Table of Contents
What size fuse do I need for 12v?
If this is for general purpose power in a car or boat, I would suggest wiring the 12 volt cigarette socket to the battery with a 20 amp fuse in the circuit. If you use a 10 amp fuse, it may not be a high enough rating for accessories such as air compressors and power inverters.
How do you size a terminal fuse?
Find the size of fuse by multiplying the amps required by the device (2) by 1.5. 2×1.25 = 2.5 then we will round up to the nearest fuse size (in multiples of 5 amps) which would call for a 5 amp fuse.
What size fuses are there?
Size groups
| Blade size | Blade group | Common ratings (maximum current) |
|---|---|---|
| Micro2 | APT, ATR | 5, 7.5, 10, 15, 20, 25, 30 |
| Micro3 | ATL | 5, 7.5, 10, 15 |
| LP-Mini (low profile) | APS, ATT | 2, 3, 4, 5, 7.5, 10, 15, 20, 25, 30 |
| Mini | APM, ATM | 2, 3, 4, 5, 7.5, 10, 15, 20, 25, 30 |
What size breaker do I need for my boat?
The ABYC says that a circuit protection device should be sized no greater than 150% of the rated current of the conductor that it feeds. And no greater than the sum of all next-in-line protection devices. A main feeder breaker that is smaller than all next-in-line downstream fuses or breakers is fine.
How many amps is a starter fuse?
The A4 starter (Delco) draws 125 amps. A 50A fuse is far too small.
How do I choose the right size fuse?
Always select a fuse size to protect the wire according to its rating. In some cases, a product manufacturer will specify a fuse value and it will usually be lower than that required for protecting the wire. If this fuse value is too high to protect the wire, use a bigger wire in the circuit.
Why do you need a 15 Amp Fuse on a boat?
Fuses are rated by amperage and are there to protect the wire from overheating and starting a fire. Fuses must be rated at the same or less rating of the wire. So if you have a wire that is rated at 15 amps you need a 15 amp fuse. This is why on bigger boats you will see many separate circuits for different systems on the boat.
How do you choose the correct fuse size?
Identify the smallest gauge wire the load current will flow through. One common misconception about choosing the correct fuse size is that it depends on the load of the circuit. However, the load of the circuit is not suitable to use alone when choosing a fuse size. The fuse size should be based on the SMALLEST wire in the circuit.
How do you size a battery bank fuse?
Lately there have been a number of questions, on this and other forums, about battery bank fuse sizing and I wanted to give a brief explanation of how I size these fuses. Simply put you size the fuse to the wire provided your wire is sufficiently sized. #1 The standard.
How tall does a blue sea battery fuse need to be?
If you’re having trouble meeting the 7″ rule then the Blue Sea MRBF fuses are excellent but they do add nearly 2″ in height to a battery post to measure your battery compartment height carefully. The limiting factor with MRBF fuses is that they only go to 300A so on bigger engines you may need a Class T or ANL.