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Old 22-11-2015, 10:33   #1
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Weak breaker? Switch?

I woke up at 3 am last night to a completely silent boat. When I hopped out of bed I found the light on the 120v system off. I flipped the breaker a couple of times and then checked the main AC switch in the aft locker but nothing. There was on the pedestal and at the end of our cord but nothing in the boat.

I rigged up an extension cord and a 15 amp adapter and plugged my heater back in and went to bed. This morning I opened up the panel, wiggled some wires, flipped the breaker, flipped the switch and the plugged the boat back in and it worked.

Now as far as I remember, the main break didn't feel like it was tripped. But it was 3 am so I am not a reliable witness. And it certainly dint reset.

Adding up the draw I realized I had both 1500 watt heaters going last night (it was cold!) and of course the fridge and water heater so it is totally possible that it ended up being close to, or over, 30 amps worth of draw. But nothing was tripped and nothing would reset until this morning. Can a switch or breaker just be weak or overheat and need to cool down? Is it worth calling an electrician? (I am just dangerous enough with electricity to break things irretrievably )

Anything else I should look at?
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Old 22-11-2015, 11:48   #2
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Re: Weak breaker? Switch?

2 heaters at full blast, water heat and fridge is probably 40a...


but hopefully you don't run heaters at high.


I never run heaters at high on a boat, even if only one. see to many melted wires / outlets. run more at lower settings instead. (on different circuits)


do you have a current meter on your AC panel? if not get one.
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Old 22-11-2015, 12:02   #3
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Re: Weak breaker? Switch?

Yes, the breakers often go bad and trip too easy. Especially the type used on the old Marinetics panels and many others.. forget the name of those.
Also: Check the ends of the shore power cord, remove them and look for brown heat damage. I used to go thru a 30 amp cord one per year using 1 space heater on the boat in the PNW. You are using two and I doubt your cord is any good. BTW, you need the whole cord usually, the wires get discolored also.
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Old 22-11-2015, 18:52   #4
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Re: Weak breaker? Switch?

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Originally Posted by Cheechako View Post
Yes, the breakers often go bad and trip too easy. Especially the type used on the old Marinetics panels and many others.. forget the name of those.
Also: Check the ends of the shore power cord, remove them and look for brown heat damage. I used to go thru a 30 amp cord one per year using 1 space heater on the boat in the PNW. You are using two and I doubt your cord is any good. BTW, you need the whole cord usually, the wires get discoloured also.
Thanks. That's exactly what I wanted to know. I'll reduce the load and switch the breaker...and keep an eye on the cord.
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Old 22-11-2015, 20:00   #5
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Re: Weak breaker? Switch?

The ubiquitous 30A shorepower connectors cannot carry 30A continuously. They are actually rated for about 24A continuous. I would never load them more than that.

When they're new and bright and shiny AND if the 30A female receptacle on the dock and the 30A male connector on the boat are all bright and shiny you might get away with 30A for awhile. But not for long.

These connectors are notorious and have been for several decades. Nothing new here. Two 1500 watt heaters will together draw about 25A @ 120VAC. This in my experience is too much for a single 30A line, because the connections after a few months have almost certainly been degraded through surface corrosion, copper creep causing loose screws, etc., etc.

If you see any discoloration on the plugs or sockets, REPLACE them. Don't try to get away with a cursory cleaning.

A shore cord properly cared for and not overloaded should last several years. However, if you overload them and don't pay attention to cleanliness and snugness of connections they might last only a week or two.

Bill
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Old 23-11-2015, 10:44   #6
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Re: Weak breaker? Switch?

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Originally Posted by btrayfors View Post
The ubiquitous 30A shorepower connectors cannot carry 30A continuously. They are actually rated for about 24A continuous. I would never load them more than that.

When they're new and bright and shiny AND if the 30A female receptacle on the dock and the 30A male connector on the boat are all bright and shiny you might get away with 30A for awhile. But not for long.

These connectors are notorious and have been for several decades. Nothing new here. Two 1500 watt heaters will together draw about 25A @ 120VAC. This in my experience is too much for a single 30A line, because the connections after a few months have almost certainly been degraded through surface corrosion, copper creep causing loose screws, etc., etc.

If you see any discolouration on the plugs or sockets, REPLACE them. Don't try to get away with a cursory cleaning.

A shore cord properly cared for and not overloaded should last several years. However, if you overload them and don't pay attention to cleanliness and snugness of connections they might last only a week or two.

Bill
Thanks for that. It floors me how much more there is to learn when you go from 2 weeks a year to full time...
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Old 23-11-2015, 10:56   #7
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Re: Weak breaker? Switch?

