Three pole breaker wiring HELP, and is it safe?

[AndDavRos]

Good evening everyone!

Im hoping this is a simple question to answer, but I'm coming to naught through all my searching. I have a three pole, single 'switch' breaker in a 120V ac distribution panel I purchased from a marine consignment store (the panel says Regal Boats) and the breaker in question is the AC MAIN breaker. I want to use the panel for an auxiliary AC supply for running two space heaters this winter (it'll be enclosed, and inside, out of the weather, and wired to ABYC spec).

It looked like the panel was wired a little goofy (most notably that the neutral/white wire would not disconnect when the breaker tripped, and the neutral and ground busses were connected.

When I checked the resistance on each of the poles (closed), two read .9OHM, and one read 1.19kOHM. Everything showed open circuit when the breaker was tripped.

So, is this normal? Am I out to lunch with how this thing was wired and the resistance I'm seeing. Is it possible/standard for one pole to be used for the reverse polarity indicator?

OH! and the make of the breaker is AIRPAX, but there are no other identifying marks.

Thanks for any input you may be able to provide!!!

Cheers,
Shawn
S/V Firefly

[smac999]

I have seen a few weird 3 pole breakers where the 3rd wasn't actually a breaker. but did something with the ground wire.


you defiantly don't want the N and G connected on the boat.

[EngNate]

Sounds like you are looking at a 2-Pole breaker with a remote-trip coil, used for reverse-polarity protection on some boats. The trip coil - the high resistance set of terminals, is wired to Neutral and Ground. A hot neutral will trip the breaker. Poor neutral connections can also cause tripping of this setup, and that does help prevent fires from bad inlet connections - the neutral always corrodes first and worst. You can use either or both the breaker's poles independently of the trip coil.

[transmitterdan]

I have only seen one type of breaker like this. It was an Airpax design. There are 2 poles as a normal breaker and the third pole looks a bit different from the others. That is a trip coil. That breaker came with a 36V voltage limiting device. This connected from one of the trip coil terminals to the earth wire. The other terminal of the trip coil connected to the neutral terminal on the load side of the breaker. That would trip the breaker if connected to a dockside pedestal with hot/neutral swapped.

But this design has been discontinued I think. If you can post pictures of the breaker front and back probably it should be possible to identify it. Also, did you see any device that looks like a big diode connected to the "different looking" third pole?

[AndDavRos]

Thanks for all the info! Here is a couple of pictures of the panel:



I didn't see any diode, but there is a lamp (diode based I believe) with VERY high resistance (shows open circuit when testing with a multimeter. The lamp worked when i connected it to a power supply at 120VAC.

In lieu of using the unknown breaker I installed a Blue Sea two pole panel with separate power and polarity indications. I'll keep the funky three pole unit for future use.

How would I test the breaker for function?

Thanks again for all the info!


Sent from my iPhone using Cruisers Sailing Forum

[Lake-Effect]

Originally Posted by AndDavRos

...there is a lamp (diode based I believe) with VERY high resistance (shows open circuit when testing with a multimeter. The lamp worked when i connected it to a power supply at 120VAC.

AC indicator lights are sometimes neon, which don't start conducting til the gas ionizes at 80+ volts, so they would measure open with the average ohmmeter. If it lights on 120 vAC... it works

LED-based AC indicator lights would measure in the range of 30k or more ohms.

Originally Posted by AndDavRos

... How would I test the breaker for function?

I was going to write a nerdy dissertation on how you'd thoroughly test a breaker, but frankly...if you installed a brand-new breaker, and your connections are correct, are well-made, and the screws/terminals are all tight... the chances are very good that you won't have a problem.

If you can load the circuit to about 2/3 of the trip current, and you've got full voltage and the breaker isn't getting warm... that's 99% tested.

The other 1% is testing the trip when overloaded, but I've not yet seen a good, new breaker that failed to trip.

[transmitterdan]

Originally Posted by AndDavRos

In lieu of using the unknown breaker I installed a Blue Sea two pole panel with separate power and polarity indications. I'll keep the funky three pole unit for future use.

How would I test the breaker for function?

Thanks again for all the info!

Smart move to get a new breaker.

Interesting wiring of the first pole (top section) connecting neutral (white) and earth (green) through what seems to be a breaker section. Maybe that is a trip coil but I don't think so from the photo. I suspect this is some person's kludge that they hoped would work for that purpose. If this is in fact a 3-pole breaker as it appears then this is not an ABYC recommended setup. I would say you did the right thing by getting another breaker.