PD4045 branch fuses

[Dalorin]

All,

The PD4045 has two branch ratings, black wires are for 20 amp max and red for 30. Should I use fuses of those sizes or should I under size them to be safe?

Thanks in advance

[noseoil]

Fuses (breakers) are there to protect the wiring, not the device or appliance attached to the wire. Your wire size should always withstand the load attached to it, & the fuse should always go before the wire is hot.

[Dalorin]

@noseoil, I concede that ordinarily that may be the case when run just from a battery, however, in this situation the charge controller could be delivering the load. So it's protecting power system circuitry as well.

I'm using 12awg stranded speaker wire throughout. So I'm pretty confident it will handle a 30 amp load across a max 20 ft length of wire.

[MtnDon]

12 AWG wire is usually limited to 20 amps

http://www.cerrowire.com/ampacity-charts

[Dalorin]

Fair enough. 20 amp. I'll just run the 30 amp lines to sockets in the galley on 10awg. That's only a couple feet anyhow.

My question on the fuse ratings still stands. I guess I'll call progressive dynamics.

[Dalorin]

I just got off the phone with progressive dynamics. They said that you can use up to 30amp fuses on the 30 amp lines and up to 20 on the 20 amp lines. However, they did suggest sizing it for the load.

I have a fan vent that should not draw more than 2 amps. I'm likely to put a smaller fuse on the vent. Also likely to use smaller fuses for my lights.

[noseoil]

Here's a chart which may be useful. Most of my loads will just use 5 amp fuses, since LED lighting draws such a small amount of current. The biggest load I have is really just the chargers at the headboard for phones, about 2 amps X 2 outlets or total possible load of 4 amps at 14', if both phones need a charge at the same time. 18 gauge wire is plenty for LED's & relatively small loads.

The high power load runs off of a 110v inverter & feeds the galley outlet on wiring which is stranded 14 gauge house type wire. The entertainment system also runs from the inverter. The PD4045 supplies shore power for the front-mounted AC & another galley outlet at the counter. I'm not going to bother to try to power the AC with the battery, as it doesn't have enough capacity to run for long enough with the load the AC creates to do any good.

[Dalorin]

@noseoil Thanks! That is helpful.

[Shadow Catcher]

Yes the wiring into the PD is 20A what you attach to that may not be. 14 ga was used in our tear and while you are protecting the wiring why not protect what is attached to it as much as practicable.