AC Circuit Breaker

Alan K · Apr 27, 2009

I have a 3-pole main CB for each of my 30-amp shore cables on my current boat and the previous one as well. Neutral and Hot account for two of the poles. I believe the third pole protects the "reverse polarity" indicator lamp. Not sure on that. I'll check my schematic when I get off the road.

Rick Webb · Apr 28, 2009

We Are Having Fun Guessing

That was not the question Blitz asked.

I'm guessing you asked these guys:

http://www.carlingtech.com/support/index.asp

Ron20324 · Apr 28, 2009

Blitz, I hope you'll keep us posted on the wiring. Inquiring minds want to know, as they say. Since the reverse light is probably just wired between the neutral and ground wires, I don't see a breaker being in there.

kloudie1 · Apr 28, 2009

Here is a three pole at Defender, but you would still have to drill the toggle holes for the other two toggles to peek through. http://www.defender.com/product.jsp?path=-1|328|296553|299262|825441&id=810907
I think the mounting screw holes are standard..

Ron20324 · Apr 28, 2009

Ah, the truth comes out !!! I think you will find that running the green ground through a breaker is not in good form. Though the boat's designer's might have thought it a good idea at the time, I believe present-day thinking (ABYS) is to not interrupt the ground that may save your life. (I assume you meant the green wired goes to it's own pole, and not the same one as the black?)

Ron20324 · Apr 28, 2009

This was over-hashed in a previous thread, so we needn't hijack this thread to do it all again, but I'll just point out my owner's manual says to not run the engine when the battery charger is on, so you'd need a handy on/off switch/circuit breaker.

Stu Jackson · Apr 28, 2009

Ron20324 said:
...I'll just point out my owner's manual says to not run the engine when the battery charger is on, so you'd need a handy on/off switch/circuit breaker.

Ron's right.

Blitz, could you please describe the color of the wires coming off the old switch, hard to see in the photos. And since you have it out, click the "handles" - I doubt if it is internally linked, but please let me know.

Ron20324 · Apr 28, 2009

Stu, the Blue Sea book says they all trip at the same time, so must turn on at the same time. So if there are two breakers (deleted info-Ron), a short/ground on one would trip both and not allow the CB to be rest until the overload is cleared. This is to prevent someone from sitting there holding the breaker in the on position, thus overriding the trip function. It's a safety thing, you know- to save us from ourselves.... Take both wires off the breakers and see if the CB can be turned on/reset (I now see he has them stripped of wires).

Ron20324 · Apr 28, 2009

Blitz said:
Left to right Top: P3 Green, P2 White, P1 Black
Left to Right bottom: P3 - empty except small wire for reverse polarity light, P2 White, P3 Black

Switch does not stay up with handle, seems like it's not catching inside.

: The internal parts can wear out, particularly if the CB is used often as a switch, which is not exactly what they are made for, though everyone uses it for a switch.

If the TOP lugs with the G/W/B are the wires from the shore power (line), I'd have to believe the AC outlets on the boat do not have ground wires since the bottom P3 is vacant of a load wire?

The plot thickens, since in that arrangement the reverse polarity light would not come on UNTIL the breaker is turned on. NOT good. But, maybe it's the BOTTOM lugs that have the shore power cord? In that case, where is the shore power green/ground? Maybe direct to engine?

Ron20324 · Apr 28, 2009

Not shown in the pictures, but might have been previously removed, is a cover over the 110 exposed circuitry. That's one of the more recent ABYC requirements, and abviously a good safety feature. Sorry to carry this on so long, Blitz, but we'd like to see you with an efficient and safe AC system. Ron

Stu Jackson · Apr 28, 2009

A little research on breaker markings & ratings

From "Understanding Circuit Breaker Markings" [http://ecmweb.com/mag/electric_understanding_circuit_breaker/]

Voltage Rating [Secs. 240.83(E) and 240.85]. Breakers are marked with either a slash or straight system voltage rating that indicates their capability to interrupt fault currents.
Voltage markings for breakers with slash voltage ratings are separated by a slash — for example, 208/120V or 480/277V. Each pole of the breaker is suitable when the line-to-ground voltage does not exceed the lower voltage marking, while the higher voltage marking is the value the line-to-line voltage may not exceed. Single-pole breakers are always slash rated.
Although the Code permits you to install a 120/240V slash-rated breaker on a 120/240V 3-phase, high-leg delta system, you cannot install it on the “B” phase (high-leg), because the nominal line-to-ground voltage of the high-leg is 208V. This exceeds the 120V line-to-ground voltage rating of the 120/240V slash breaker.
Be careful when installing slash-rated breakers on a solidly grounded high-leg delta system. Do not install them on corner-grounded, resistance-grounded, or ungrounded systems.
You cannot use a slash-rated 480/277V breaker on a 480V corner-grounded delta circuit because the line-to-ground voltage from two of the conductors would be as high as 480V. This exceeds the breaker's 277V line-to-ground voltage rating.
Two-pole breakers can be either slash or straight voltage-rated, whereas 3-pole breakers are all straight voltage-rated.

This was from a Google search on electrical circuit breaker type [http://www.mikeholt.com/mojonewsarchive/EES-HTML/HTML/ElectricalCircuitBreakers~20030621.htm] leads to the above.

Here's a good link to see the guts of a breaker: http://electronics.howstuffworks.com/circuit-breaker2.htm

Single voltage markings indicate use for grounded or ungrounded systems.

wikipedia also has a long discussion: http://en.wikipedia.org/wiki/Circuit_breaker

When the handles are connected they are called COMMON TRIP BREAKERS.

