View Full Version : Max current load to accessory breakers?

05-04-2014, 03:37 AM
Can anybody tell me the max current capacity for the feed to the breakers under the dashboard on a 2000 xstar? There is a spare 20A breaker that I was going to feed a new jabsco pump from, however wondering if I am getting close to the feed cable limit. The alternative is to run a separate cable direct to this breaker (and the other spare)

05-04-2014, 07:31 AM
Basic principal would suggest that the cabling with a 20A breaker would handle more than 20A. Do you know what size the cable is? A 20A beaker for a Jabsco, but would want to know the size of the cable feeding. If in doubt, run a new B+ from the helm BUSS feed to the breaker.

05-04-2014, 09:02 AM
Sorry, I should have been more specific. The feed supplies multiple breakers. I haven't looked too closely but given that some accessories work I dependant if the Perkins switch. There are two feeds, one switched, one not. I would hope mastercraft would have specd the cabling to handle the entirety of the breakers, however not something g to assume . Guessing some more investigation required .....

Jeff d
05-04-2014, 09:12 AM
Those acc switches are normally SPST (I.e. Two position "On-Off"). Typically with ballast pumps you need SPDT or DPDT (I.e. 3 position, "On-Off-On"). Also, with the reversible Jabsco pumps you'd need a relay arrangement to reverse the polarity to the pumps to make them fill in one switch position and drain in the other. In that arrangement you wouldn't have much of a load at all on the actual switch as the relays would be handling the current necessary to run the pumps.

Jeff d
05-04-2014, 09:24 AM
My above statements about the relay arrangement were if you were duplicating/modifying the typical OE setup that master craft uses for the reversible pumps. You can wire the ballast puppies straight up to a 3 position switch if you have sufficient gauge wiring.

I think they max amperage for a ballast puppy is around 11 amps so if you're running two you're around 22 amps or so. I think you'd be safe with the factory wiring to the switch cluster. It would be pretty easy to run a new 10 gauge wire from the +12v bus bar to your two breakers for those switches though if you wanted to. It's usually less than a foot away from there. Just run a 10 gauge jumper from the bus bar to the first breaker and then a short 12 gauge jumper to the second breaker. From there you could run 12 or 14 gauge wire to the pumps depending on the distance. If they're back by the engine I'd use 12 gauge or better.

05-04-2014, 10:18 AM
Thanks Jeff, I'm comfortable with the wiring and switching I'll be running - 40A to give some future proofing for additional pumps etc a 3psn switch on the dash. I was however a little worried about the feed wire to the breakers. There are two "banks" of breakers, one switched via the perko, the other unswitched. I've got an old photo of the electrics and it looks as if each "bank" of breakers is fed with a 12awg cable (so around 30-40A max depending on length, wire grouping etc). Now the sum total of each bank of breakers is above that of their feed cable so potentially I could burn out the feed cable before the breakers pop. Think, to be safe, I'll run a fused 10mm2 cable to the unswitched bank and increase the gauge of the jumper cable between the breakers accordingly (What MC should have done in the first place).