Catalina 320 electrical issue

[Ted10028]

I was running heat pump for heat, plus 400 W electric heater. It blew the main 30 amp breaker on the boat. Both heaters went off but not the cabin lights? Apparently the main breaker does not control everything on the boat or maybe it switched automatically to batteries for some circuits when main blew?
Also wondering how 2 heaters could have blown 30 amp breaker unless heat pump uses 25 amps or so?
Does this mean heat pump would not run with just batteries ie , without shore power or Yanmar generator/alternator on??

 

[dlochner]

The cabin lights run on DC are always powered by the batteries.

Unless you have a really large battery bank, the heat pump and the AC electric heater were running on AC. If the batteries are less than completely charged the battery charger was also running. The combined current draw exceeded 30 amp.

 

[Scott T-Bird]

The electric heater could have been drawing more amps than you think - who knows how much resistance they have after being banged around and who knows what lies they tell on their spec sheets. What kind of heat pump do you have? Running the heat pump, an electric heater from an outlet, a battery charger & perhaps you had your water heater on & starting to heat water and perhaps some other appliance from an outlet ... it's not that hard to set off the AC breaker. Where did the breaker trip? On board or at the pedestal? You may have a breaker that is ready to be replaced. It shouldn't be hard to find the weak point. Catalina didn't put an AC voltmeter or ammeter on our boats. These are 2 additions I intend to install. BTW, everything on the DC panel isn't going to trip from an AC trip as long as the batteries have any kind of charge.

 

[LloydB]

Even small heaters use more current during startup mode (begin heating) than during running. When the thermostat commanded two heaters to begin heating at the same time and other electronics were also operating such as the inverter it's not so surprising. Have you checked the filters on the heat pump to make sure that they're not somewhat impeded?

 

[Stu Jackson]

Ted, you should do some reading on boat electrical systems and basic loads and currents. When a breaker pops, as you must realize, it's because the load on it exceeds its rating. A 1500 watt heater, like most small space heaters and also the coil in your water heater draws 15 Amps, AC (alternating current - shorepower). An easy way to remember this is watts / volts, 1500 watts / 100 (nominal volts AC is 120V) = 15A. Go from there.

Charlie Wing's Boat Electrical Systems is a good starter book. Calder's Boat Mechanical and Electrical Systems is "heavier" and covers lots more stuff, all of which you'll need to learn.

Good luck.

 

[Ralph Johnstone]

In addition to the above, check that your 30A AC breaker does strip at 30A.

I recently replaced a 15A AC breaker which was tripping closer to 12 after 23 years. During winter time, it passed current for a 1500 W heater to take the chill of the boat when working on projects. The heavy loading may have contributed to its demise.

 

[Stu Jackson]

Ralph's right. Another thing to check is the connections of the AC wires to the breaker inside your panel. A number of years ago I was doing some work on the DC side of my panel and looked over and saw some very disturbing scorch marks on the bodies of the connectors of the wires to my main AC breaker. i replaced the connectors and adjoining wires immediately. The breaker was and still is fine.

 

[Ted10028]

thanks guys. I guess cabin lights, 400 watt heater, heat pump, refrigerator, possible water heater and battery charger must have been too much.