My 1999 Mk II does not have a fuse in the 9 inch 10 gauge line between the common terminal of the battery switch and the many circuit breakers on the electrical panel. I have noticed that this is a common feature on more contemporary boats. Any views on whether this would be a necessary or prudent addition?
Unless that wire is in some for of protective conduit between the "C" post and panel it requires a fuse to meet the safety standards. That is unless the entire system is wired with 10GA and there is a fuse at the battery.
Any time you step down in wire size the larger wire size you stepped down from is essentially your "source". The fuse goes at the step down point to protect the smaller wire. If the fuse supplying the large feeder wire is small enough, to adequately protect 10GA wire, then no additional fuse would be required.
This is one of the most widely violated over-current protection violations in regards to ABYC standards. If your battery bank has a 250A to 300A fuse, and it should, then you can't protect 10GA with those fuses.
Quote from: John Langford on May 25, 2017, 02:37:30 PM
My 1999 Mk II does not have a fuse in the 9 inch 10 gauge line between the common terminal of the battery switch and the many circuit breakers on the electrical panel. I have noticed that this is a common feature on more contemporary boats. Any views on whether this would be a necessary or prudent addition?
John.
I am going to disagree with RC on this one. Based on both ABYC but especially my "common sense code."
The "encased in a sheath ... or conduit exception" pertains to the LOCATION of the fuse -- NOT whether or not you NEED a fuse.
In this example, if the wire is protected, the fuse needs to be "as close as practical" but not more than 40-inches from the power source (C post of the switch.)
Being a wire supplying power to a panelboard, there must (no exception) be a fuse @ no more than 100% of the wire capacity AT THE SOURCE of the power to the panel (ie, the C post). No exceptions to that (e.g., not for the wire being encased/protected, or being less than 7" long, or being sized 10 times larger than the needed capacity, etc.)
That also passes my "common sense rule" -- Why?
Because it's feeding a panel, there's a possible scenario where the entire panel circuits could draw more than the safe capacity of the
10 awg power feed wire. Whether or not the feed wire is protected in a conduit (protecting it from harm) is irrelevant -- the concern is not damage to a wire behind a panel, it's over current and exceeding it's capacity. You wouldn't want it over current, and melting the insulation, even if it's in a sheath. Plus, being in a sheath the situation is worse (no air circulation, temperature rise) in melting the insulation.
That's my story and I've got a sticking Toit. ;-)A fuse wouldn't be needed there if the feed wire was the same gauge as your battery cable AND all panel jumpers were the same (if fuses/breakers are not on a buss) AND your battery was fused (within 7-inches.)
An aside - One thing I did was feed my (way old style) panel w/ 2 banks of switches/fuses from both ends to reduce V loss. There was inherent v loss with every jumper wire and terminal as power hopped from switch to switch.
ken
Ken,
Your points are good but I suspect you missed a point in regards to how Catalina looks at this.. It is a 9" long wire because the battery switch is physically mounted in the DC panel board.. Catalina is likely trying to skate around the ABYC standard by considering this a "pigtail of less than 7"". IMHO this is an incorrect interpretation/application, but the standards need a lot of tightening up of wording.
There are three general options:
1 - In general (not applicable to far too many Catalina's), if it is a "7 inch or less pigtail" or short jumper you could put it it in a protective sheath or conduit so long as the main DC panel breaker (most Catalina's don't have a panel mounted DC Main Breaker) is not going to allow you to overdraw the wires max ampacity of 60A. The 10GA is likely suitably sized to meet the 3% max voltage drop requirement, but not appropriate per the standards, for more than 60A, regardless of length.
In this situation, due to the very short length, it is unlikely that 3% VD would be the issue, but pushing the wire beyond it's max ampacity of 60A in free air could be. The DC panel on our 36 footer is fed by 1GA wire and fuse at the "source" and the panel has a DC Main Breaker of 100A... This option only works it you have a DC main breaker at the panel and most Catalina's do not. Later Catalina's used 6GA & occasionally 4GA pigtails between the "C" post and breaker busbars but still no breaker and non-complaint OCP..
2- Add a fuse at the "C" post or a DC main breaker within 7" of the "C" post. This is really the only option when Catalina does not offer a DC Main breaker.
3- Best - Install larger wire and a fuse at the "C" post or add a DC main breaker.
Like many other builders Catalina cuts a lot of corners with electrical systems. They place battery switches in AC / DC panels, perhaps to avoid having the added expense of a "DC Main Breaker", yet they then violate the part of the standard that requires battery switches to be as close as practicable to the batteries. What they save in main breaker expenses they more than eat up in wire costs. The wiring on our 2005 C-310 was atrocious and our late 80's C-36 about 40X worse than the C-310..... D'oh...
In a good DC panel design there is always a DC Main breaker. Some builders put this breaker right at the battery switch, to follow the standard, and keep the battery switch as close to the batteries as possible.
Here is but one example. The batteries are less than 30" away from the battery switch, & fused, and the DC Main breaker is also right at the battery switch to power the DC panel.
(http://www.pbase.com/mainecruising/image/165529881.jpg)
When considering feed wire to a DC panel always consider the maximum voltage drop.... I have measured far too many boats exceeding 6% or more voltage drop between battery voltage and navigation lights.
