Simple, very basic AC electrical layout
- Thread starter Squidd
- Start date
And I'd agree MS
IF you need circuits (note the plural)
Putting a CB in series with another one on a SINGLE circuit is kinda dumb you have to admit and does noting to improve your safety. All assuming everything is sized properly of course.
And I'm positive 3 to 4 outlets can be put on a SINGLE circuit so you would not need more than one (no branch circuits) to accomplish what Squidd wanted to.
I will admit that we are well off the beaten track in using only one CB and one circuit. And perhaps that is the reason the code does not specifically cover it. At least I've never seen a circuit drawn out that only had one circuit. But then most AC is installed in bigger boats and houses where you would have to have several branch circuits.
IF you need circuits (note the plural)
Putting a CB in series with another one on a SINGLE circuit is kinda dumb you have to admit and does noting to improve your safety. All assuming everything is sized properly of course.
And I'm positive 3 to 4 outlets can be put on a SINGLE circuit so you would not need more than one (no branch circuits) to accomplish what Squidd wanted to.
I will admit that we are well off the beaten track in using only one CB and one circuit. And perhaps that is the reason the code does not specifically cover it. At least I've never seen a circuit drawn out that only had one circuit. But then most AC is installed in bigger boats and houses where you would have to have several branch circuits.
Bill,
Your not arguing with me, I don't write the standards.
If you had a 15A outlet & 15A double pole breaker with reverse polarity indicator then your wires would be safe, but, as John A. stated today that does not satisfy what the standard wants to see. They want to see the mains protected by a breaker and any circuits protected by branch breakers...
You'd also have to custom assemble this main breaker because companies like Blue Sea and many others sell them in only 30A and 50A versions and you should not try to protect a 15A rated outlet with a 30A breaker..
I believe you could custom order one from Paneltronics or Bass but I would guess you'll be pretty close to the cost of the basic "production" version of the main +3 Paneltronics Squid already found. I have never seen a pre-made 15A AC main breaker.
I got it MS, I'm not trying to argue. I only point out that we are doing something out of the usual. As you note Blue see sells panels to support a 30 or 50 amp service with the required branch lines since you would need at least one for the outlets and that can't be more than 15 amps so naturally you would have at least one other branch for the rest of the current. And it really makes no sense to try and sell a product that does not support the standard configuration of 30 amps.
However if we read carefully you will not find a requirement for branch lines. And admittedly that is not very smart as if you are going there then you might as well bite the bullet and go for the full service and not just a part which will require branch lines.
So if you only need one line to run a battery charger and don't intend to upgrade to add the full service then you do not need to comply with the "all branch circuits" rules as you don't have a branch circuit.
the intent of having a main and branch circuits is to protect the service (the 30 amp into the boat) and the branch lines which can total to more than 30 amps of current if you turned everything on. so you need a main to prevent going over the 30 amps and you need the lower amp CB to protect the circuits they support.
This totally makes sense to me. As does the CB where the power comes into the boat might be a distance away from the panel so if it is over 10' (think that is the value) from shore power inlet to the main breaker on the panel you need an additional one at the shore power inlet to protect the line between the inlet and the panel.
I'm just not seeing how putting a 30 amp breaker then immediate putting a 15 amp CB does anything useful. Simply putting a duel breaker main of 15 amp rating meets the rules as I read them.
Perhaps I have an odd definition of "branch circuits" and that is causing the confusion. I've read the reg and I don't recall seeing a definition of "branch circuits"
For the record if branch circuits is defined in some odd manner or the code requires all installations to support the full designed service then that would completely change things but I've never seen that anywhere. Not that it is not a good idea. But then I'm all about oddball as you well know.
However if we read carefully you will not find a requirement for branch lines. And admittedly that is not very smart as if you are going there then you might as well bite the bullet and go for the full service and not just a part which will require branch lines.
So if you only need one line to run a battery charger and don't intend to upgrade to add the full service then you do not need to comply with the "all branch circuits" rules as you don't have a branch circuit.
the intent of having a main and branch circuits is to protect the service (the 30 amp into the boat) and the branch lines which can total to more than 30 amps of current if you turned everything on. so you need a main to prevent going over the 30 amps and you need the lower amp CB to protect the circuits they support.
