Fusing (and wire gauge) for RV DC panel

[jsalbre]

I'm installing a full system (400Ah LiFePO4, Victron Multiplus, SCC, 800w solar, etc.) and I've run into a spot I could use some suggestion on.

The factory load center is a WFCO 8955. I'm of course removing the stock converter, but I'll still be using the built in AC and DC panels. The DC panel was wired from the factory with only 8AWG line coming in, protected by a 30A breaker. That seems unnecessarily limiting to me, so I'm thinking I should size up the wiring and the breaker. The DC panel is labelled as 150A total.

The ABYC wire chart tells me that at 20' I should be good for 40A, so would folks here recommend just bumping up to a 40A breaker on my new system, or maybe go to 6AWG and use a 50A or 60A breaker?

Unfortunately I can't really say what my max combined DC load will be at this time. I've not tripped the 30A breaker, but the trailer was only used once prior to me ripping it apart, and I do plan to add additional DC loads in the future (LTE router, misc other small devices). I figured since I'm running other wiring and have to at a minimum re-route the factory wiring I may as well future-proof it.

Thanks for any input

 

[NVS]

I replaced the 8955 with the WFCO WF-8950L2-MBA. It's a 15 minute job.

Are you confusing the main 30amp AC breaker in the panel as being for DC? The DC side is all fused individual circuits. The main DC wire is fused with an ANL fuse, not a breaker.

 

[Bobert]

I would be reluctant to increase incoming amperage unless I could verify through documentation that the panel is intended for the higher amps. Rvs generally do not oversize anything.

 

[NVS]

I would add a second fuse panel if you are adding additional loads or circuits.
Similar to this.

https://smile.amazon.com/dp/B07GBST5NX/ref=cm_sw_r_apan_i_MQJV6KC31Y71K6RNCBTP?_encoding=UTF8&psc=1

 

[jsalbre]

I replaced the 8955 with the WFCO WF-8950L2-MBA. It's a 15 minute job.

Are you confusing the main 30amp AC breaker in the panel as being for DC? The DC side is all fused individual circuits. The main DC wire is fused with an ANL fuse, not a breaker.

I won’t be installing a new converter as the Multiplus will be handling the charging.

Definitely not confusing anything. There’s a 30A self resetting DC breaker on the tongue behind the battery box with the 8AWG line running from there to the DC panel. It’s going to get removed when I install my gear.

 

[jsalbre]

I would be reluctant to increase incoming amperage unless I could verify through documentation that the panel is intended for the higher amps. Rvs generally do not oversize anything.

The WFCO 8955 DC panel has “150A Maximum Current” silkscreened on to it. My last trailer had the same panel but with a 50A breaker and 6AWG going to it.

 

[NVS]

I won’t be installing a new converter as the Multiplus will be handling the charging.

Definitely not confusing anything. There’s a 30A self resetting DC breaker on the tongue behind the battery box with the 8AWG line running from there to the DC panel. It’s going to get removed when I install my gear.

That's definitely different then our motorhome is wired. I would change that then to heavier wire. I moved my lifepo4 battery to inside under the dinette seating. So it will be in more consistent temperatures.

 

[jsalbre]

I would add a second fuse panel if you are adding additional loads or circuits.
Similar to this.

https://smile.amazon.com/dp/B07GBST5NX/ref=cm_sw_r_apan_i_MQJV6KC31Y71K6RNCBTP?_encoding=UTF8&psc=1

There are 3 unused fuse slots in the existing panel, no need to add another.

 

[jsalbre]

That's definitely different then our motorhome is wired. I would change that then to heavier wire. I moved my lifepo4 battery to inside under the dinette seating. So it will be in more consistent temperatures.

Yeah, the batteries and all other equipment will be installed under the bed.

 

[corn18]

I'm installing a full system (400Ah LiFePO4, Victron Multiplus, SCC, 800w solar, etc.) and I've run into a spot I could use some suggestion on.

The factory load center is a WFCO 8955. I'm of course removing the stock converter, but I'll still be using the built in AC and DC panels. The DC panel was wired from the factory with only 8AWG line coming in, protected by a 30A breaker. That seems unnecessarily limiting to me, so I'm thinking I should size up the wiring and the breaker. The DC panel is labelled as 150A total.

