Trying to install a new panel and very frustrated

[Cthoops]

I'll be the first to admit we don't know much about electrical wiring, but we're trying (reading the books, watching videos, etc.). At this point I'm getting extremely frustrated trying to find what is probably a simple answer.

We have purchased a Blue Sea DC Power Distribution Panel (no AC on our boat). The diagram shows that the DC positive feed needs #10 or M5 ring terminals. But we're going to need 2 AWG cables (by the way, when you get to 2 AWG size, is it automatically considered a battery cable?). I can't find 2 AWG with a #10 or M5 ring terminal anywhere. Even the custom cables at Genuine Dealz don't offer that.

What the heck am I missing? How am I supposed to do this?

[sailorboy1]

How did you decide you needed 2 AWG supply to the panel? My 50amp main D.C. Panel is supplied by a 6 awg wire. I think you have made a sizing error.

[john61ct]

Have you communicated your needs to a human at genuinedealz?

There is nothing wrong with using the maximum AWG to fit a required termination, and then "step up" to the required size for long distance current.

Step-down butt connectors, or a termination block.

[Sailmonkey]

We don't have 2awg anywhere except on the batteries!! I think you've made a sizing error

[Cthoops]

Originally Posted by sailorboy1

How did you decide you needed 2 AWG supply to the panel? My 50amp main D.C. Panel is supplied by a 6 awg wire. I think you have made a sizing error.

I used the circuit wizard on the Blue Sea website. Round trip between the panel and the battery, counting for the turns, was going to be either 2 AWG or 3 AWG.

Is there some other way to do this that I'm missing?

[Colin A]

Originally Posted by sailorboy1

How did you decide you needed 2 AWG supply to the panel? My 50amp main D.C. Panel is supplied by a 6 awg wire. I think you have made a sizing error.

Have to agree what did you base the size on? Does the panel have a main breaker? what's the amperage? My guess would be 50 or under given the #10 terminal.

ABYC E 11.8 has a load calculation you can use. You don't need to size the wire as if every load is drawing max power.

[Cthoops]

Originally Posted by Sailmonkey

We don't have 2awg anywhere except on the batteries!! I think you've made a sizing error

I will be happy if I did, because it would certainly solve my problem. But running it between the panel and the battery seems to call for 2 or 3 AWG based on the round trip distance.

I really think I'm missing something here.

[Cthoops]

Originally Posted by Colin A

Have to agree what did you base the size on? Does the panel have a main breaker? what's the amperage? My guess would be 50 or under given the #10 terminal.

ABYC E 11.8 has a load calculation you can use. You don't need to size the wire as if every load is drawing max power.

The panel does not have a main breaker. The total amperage for the panel is 100 amp. I thought I was supposed to size it as if I had everything on at the same time? Of course when I did our energy calculation (I don't have it in front of me) I believe I ended up with about 65 amps (we don't have any high-draw equipment). Maybe I should be sizing it off of the lower number instead?

[Colin A]

CThoops take a look here
https://www.paneltronics.com/atimo_s...11Excerpts.pdf
Scroll down to section E11.8 it will have the table to calculate.
If you still need a way PM me, we make some little bus bar adapters to go to 1/4" lugs that may work.

[sailorboy1]

You aren't powering an inverter through the main panel are you because other wise I don't see how you are getting 65 amps. That's a lot of load for a boat that "doesn't have high loads".

But as already mentioned you can do a step down connection

[Cthoops]

Originally Posted by sailorboy1

You aren't powering an inverter through the main panel are you because other wise I don't see how you are getting 65 amps. That's a lot of load for a boat that "doesn't have high loads".

But as already mentioned you can do a step down connection

Ah yes, I'm sorry - I don't have the paper with my calculations in front of me. I believe it was actually approximately 65 amps (maybe a bit less) over a 24 hour period running all of the instruments, radar, lights several hours a night, charging the iPads, etc.

When I get home I'll take a look at it and see what the max load would be at a given point in time. Looking at the 11.8 chart, it appears that's basically what I'm supposed to be calculating (making accommodations for intermittent usage). Then I assume I'd size the wire off of that number (plus the round-trip distance)?

[Cthoops]

Originally Posted by Colin A

CThoops take a look here
https://www.paneltronics.com/atimo_s...11Excerpts.pdf
Scroll down to section E11.8 it will have the table to calculate.
If you still need a way PM me, we make some little bus bar adapters to go to 1/4" lugs that may work.

Thanks. I've printed it out and will fill out the table when I get home from work.

[Colin A]

Originally Posted by Cthoops

Ah yes, I'm sorry - I don't have the paper with my calculations in front of me. I believe it was actually approximately 65 amps (maybe a bit less) over a 24 hour period running all of the instruments, radar, lights several hours a night, charging the iPads, etc.

When I get home I'll take a look at it and see what the max load would be at a given point in time. Looking at the 11.8 chart, it appears that's basically what I'm supposed to be calculating (making accommodations for intermittent usage). Then I assume I'd size the wire off of that number (plus the round-trip distance)?

Yeah your looking at amps at any given time (current) not amp hours (power used over time.)

[sailorboy1]

Besides not understanding (assuming this based on posts) the difference between amps and amp-hours, I seriously doubt that New panel has a 100-amp supply breaker. And the total amps of the breakers on a panel are going to add up to a lot more than what is supplied to a panel. The breakers are sized to the wire mostly not the loads and are generally oversized to limit voltage drop.

You are almost surely good to supply that panel with a 6 awg and 50 amp breaker/fuse unless the panel is far away from the batteries.

[Cthoops]

Originally Posted by sailorboy1

Besides not understanding (assuming this based on posts) the difference between amps and amp-hours, I seriously doubt that New panel has a 100-amp supply breaker. And the total amps of the breakers on a panel are going to add up to a lot more than what is supplied to a panel. The breakers are sized to the wire mostly not the loads and are generally oversized to limit voltage drop.

You are almost surely good to supply that panel with a 6 awg and 50 amp breaker/fuse unless the panel is far away from the batteries.

Yes, my knowledge is limited but I definitely understand the difference between amps and amp hours. I was thinking a bit too quickly on the 65 amps (technically I'm supposed to be working, but it's much more fun to think about the boat!), and as I mentioned I didn't have my calculations in front of me.

However, in the interest of continuing to learn, the description for the panel says that it has a maximum operating amperage of 100 amp per bus. Doesn't that mean that the panel offers the total capacity of 100 amps?