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Dffraser · 10-16-2022, 05:18 PM

I sold my Class C Mallard, and I now have a 1998 Class A National Seabreeze. I installed four six volt Lifeline AGM batteries, 5100 Watts of solar, a Victron smart shunt and a Victron charge controller. I am in the process of installing a Victron Multiplus/3000 for a 30 amp system. The Multiplus has a power assist feature that could potentially add more power if needed from the battery bank while plugged into shore power, and the amps running through the Multiplus and into the 100 distribution center could exceed 30 amps. Victron recommends using 6/3 gauge wire instead of 10/3 wire, and replacing the 30 amp breaker with a 50 amp breaker. All of my circuit breakers are Thomas & Betts. The main breaker is a two pole breaker with the 30 amp main on the left and a 15 amp breaker on the right side. The Model No. is TBBD3015. T&B discontinued these breakers several years ago. T&B made a TBBD5030 and a TBBD3050 breaker. I can't find the TBBD5030 (which has the main on the left) but I found the TBBD3050. Here's my question. If I install this breaker, is it safe to change the main from being the first breaker to being the second breaker? I understand the 15 amp breaker wire will need to go to another breaker and the 30 amp breaker to the right will be unused). The second question is, I found an Eaton/Cutler Hammer BD5030 breaker. How do I determine if this breaker can be substituted for the TBBD5030 breaker as it looks identical to my existing breaker except for the amperage (and I thought Eaton bought T&B's circuit breaker business).

THenne1713 · 10-16-2022, 10:52 PM

Putting a 50a breaker in a 30a panel/ rig is an invitation to a SMOKE TEST/ FIRE TEST, AND NOT something I would entertain; your shoreline size and plug and receptacle would still be 30a unless you changed them too, and would pop first, anyway. If you want/need/ can afford a complete change to 50a, get another rig, or have a licensed electrician change it and source cords, too?

dons2346 · 10-17-2022, 10:48 AM

5100 watts of solar

Dffraser · 10-26-2022, 07:27 PM

Thanks THenne,
In order to use the power assist feature of the Victron Multiplus (I have the unit for a 30 amp rig), Victron recommends upgrading the incoming and outgoing wire from 10/3 to 6/3, which, apparently naively, I have done. And you are right, I still have a power cord which is 10/3 that needs to be spliced with the 6/3 wire that runs from the shore power junction box to the input of the Multiplus. To overcome this, I could source and replace my existing shoreline cord with a 6 gauge cord. My bigger problem, aside from the risks you identified, is that the "output" 6/3 wire from the Multiplus to my 110 Distribution Panel is too large for the neutral and ground bus bars. In addition, there is a ring shaped item attached to the panel circuit board that the main 30 amp wire passes through before it connects to the breaker that my 6/3 wire cannot pass through because it's too large. My understanding (and I acknowledge it is very limited in this area) is that the larger breaker was to accommodate a scenario where I was pulling 30 amps from shore power, but needed more amperage, which would then trigger the power assist feature of the Multiplus to supply the additional amperage from the battery bank. I didn't see the risk as you pointed out because I figured the amperage would be distributed based on the individual circuit demand, and if I overloaded an individual circuit, the circuit breaker would be activated and shut off the load feeding that circuit. Again, I admit my understanding is limited. So, aside from paying $400 for the 6/3 wire and spending hours to run the input and output wire to the Multiplus, do you suggest I remove it, use 10/3 wire and leave the main circuit breaker at 30 amps? At this stage, I was trying to figure out how I could stick with the 6/3 wire and leave the circuit breaker unchanged but then I realized I would have to make changes to the bus bars to accommodate the larger wire, and I still had the issue with the wire being too large to fit through the ring shape item on the circuit board. What do you suggest.....abandon the 6/3?

THenne1713 · 10-27-2022, 12:12 AM

Yes, I see ZERO ADVANTAGE AND ZERO NEED for the 6/3, and (potential) several hundred more $$ to even TRY to use it? Maybe you can recover 80% selling on eBay/ other, or keep for a welder or hot tub wiring project?

Dffraser · 10-27-2022, 08:49 PM

Thanks so much for the input. I was ready to remove the 6/3 wire but called an experienced RV electrician before doing so. I explained what I had done and that I was ready to remove the 6/3 and replace it with 10/3 wire. Keep in mind I have 25 foot runs for both the shore power input to the Multiplus and back to the 110 Distribution panel. This took me every bit of eight hours on my back under the RV to install. The RV electrician suggested I leave the 6/3 in place and simply add a junction box close to the Distribution panel to size down to 10/3. I can easily install a junction box about 18 inches from the Distribution panel so I bought one today and will complete the hook-up tomorrow. I agree, this is a costly and wasteful use of copper but it's already installed and the thought of another six or eight hours removing the 6/3 and installing 10/3 was not worth it to me. Thanks again to each of you who responded. Kind regards, Dan