The ABYC wire chart tells me that at 20' I should be good for 40A, so would folks here recommend just bumping up to a 40A breaker on my new system, or maybe go to 6AWG and use a 50A or 60A breaker?

Unfortunately I can't really say what my max combined DC load will be at this time. I've not tripped the 30A breaker, but the trailer was only used once prior to me ripping it apart, and I do plan to add additional DC loads in the future (LTE router, misc other small devices). I figured since I'm running other wiring and have to at a minimum re-route the factory wiring I may as well future-proof it.

Thanks for any input

That all looks typical for a factory install with a hitch mounted battery.

Since you are moving the batteries under the bed, you have to figure out what power you need to return to the hitch area. That can get really complex, as I discovered with my 5er.

The end state I would recommend is a 6 ga wire from the batteries under the bed to the DC load center input. A 60A fuse/CB should be fine for that. That's what I used when I moved my LFA batteries from front storage to the basement. Now you have good power to your DC load center.

Now you need to figure out what is still using power from the old location at the hitch. I was surprised to find I had a plethora of crap being run directly from the batteries up front and when I moved my batteries, none of it worked. I ran a dedicated 8ga wire back up to the front storage area and put that on a 60A fuse. It was only 6ft, so the ABYC calculator said that was fine. I used that to power a bus bar of 30A circuit breakers and hooked all the crap back up. Works great.

I hope this all makes sense. It can get baffling figuring out how everything was wired from the factory. This is my rat's nest that came from the factory:


This is what it looks like after I moved the batteries:



You can see the stuff they had powered directly from the batteries. I thought about moving all of it to the load center, but they are motor loads for the most part so they can blow fuses easily. The circuit breakers are a better match for those loads.

Here's a diagram of just my DC system:




The entire system:

 

[jsalbre]

Nice setup!

My trailer only has the tongue jack, power stabilizers, some underbody lighting, and the breakaway brake switch wired up to the front (aside from the DC load center of course). I’ve got that planned for in my diagram. I’ll post that up here when I’m actually at a computer.

 

[jsalbre]

Diagram as promised.

 

[corn18]

Diagram as promised.

View attachment 95127

Are you asking about the 6AWG wire going from the positive buss bar to the DC load center? If so, I have to give it two thumbs up because it's wired just like mine and I used the same guage wire and fuse size.

 

[jsalbre]

Are you asking about the 6AWG wire going from the positive buss bar to the DC load center? If so, I have to give it two thumbs up because it's wired just like mine and I used the same guage wire and fuse size.

Yep, that's the issue at hand

Factory was 8AWG and a 30A breaker. Seems unnecessarily small. 6AWG and a 60A makes more sense to me. It's only a 20' run.

Thanks for the confirmation!

 

[palmtreeenergy]

I'm installing a full system (400Ah LiFePO4, Victron Multiplus, SCC, 800w solar, etc.) and I've run into a spot I could use some suggestion on.

The factory load center is a WFCO 8955. I'm of course removing the stock converter, but I'll still be using the built in AC and DC panels. The DC panel was wired from the factory with only 8AWG line coming in, protected by a 30A breaker. That seems unnecessarily limiting to me, so I'm thinking I should size up the wiring and the breaker. The DC panel is labelled as 150A total.

The ABYC wire chart tells me that at 20' I should be good for 40A, so would folks here recommend just bumping up to a 40A breaker on my new system, or maybe go to 6AWG and use a 50A or 60A breaker?

Unfortunately I can't really say what my max combined DC load will be at this time. I've not tripped the 30A breaker, but the trailer was only used once prior to me ripping it apart, and I do plan to add additional DC loads in the future (LTE router, misc other small devices). I figured since I'm running other wiring and have to at a minimum re-route the factory wiring I may as well future-proof it.

Thanks for any input

Either way there is a rating for the buss and you can chose anything lower than the buss rating of the DC panel. This is why you have #8awg. Even on house main electric panels you will find the same. 125amp buss rating with 100A main or 225 amp buss with a 200A main breaker. This is 25% above the main breaker rating. There is a buss rating and there is the main fuse rating. There is also a load calculation for the total load amperage. I would stay within 80% of max amps for good safety design limits. You could go beyond the 80% but it’s a standard safety margin. This gives you some head room for surges or unforeseen increased loads.