent efficiency and equipment performance involve wiring sized to minimize voltage drop, overcurrent devices sized to the load simply make good sense.
 

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Try to understand what Slave and I reply than read those rules you copy-paste, at some point you will understand what we talking about.
IF WIRE IS CHOSEN BY THE LOAD, THAN THOSE RULES APPLIES, IF THE WIRE IS EXCESSIVE FOR THE LOAD (this case and most of the time in car audio) THAN IT SAFER TO TAKE LOWER SPEC OF FUSE.

Your car and do whatever you want with it but don't share knowledge you actualy don't understand. Half of the forum have non normed power wiring-> "audio wires" so from the star you can't say "4awg is rated to 140A"... Unfortunately you can't come to my work place so i can show you how real 150A 12V DC wire looks like, feels like and its certificated datasheet.


End of story.
 

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Geez...

We're mostly splitting hairs here and talking past each other, arguing for argument's sake and to hear the sound of our own voice.

<edit>
This post was in response to a salty post today which has since been deleted. I think it still applies though, so... :whistle:
 

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Lol I choose the fuse the amp manual tells me to use except for when the wire is going from battey to battery then ill use what ever that specific wire is rated for. Some 0 gauge has more strands than others and is thicker. I used 2 250A fuses, one at each battery. But then again that's what I had so that's what I used.
 
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