I've tried to find some specific reference for the markings shown in Blitz's earlier picture of the side of his triple breaker, but haven't found a clear one yet. Blitz or others of you may find some searching that way. Seems to be one of those "strangely hidden" things that you'd think you'd find easily. Like, "How do you read and understand he hieroglyphics on the side of a simple circuit breaker?" Maybe I'll just Ask Jeeves!!!

Blitz's circuit breaker is rated at 65A for straight 277 volts based on those markings.

My initial conclusions are

1. Only one of the three "breaker bodies" is actually physically switched in his "trio"

of breaker bodies [ed. later by Stu: wrong! see reply #48]

2. The 277 voltage is the maximum voltage that the breaker can handle, thus is good for 120V also - breaker ratings, like simple toggle switches, are good for a wide variety of voltages, while it is the amperage that is limited and needs to be specific [that is, the breaker is good up to 277 volts, 120 V will work fine] because the amperage is what we are most concerned with for breaker activation and circuit protection

3. The trip volts appears to be meaningless in this application (65V)

4. The 30 A rating is appropriate for its intended use

I recommend that it be replaced with either a single or double pole breaker, with the ground directly connected, [Ed. later by Stu: wrong - see reply #48] i.e., NOT on or through a breaker. The double pole (hot and neutral) breakers are required by the newer AYBC Code. Single pole breakers (on the hot [back 120V] leg) were fine for many years earlier. Since Blitz obviously has room behind his panel for a multiple bank breaker, he should use the newer two pole breaker. Ground does not need to be switched. The double pole breakers are NOT linked, that's why there are two "handles" and both need to be moved, one can be moved and the other will stay where it is unless moved by hand - that's why there are two of them there.

I admit I'm not a professional "electrician" but I have been interested and very involved in boat electrical systems for many years I am just simply not an expert on electrical circuit breaker markings and designations. I'm just trying to employ some of the "homework and research" that I just did in the last half an hour or so, and as I've been encouraging for a long time, and this is what I've learned from this very interesting thread.

Thanks, Blitz, we'll stay with ya on this one!

Stu Jackson · Apr 28, 2009

Polarity lights

Ron20324 said:
The plot thickens, since in that arrangement the reverse polarity light would not come on UNTIL the breaker is turned on. NOT good. But, maybe it's the BOTTOM lugs that have the shore power cord? In that case, where is the shore power green/ground? Maybe direct to engine?

Ron, the polarity lights do not usually energize until the circuit is closed, i.e., the main breaker is closed. That's because the electricity has to be flowing past the switch and if it is open (i.e., OFF) there's just no electricity for the reverse polarity indicator (RPI) to measure. The RPI is between the neutral (white) and ground (green). The RPI is usually installed downstream of the switch (main breaker). Of course, if the RPI is installed ahead of the switch, between the shorepower inlet and the main breaker, it will. "It All Depends on How It's Wired."

In any event, it really doesn't matter. Why? Because usually all A.C. appliances are OFF (or should be) before the main breaker is energized. So, if the RPI says the shorepower is incorrect, then the prudent skipper has two choices: use it or not. It is ONLY a safety hazard if you know WHY it's important. It means that the hot and neutral are wired backwards at the dock. It means that if there's a short and you're holding a tool that has a metal case and isn't grounded, you'll get zapped because the current is flowing neutral to hot instead of hot to neutral. Your boat, your choice, but your appliances WILL still work even if the RPI is lit.

There've been many "deep" electrical engineering discussions about the advantages and disadvantages of grounding the A.C. green ground to the boat ground (i.e., engine) over the years. Most production boats have kept them separate, and the green ground is simply wired direct to the shorepower ground. Without copying any of it, Calder has a very good discussion of it in his Boatowner's manual.

Ron20324 · Apr 28, 2009

Stu, I too am an advocate of the shore ground not being connected to the 12 volt "ground", i.e., engine block. The shore ground should go to a buss bar/lug to which all other AC cable grounds are connected.

In as much as the reverse polarity indicator (RPI) is there as a safety indication, I see no reason why it is not wired to make it's indication BEFORE you throw that AC main breaker. It's only a matter of wiring it on the line side of the breaker instead of the load side. Sure, most AC things will function. You just never know what might happen if the shore power is reversed and 110 allowed into the boat helter-skelter (that's an electrical term). That's why the indicator is there, and it is cheap insurance . And you use the key word that "usually" the AC appliances are off anyway. It's the "unusual" killer 110-volt situations we must protect ourselves from.

I guess my Calder's is on the boat, but I have the Boatowners Illustrated Electrical Handbook, page 170, in front of me. The only 30-amp schematic that shows an RPI shows it wired to the line side of the AC main breaker.

Ah-ha. Found the Calders's. So big and thick, I thought it was the Chapman's. Page 150 of the Calder's bible tells us the ABYC REQUIRES an RPI device to be wired in such a way as to be permanently lit or audible in the event of reverse polarity. That does not happen if it's on the load side of the breaker. Think, also, if the power is reversed, that every neutral wire on the boat is now at 110 volts via the neutral buss. Me, I think it is common sense- as per the books/abyc- to have the RPI BEFORE the main AC.

It really does matter, and that is the "why", according to the books. I suggest everyone who has replied to this thread read Calder (or anyone) who is considered the authority on this or any subject. As Stu said- and I'm not picking on him here- "Without copying any of it, Calder has a very good discussion of it in his Boatowner's manual", which is why I said the many opinions offered on critical subjects (like this one) on these forums are to be taken with a grain of salt unless the poster has recently read- and can quote- their source of knowledge.

AC Circuit Breaker

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