Wire Size

[eje]

I am installing a Raymarine EV-100 WheelPilot. The installation manual says to use 8 AWG wire and a 5 amp fuse. Why such a large wire?

[Lake-Effect]

Please link us to the Raymarine install manual for your exact model of that autopilot. They're online.


Knowing the exact model, and where in the manual you found that advice, we can provide better answers.

[barnakiel]

To avoid voltage drop perhaps?


b.

[marshmat]

8 AWG is the correct gauge for a 5 amp 12 volt circuit requiring less than 3% voltage drop at 70 to 90 feet round-trip circuit length. Autopilots do not tolerate voltage drop very well.



A link to the exact place where you found that reference would be helpful.

[smac999]

the acu100 manual for wheel pilot says 10a fuse and can draw 7a

14awg 0-7m and 12awg 7-10m

page 29 and 32

https://raymarine.app.box.com/s/yvyd...e/119763483197

[Nicholson58]

You and your equipment work hard for power. Don’t waste it heating undersized wires. Especially don’t risk the performance of the driven devices. Always err oversized rather than on the margin.

[RaymondR]

The sneaky buggers tend to drop out then switch back in in standby and you drift off course when the battery voltage gets low, can lead to very scary situations if you don't catch it.

[Brian.D]

ABYC Voltage Drop Chart.

[eje]

https://raymarine.app.box.com/s/m91t...e/119763483197

Please tell me if I am reading this wrong-
The drawing on the left side of page 20 is the example I am using.
Page 27 "In-line fuse and thermal breaker ratings" says to use a 5A fuse.
Page 28 "Power distribution - sea Talking" says "The distribuiton point should be fed from the vessel's primary power source by a 8 AWG cable"

[Sailmonkey]

Originally Posted by eje

https://raymarine.app.box.com/s/m91t...e/119763483197

Please tell me if I am reading this wrong-
The drawing on the left side of page 20 is the example I am using.
Page 27 "In-line fuse and thermal breaker ratings" says to use a 5A fuse.
Page 28 "Power distribution - sea Talking" says "The distribuiton point should be fed from the vessel's primary power source by a 8 AWG cable"

You're reading it wrong. What it's saying is that the delivery point should be of at least 8 awg wire. This is to ensure that the NG network does not suffer voltage drops from an undersized feed that is also supplying other loads. for wire to the course computer you'll need to read the manual specific to that.

[eje]

Looking at the voltage drop chart, for 3% critical, 5 A - 8AWG wire wouldn't be needed until you've got a 70 ft run. I'm probably only going to have 10 ft altogether

[eje]

You're reading it wrong. What it's saying is that the delivery point should be of at least 8 awg wire.

OK, I don't understand.
There are two power wires. One to the 'Sea Talking backbone' & one to the ACU. The wire to the 'backbone' was provided in the kit. It is not 8 AWG. The power wire to the ACU was not provided. I was going to connect them both to a terminal block then run to the distribution panel. The way I read the manual ref, I should have 8 AWG wire from teh terminal block to the panel
I'll keep looking, but that was the only ref to wire size I saw.

[Montanan]

Originally Posted by eje

Looking at the voltage drop chart, for 3% critical, 5 A - 8AWG wire wouldn't be needed until you've got a 70 ft run. I'm probably only going to have 10 ft altogether

FYI:

Note that the length of run of an electrical circuit is the distance from its power source, To it load(s), plus the distance Back to its power source. Often persons get confused and only take into account one half of the circuit distance and then wonder why there is two times the voltage drop from what they thought it would be.

Do not measure the circuit run from some intermediate terminal block, i.e., an intermediate power connection, like your distribution panel, measure the circuit from its source and back to its source to determine the full voltage drop.

[Thumbs Up]

In other words, it says that if you are connecting to your distribution panel, make sure that the panel's supply is at least #8AWG. Otherwise it says you can go as small as #12-14 AWG. You will need to provide a second fused power connection for the seatalk backbone cable (unless you already have a seatalk backbone installed). The seatalk can not get it's power from the ACU100. Don't forget to put the end cap on the unused backbone connection, the system will not work without it. Raymarine's instructions are not that straightforward because it attempts to cover all models with a single manual. If you are wiring directly to the battery bank you need a 10 amp inline fuse for the ACU, and a 5 amp inline fuse for the seatalk backbone.

[Sailmonkey]

Originally Posted by eje

You're reading it wrong. What it's saying is that the delivery point should be of at least 8 awg wire.

OK, I don't understand.
There are two power wires. One to the 'Sea Talking backbone' & one to the ACU. The wire to the 'backbone' was provided in the kit. It is not 8 AWG. The power wire to the ACU was not provided. I was going to connect them both to a terminal block then run to the distribution panel. The way I read the manual ref, I should have 8 AWG wire from teh terminal block to the panel
I'll keep looking, but that was the only ref to wire size I saw.

what its saying, and badly at that, is that your panel should be fed by a minimum of 8 awg from the battery or switch or whatever its source is.

the seatalk wire should be sized for voltage drop as well as the acu supply. They don't give a wire size because that's installation dependent.