Which amp fuse to use

The green and yellow previously green wire goes to earth E. The cord clamp holds the cable securely and that both of the screws are tight. The screws holding the three plug wires are tight. The fuse is the correct size and meets British Standard BS — see the manufacturer's instructions if you are not sure what fuse to use. The fuse clips securely into its holder. It should not be loose and there should be no signs of overheating.

Replace the cover securely. How does a fuse work? Different types of fuses As a rule of thumb, fuses are rated according to the power rating of the appliance. Plugs for appliances rated up to about watts should have a 3-amp fuse coloured red.

For example: 3A Fuse — Table lamp, standard lamp, television, video, computer, mixer, blender, fridge, freezer, power drill, jig saw, soldering iron. For example: 13A Fuse — Washing machine, dishwasher, microwave, kettle, toaster, iron. One of the most important things to understand here is that wire segment A is not protected in any way.

If it were to be shorted to ground, either the wire or the battery would be damaged and in either case there would likely be an electrical fire. This is why the wire must be short. The fuse protects the remaining length of wire. This generally extends from the front of the vehicle to the back of the vehicle.

The fuse must be rated to protect the wire that's being used. The wire 'gauge' is generally the deciding factor when it comes to selecting a fuse. More information on the selection of the proper fuse will be covered on the ' Wire ' page of the site. If the amp has no fuse on-board, you will need an external fuse. If you have only one amp, the fuse at the battery can be used to protect the wire and the amplifier.

The fuse would need to be whatever was recommended by the manufacturer for the amplifier and would also need to be rated at or less than the suggested maximum current for the wire that you're using.

In the next diagram, things get a little more complicated. As you can see, wire segment 'A' is used to deliver power to the fuse within 18" of the battery. Wire 'A' is of a large enough gauge to power both amplifiers.

Fuse 'A' must be rated to protect wire 'B'. Fuse B protects wire segment C. Fuse C protects wire segment D. In most cases, the wire size is reduced at the point of distribution. ANY time that the wire size is reduced, you must add a fuse in the line at the point of distribution to protect the smaller wire. Look at the following for more detailed info about changing wire sizes. What you should know about the image below Please excuse any redundancy. This is important.

If this length of wire gets shorted, it WILL burn. Wire "B" is protected by the amp fuse. It has to be at least 4g. Smaller wire would possibly burn before the fuse would blow in the case of a short circuit to ground. This wire feeds all of the power to the distribution block. Wire "C" is supplied power from the distribution block. Since it's also a 4g wire, it needs no fuse. The main wafer fuse will protect it and the vehicle in case it's shorted to ground.

Wire "D" is a smaller wire. It's also supplied power by the distribution block. Since this wire is smaller let's say an 8g wire , the main fuse can not protect against a short circuit. If the 8g wire shorts to ground, it will burn and possibly take the vehicle with it.

This would be a very unsafe condition. Fuse "A" is protecting wire "E". If the wire is an 8g wire and the fuse is rated at 50 amps or less, the wire is properly protected in case of an accidental short circuit. Fuse "B" is protecting wire "F". The wire is a 6g wire so it can handle more current than the 8g wire. Any fuse rated at 80 amps or less will protect the wire in case it's shorted to ground.

AGU fuses aren't available for anything more than 60 amps so you'd have to have a MAXI-fuse distribution block for anything requiring more than a 60 amp fuse. AGU fuses greater than 80 amps are not available from the two 'real' fuse manufacturers Bussmann and Littelfuse. There's likely a reason for that. The fuse configuration simply isn't well suited for greater than 60 amps of current.

If you use an AGU fuse rated for more than 60 amps in a circuit that draws more than 60 amps for long periods of time, expect to have problems melted fuse holders, fuses failing but not blowing in the center of the fusible element As you can see, wire "G" is a small wire. For instance, if your amp has an internal 20 amp fuse, then you should go for a 25 or 30 amp inline fuse. Suppose you have two amps. In that case you should add those numbers together to figure out the right size for your inline fuse.

For instance, if you have two 20 amp internal fuses, then the size of your inline fuse should be more than 40 amps. This equation gives you a little more room without exposing yourself up to a dangerous situation.

Based on this info you should determine the perfect size for your inline car amp fuse. In these cases you should use a fused distribution block. A fused distribution block will protect multiple amps and other related components. Once you work out the size a fuse for your amp, the next question is the type of fuse to go for. There are a number of different types of fuses, I will summarise below:. The internal fuses of most amps are mostly some type of automotive fuse. These fuses are of the same type of fuse that is used elsewhere in your car and other audio components.

These are flat with two prongs. For instance, the head unit of the car sound system might also use this same fuse. You can use this same type of blade fuse when you install an inline fuse. The fuse is installed in the fuse holder itself. The fuse is then connected in-line with the amp power line.