Frequently Asked Friday

Frequently Asked Question Friday

Here at Nomadic Cooling we look to educate ourselves and our customers on all things A/C and electrical.  Our tech support is Victron trained, proficient in all things A/C and always a phone call or email away from helping our customers get the answers they seek.  Whatever we can do to help you Go Further in Comfort is our priority.  With this being said, there are questions we get frequently and would like to start addressing them here on the blog.  Feel free if you have any questions to reach out to us at

What are the right size fuses for my electrical system?

Before you go about finding the right size fuses, you should know where you need them and why.  Your electrical system is likely an expensive addition to your vehicle and an important element to your off grid experience.  In order to protect your system successfully, you should have fuses and/or breakers for circuit protection.  Installing fuses with proper fuse holders or blocks, can be a cost effective way to ensure safety in your electrical system.  Interestingly enough, the circuit breakers and fuses are in place to protect the wires or cables.  This in turn then protects the components.  Different manufacturers might have different size value ratings, so you may need to size up or down your wire or fuse.

Choosing the Fuse Amperage: 

  1. Find the Maximum Fuse Amperage by following your AWG wire size across the chart.  (Use the chart posted in the previous week's blog). Maximum fuse amperage reduces nuisance blows but offers less protections for the wire.


    • Single Wire or Bundled Wire Column, and 
    • Outside Engine Room or Inside Engine Room
  1. Calculate Minimum Fuse Amperage by multiplying product amperage rating nu 125%.  Minimum fuse Amperage provides more protection for the wire but may result in nuisance blows.  Ie: 80A x 125% = 100A
  2. Choose Fuse Amperage near the middle of this range.  Mid-range values are usually acceptable.  Consider the requirements for each individual circuit. Ie: 125A is between 100A and 150A maximum.
  3. Find available fuses by using the chart.  (Blue Sea chart)  

Utilize this chart created by Blue Sea Systems to determine the right fuse size for your electrical build.


LARGE - Fuse Selection Chart


Choosing the Fuse Holder or Block:

1. Using the same colored headings as in the steps above, follow the columns down to find fuse holders or blocks that meet your specific requirements.
2. Consider environmental factors
  • Insulating covers protect fuses from accidental shorting
  • Ignition protection is required where flammable vapors may accumulate
  • Ingress protection protects fuses from washdown or humidity
3. Decide between an in-line fuse holder or block
  • Fuse holders are compact and hold a single low-amperage fuse
  • Fuse blocks mount to a solid surface and may hold a single fuse or multiple fuses

This chart created by Blue Sea Systems is for proper fuse holders for the fuses you choose for your electrical build.

In our electrical system schematics that we designed, we put a number of fuses and/ or circuit breakers between components.  We put safety first, always, and choose to have several fail safes in place.  We recommend a Blue Sea Systems Mount 187 Circuit breaker or a fuse holder with a mega fuse to go between our air conditioner and your electrical system.  It is important to have fuses between any power source and your components.  We recommend terminal fuse blocks with terminal fuses on each battery, mega fuses in your distributor, mega fuse with modular fuse holders or mount 187 circuit breakers on your solar intake, fuses between your house battery and your DC to DC converter, a circuit breaker on both sides of your multiplus, and a circuit breaker between your smart battery protect and DC panel 8 position.

If you have any further questions regarding fuse sizing or holders don’t hesitate to reach out and let our experts guide you.