40 Amp Breaker - 30 Amp Fuse?

rrcbov

At some point I figured I’d identify the circuits involved in this picture to understand the 30 amp fusing on a 40 amp breaker but I’ll be lazy for now and ask the community for it’s wisdom!   What’s going on here?

Denny16

The circuit breaker the two fused circuits probably are connected to different components. The TaB has a 40-amp DC system, and the breaker goes between the battery and the power converter 12VDC connection, as a master breaker.  The two fused circuits appear to go somewhere else, and all three are connected together on the battery side of the circuit breaker.  Our TaB400 (2018) only has one fuse in line with the circuit breaker.
cheers

MuttonChops

Disclaimers:
   -   Not a 400 Owner
   -   No 400 owner has created (as far as i know) a ACV/DCV Wiring Diagram
      (as has been done on the 320)
   -   Early year and more recent 400 builds seem to have many differences.

All that said, the picture you provided looks like an electrical circuit as shown below.

So 40A breaker would trip if both the for example Unknown and Convertor combined current was at 40A. Would assume it still has a 30-Amp shore power cord, so if WFCO has a 40A main breaker CG power pedestal circuit breaker will trip before the T@B 400 Power Center main - - - seems odd.{edit0610 AM PDT}

Really need a 400 owner to dig into what the 12VDC Power Distribution really is, based on 320 experience "we owners" need to document as NüCamp won't - - - at least publicly.

Denny16

@MuttonChops interesting diagram.  I will give my TaB400 a look to see how the circuit breaker s d fuses are tied together. Also ( not shown in rccbov’s photo) is the battery cut off switch.  Will check which one is connected to the battery and which ones are connected to the circuit breaker and if it is in parallel or series with the battery.
cheers

Sharon_is_SAM

Not sure if this helps, but, the 40A circuit breaker was placed when the new 400s came with the single 12V battery.  The 30A breaker was constantly tripping when the battery was recharged from a very depleted state.

Dutch061

I believe that on our 400 BDL that the 30 Amp fuse is from the MPPT Solar Charge Controller. However, there is only 1 in-line fuse.

Brad

MuttonChops

@Dutch061 , @Sharon_is_SAM , @Denny16 - - Thanks to All - -

I have updated the simple diagram with your observations and things are starting to make sense.

As @Sharon_is_SAM noted 40A in-line breaker was added to protect battery as (@Denny16 noted) many 400's have WFCO 8740 Convertors.  They still operate on 30-Amp shore power but can charge the battery at a 40A peak.

rhyno

I can confirm that both in-line fuses are 30 amp. One of them is definitely for the MPPT. I was pulling that fuse when working on my inverter upgrade and battery recabling projects until I figured out I could disable solar charging in the Victron app directly.

I do not know the use for the second in-line fuse.