air conditioning circuit breaker pop

[bostonhatteras]

this problem is more annoying than anything else. every now and then the breakers to the 16k and 12k marine aire condensing units pop. we let them run 24/7 and it never seems to happen when we are on the boat so i cant really tell why it is happening. is it a voltage surge? is it a voltage drop and hence increased amperage? my question is this; how do i monitor this situation to determine what is causing the breakers to pop? a cable clamp type amperage guage would tell me the immediate situation but i think i need t look at the 'history' of what the amperage and voltage are doing over a period of days. sometimes it will go weeks without popping, sometimes twice in a week! fyi these are the hienmann breakers that are obsolete and nonreplaceable unless i rework the face of the panel. also these are full digital units and display no fault codes. thanks. like i say, more annoying than anything else Russell

[TopHattandTails]

Russell - a couple of simple things to take a look at that are not too technical (check the easy stuff first). First, what is the voltage coming into the boat (120 versus 208 versus 240)? Second, and related, take a look at the loads on the a/c legs of the voltage. If you have multiple a/c's running and are bumping up against your voltage limit (30amps for 120v or 50 amps for 240volt, or 42amps for 208 volt) they may not all have the compressors hitting at the same time (you would be fine) or as an additional compressor(s) hits due to temp / time settings (for away), you may be exceeding available voltage and thus tripping the breaker. Try setting all a/c to the max cool setting and running all at the same time and see what your amperage is. Also, with most of the digital displays, you should be able to stagger the start times (I use 5 seconds between each unit), if all units start (a higher amp draw than even run), you could spike and trip.

Obviously 1 thing to check of many...

Some other areas to look:
1) above amperage thread.
2) strainer clean (cleanliness will reduce amp draw)
3) return air filters clean (same as #2)
4) water lines clean / flushed in the past few years? (same as #2)

[Fanfare]

I have had my breakers pop from time to time. I have the original Cruisair system from 1965 although each part other than the condensers has been replaced a time or three. Therefore I don't have any fancy diagnostics or anything, but here is what I think happens. I think my AC raw water inlet is in a bad place. Port ER, just on the outboard side of the outboard stringer. The strainer is hard to reach and gets clogged a lot. Every year or so it ingests something bad, like a plastic bag, and requires diving to clear it. But more often I think it sucks a leaf or something against its external screen, stopping the flow long enough for a compressor to overheat, at which time the internal safety circuit pops the breaker. Once the breaker goes off the flow stops and without suction the leaf floats away to bother someone else, leaving no evidence.

My generator intake with its drilled hole external screen rarely has clogging problems. Nor my main engines. But my AC inlet has slots and its inside strainer. The strainer has a 90 degree bend on entrance which gathers sea grass before the strainer. The intake seems to be in just the right place for a current flowing past to push crud hitting the chine down under the surface and into the shallow entry. This system also does not prime well after hauling, requiring me to loosen its lid to release air. It's a nuisance. Why did Hatteras put this there? I think it was because of the March AC circulating pumps. These pumps are not waterproof. They are centrifugal 110v pumps designed for constant service. On my early boat if any AC is on the circulating pump is running constantly. There is no rubber impeller on these pumps. They are rigid plastic, and joined to their motor by a magnetic linkage so if the pump jambs from debris it does not burn the motor out. But this means the pump is not self priming. And because it is not waterproof the pump must be mounted higher above the bilge to prevent flooding which would ruin it. I have thought about moving the intake more toward the centerline so it could be down deeper where I think there may be less trash, but it is still under consideration. By the way, my boat came stock with two of these AC pumps installed for redundancy. Thanks Jack Hargrave! But neither works if the intake is clogged.

My boat came with three AC units. I later added a fourth and at that time rewired my panel to move all my ACs from the original single dedicated 30 amp 110v electrical line to split between both legs of a single 220v 50 amp replacement. Originally I was drawing 33 amps with the three units through a 30 amp cord and cord failure was frequent. If two units started simultaneously that would blow the breaker too.

Just one more little thing to tweak. I keep telling myself that after just 46 years on our boat we have almost everything the way we like it.

[bostonhatteras]

wow 46 years on the same boat! and i thought i was running out of projects after 13 years! those are all good suggestions. thanks. for the record, it is a dedicated 30 amp, 120 volt line that plugs into its own power post on the dock. i believe with both units running i am only pulling 20 amps or less total, not sure on start up though. i think there is a way to stagger the start ups through the settings menu, but i dont recall right now. i will let you know what i find. thanks!

[MikeP]

We had that problem when we stayed at a marina whose 240VAC was actually around 202 when measured. So it could very easily be happening due to reduced marina voltage due to loads, local power reductions, whatever. Obviously there can other reasons but with such symptoms, marina electricity is always "One of the usual suspects" to round up!

When we were at the marina I referred to, above, the only solution that allowed us to run the ac overnight was the generator.

[bostonhatteras]

Thanks for the replies. Looks like it must be the dock side that is the problem. The ac ran continuously today and no problems. Looked at the voltage meter on te ac panel quite a few times and it never was below 110. I'm happy the breakers work as designed though!

[dsharp]

The start load on the compressor is about two times the running amperage. You will have to figure out a way to keep both ac from starting at the same time. The load only last about 20 to 30 seconds but it's long enough to trip the breaker.

[bostonhatteras]

The salon ac breaker popped last night sometime after midnight. It was the only ac operating as the other was shut off at the control panel. I strongly suspect it is a dock issue. I wish I knew a way to record the voltage history. Video camera?

[nautibake]

Reviving another old thread. Seems not much really “new” that hasn’t already been addressed here!

70 amp breaker on Ships Service 2 keeps popping when AC kicks on. Swapped it with the breaker next to it, and it did the same thing. Tech thinks it might be the old version of GFI (the white switch next to the breakers). Called SAMS and Ed referred us to electrical guru. He says he is 2 months out and the parts are obsolete and can’t be replaced anyway. BTW - the pedestal is single 50 amp and does not pop. Neither do the AC breakers in the ER near the condensers.

Has anyone else already addressed this? Here are some pics. Thanks,

[KPTIM]

If the 70 amp ship's service breaker is tripping from a ground fault error (GFI) or a problem with the ground fault section of the ship's service breaker then it is natural that the dock pedestal or the ship's breaker for the AC compressor will not trip. These two breaker are not GFIC devices and will only trip in the event of high current draw.