Posted, last spring in this forum, a scary picture and description of the potential problems (actual burning in my case!) caused by old wiring and weak breakers.

Take a look to see how close we all are to smoke and flames.

See Message #11 in the following thread in this forum:

AC Main Circuit Breaker
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Old 23-11-2015, 11:12   #8
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Re: Weak breaker? Switch?

I heat with electricity when at marinas also. No way could I get by with two 1500 watt heaters and leave my hot water heater on with only one 30amp 120V shore power cord.
After seeing signs of over temp. on a newly installed 30 amp inlet on my boat I installed one of these as recommended by MaineSail.
Shore Power Cords - SmartPlug vs. 1938 Photo Gallery by Compass Marine How To at pbase.com
works great and adds great peace of mind. I've had several marina operators mention that they like seeing a boat show up with these inlets.
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Old 23-11-2015, 11:35   #9
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Re: Weak breaker? Switch?

Before I popped for a smart plug, I'd seriously consider up grading to 50 Amp if I were in your situation.
Unlikely next month or the one after that will be warmer than this one. It's getting colder
Or find a way to run at least one of those heaters off of a heavy extension cord direct to the power pedestal bypassing the boat electrical system, but two heaters on a single 30 amp is not a good idea
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Old 23-11-2015, 12:22   #10
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Re: Weak breaker? Switch?

50 amp would help but it would not be a cheap project. The cords are at least double the price. New shore power inlet. You need new breakers and new wire from the shore power inlet to the panel. And I would check that the panel is rated for 50 amp. And the wiring to the outlets with the heaters should be upped and with proper size breakers for those. Also, 50A shore power is sometimes not available for smaller slips.

If it were me I would stick with the 30A setup but make sure I did all the things recommended by the others above, especially the shower power cord. And change the breaker - one double throw 30A within a few feet of the shore power inlet (as close a possible) - not two separate breakers, in addition to the panel main breaker if there is one there too. Otherwise your wire between the shore power inlet and the panel is unprotected. Also, closely inspect the shore power inlet for heat/corrosion damage and replace it if any damage is evident. The new style connectors and shore power inlets are better but they are pricey and require both the inlet and a new matching cord.
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Old 23-11-2015, 12:41   #11
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Re: Weak breaker? Switch?

Yeah 50 ain't cheap, I briefly considered it but didn't for all the reasons exMaggieDrum said, and I don't need it, be nice maybe, but not a necessity. But then I'm never going to live in the Great White North.
I figure he is going to need a better heat source or have a long miserable winter?
None of the options are cheap I guess, but some form of burning Diesel for heat is the best as your not dependent on shorepower?
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Old 23-11-2015, 12:41   #12
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Re: Weak breaker? Switch?

Quote:
Originally Posted by Cheechako View Post
Also: Check the ends of the shore power cord, remove them and look for brown heat damage.
This was the problem on a liveaboard guy's powerboat at our dock that I was helping last year with what he called an intermittent power problem.

Come to find out, one end of the line on the shore power cord was almost burnt from it's connection probably because it was loose and arcing inside or something of this nature.

I believe it was the connection between the cord and his boat that wasn't tight enough and he was running heaters also when this occurred (the last few times). He never unhooked from the dock purposely to go anywhere so there may have been some corrosion in there also. (causing an arc)

He was thinking breakers also, but I had a meter and we proved that power wasn't getting to the breakers .....................the last time it failed for good. We were lucky that it had completely burnt through by then to get a true reading otherwise we may have still seen power at the breakers.
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Old 23-11-2015, 12:52   #13
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Re: Weak breaker? Switch?

Water heater, get in the habit of turning it on when you need it only, leave it off the rest of the time.
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Old 23-11-2015, 13:28   #14
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Re: Weak breaker? Switch?

The weather shouldn't be too bad here (average low of 0°C), I was just getting wussy. My one heater has a 600 watt mode that I had been using up until then. I will go back to low power, and probably replace the 1500 with another that has a lower rating. We just use the 2nd one to warm up the humongous aft cabin at night...hadn't realized there would be a downside to the luxury of a queen bed

All this info on cords/connections is great stuff—it isn't info I had previously come across or even an area of concern that had come up. Time for more reading...
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Old 23-11-2015, 16:24   #15
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Re: Weak breaker? Switch?

Yeah, I looked into 50 amp quite a few years ago. The cord was like $250 alone! Many powerboaters up here seem to use a double 30 amp setup. I have also seen a 50 amp to 2x30 adaptor I think. But not all docks have 50amp service anyway.
Yeah, turn the water heater off at night. It'll still be warm enough to shower in the am.
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