This totally makes sense to me. As does the CB where the power comes into the boat might be a distance away from the panel so if it is over 10' (think that is the value) from shore power inlet to the main breaker on the panel you need an additional one at the shore power inlet to protect the line between the inlet and the panel.
I'm just not seeing how putting a 30 amp breaker then immediate putting a 15 amp CB does anything useful. Simply putting a duel breaker main of 15 amp rating meets the rules as I read them.
Perhaps I have an odd definition of "branch circuits" and that is causing the confusion. I've read the reg and I don't recall seeing a definition of "branch circuits"
For the record if branch circuits is defined in some odd manner or the code requires all installations to support the full designed service then that would completely change things but I've never seen that anywhere. Not that it is not a good idea. But then I'm all about oddball as you well know.
Agree with Bill. If you have the "mains" breaker panel, if it is at- or less- than the wire capacity you're meeting the purpose if not the code. We are talking a 'smallish' boat here, not a mega yacht. As long as the work is done properly, why spend a bundle of money needlessly.
Yes as I said above you'd "technically" be protecting the wire if you used 15A double w/reverse polarity and the outlet was on 14GA wire..
But, as I have explained at length I asked the ABYC for a technical interpretation just yesterday, and it came straight from the VP and Technical Director, and they want to see the main protect the main not circuits. What Bill can't see are the minimum accepted diagrams.
And my point is that to get a custom double pole 15A main breaker, they don't sell them that way, with reverse polarity, may cost you more or darn near as close, in the end, than a commercially available pre-made main +1..
(Images, Links & Pricing courtesy Sails Marine)
Blue Sea 8077 Main Only = $69.84
Plus 15A Double Pole = $25.43
Total For Main Breaker Only = $95.27
Or
Blue Sea 8029 Main + 1 = $84.27
Additional 15A Breaker For 8029 = $10.65
Total For Main +1 = $94.92
Actually a few pennies less to get more....
We should also consider that the ABYC takes the potential for failures into account. This is why we now have both ELCI's and the AC/DC ground tie in the circuit.
Just yesterday I completely re-built a DC panel on a 1986 Ericson. In the last year I had replaced three failed breakers and they were only going to continue. The labor to do them one at a time was just getting to be quite expensive so the owner asked me to just replace them all and be done with it.
If the 15A main breaker fails to trip, and your line to the shore power inlet is not 10GA, you would then be protecting the small GA wire with the dock post breaker at 30A. Even if using a 15A double pole, and accepting that it does not technically "meet' the standard, it would be very wise to keep your inlet run to 10GA wire...
Maine,
Thanks a ton for getting to the bottom of that. From what I knew of the specs it seemed gray but now we know for sure. And you are right, there is a risk unless your outlets are rated at your full breakers rating, and that's a rare combination. Looks like a BSS 3 branch breaker panel is in my First 260's near future....
Thanks a ton for getting to the bottom of that. From what I knew of the specs it seemed gray but now we know for sure. And you are right, there is a risk unless your outlets are rated at your full breakers rating, and that's a rare combination. Looks like a BSS 3 branch breaker panel is in my First 260's near future....
I appreciate all the effort and angles we looked at here... I really don't see ever needing more than the one circut, or adding much more in AC devices as this boat will be "dry slipped" on a trailer rather than hanging in a slip.
Other than an occasional transiant visit or a bad weather weekend where "if" I launch, I may not leave the slip, I plan on anchoring out most weekends "camping style" and leaving the amenities of home...at home...
Other than an occasional transiant visit or a bad weather weekend where "if" I launch, I may not leave the slip, I plan on anchoring out most weekends "camping style" and leaving the amenities of home...at home...
Great discussion and advice. FYI, the "Blue Sea 8043 AC Main Positions Toggle Circuit Breaker Panel (White Switches)" can be picked up from Amazon.com for $185.95, slightly cheaper than the comparable unit from Paneltronics.
I think Squid found the Paneltronics main +3 for $125.00.. The 8043 is a main +3 for $185.95...