11.14.1.2.6 Voltage Drop - Conductors used for panelboard or switchboard main feeders, bilge blowers, electronic equipment, navigation lights, and other circuits where voltage drop must be kept to a minimum, shall be sized for a voltage drop not to exceed three percent. Conductors used for lighting, other than navigation lights, and other circuits where voltage drop is not critical, shall be sized for a voltage drop not to exceed 10 percent.
Quote from: mainesail on May 26, 2017, 04:21:19 AM
It is a 9" long wire because the battery switch is physically mounted in the DC panel board..
Rod,
Yep I knew that, but just so I don't mis-interpret, I'm not sure the reason why you are calling that out.
Can you clarify?
My point was merely that a sheath/conduit can't substitute for a fuse (in this particular situation.)
As far as having a main breaker, Ha Ha. :rolling Good Memorial Day humor!!
(http://bestanimations.com/Flags/USA/usa-american-flag-waving-animated-gif-34.gif)
Cheers,
Ken
We're lucky the old Seaward panels had a main AC breaker!
"sister" panel:
Quote from: mainesail on May 26, 2017, 04:21:19 AM
In a good DC panel design there is always a DC Main breaker. Some builders put this breaker right at the battery switch, to follow the standard, and keep the battery switch as close to the batteries as possible.
I'm curious, in the case where the battery switch is at the battery box and there is a suitable fuse near the battery switch protecting the wire to the Main DC panel, do you consider it poor practice to not have a readily accessible Main DC breaker somewhere (breaker rather than fuse)? I realize it's nice to be able to use a breaker to turn off the Main DC Panel, and one could argue that there is a safety benefit to being able to quickly restore power to the Main DC Panel after an overload, but are either of those sufficient to warrant a breaker over a fuse in order to be considered "good design"? I know it's a judgment call, but I would value your professional insight.
Quote from: J_Sail on May 26, 2017, 11:29:05 AM
Quote from: mainesail on May 26, 2017, 04:21:19 AM
In a good DC panel design there is always a DC Main breaker. Some builders put this breaker right at the battery switch, to follow the standard, and keep the battery switch as close to the batteries as possible.
I'm curious, in the case where the battery switch is at the battery box and there is a suitable fuse near the battery switch protecting the wire to the Main DC panel, do you consider it poor practice to not have a readily accessible Main DC breaker somewhere (breaker rather than fuse)? I realize it's nice to be able to use a breaker to turn off the Main DC Panel, and one could argue that there is a safety benefit to being able to quickly restore power to the Main DC Panel after an overload, but are either of those sufficient to warrant a breaker over a fuse in order to be considered "good design"? I know it's a judgment call, but I would value your professional insight.
J
Why not replace the fuse w/ a surface breaker, or thru-mount breaker next to the switch? (seems best of both world's option)
Or leave the fuse, and put a switch only at the panel to disconnect the feed?
ken
I call that out because Catalina likely interprets those 9" wires as "pigtails" which does not technically eliminate the need for a fuse or DC main breaker. If there was a DC panel main breaker, as many boats have, then one could use conduit or sheathing to "protect" the wire from a short (up to 40") but the breaker still needs to be there to prevent pulling more ampacity than the cable can pass.
Quote from: KWKloeber on May 26, 2017, 11:40:38 AM
Quote from: J_Sail on May 26, 2017, 11:29:05 AM
Quote from: mainesail on May 26, 2017, 04:21:19 AM
In a good DC panel design there is always a DC Main breaker. Some builders put this breaker right at the battery switch, to follow the standard, and keep the battery switch as close to the batteries as possible.
I'm curious, in the case where the battery switch is at the battery box and there is a suitable fuse near the battery switch protecting the wire to the Main DC panel, do you consider it poor practice to not have a readily accessible Main DC breaker somewhere (breaker rather than fuse)? I realize it's nice to be able to use a breaker to turn off the Main DC Panel, and one could argue that there is a safety benefit to being able to quickly restore power to the Main DC Panel after an overload, but are either of those sufficient to warrant a breaker over a fuse in order to be considered "good design"? I know it's a judgment call, but I would value your professional insight.
J
Why not replace the fuse w/ a surface breaker, or thru-mount breaker next to the switch? (seems best of both world's option)
Or leave the fuse, and put a switch only at the panel to disconnect the feed?
ken
Ken,
All of those are options, each with their own pros and cons. For example, the placement of a toggle circuit breaker in or at the battery box (which you present as best of both worlds) also opens the possibility of something inadvertently turning of the Main Panel, a risk not present with a fuse. These tradeoffs can be debated endlessly.
My posting, though, was specifically to solicit MaineSail's opinion as a leading professional in the field for his view of acceptable best practice.
Quote from: mainesail on May 26, 2017, 02:44:57 PM
I call that out because Catalina likely interprets those 9" wires as "pigtails" which does not technically eliminate the need for a fuse or DC main breaker. If there was a DC panel main breaker, as many boats have, then one could use conduit or sheathing to "protect" the wire from a short (up to 40") but the breaker still needs to be there to prevent pulling more ampacity than the cable can pass.
Thanks RC. I understand. I knew that the 9" (7") didn't app'y here. Great points about the V loss -- that's essentially what I did by doubling up on the feed wire to the switches ahead of the fuses.
As far as your point on Catalina, who ever knows what CTY/Seaward/Bristol/Universal thought about when building in the wiring deficiencies. The panel may be the least of them. My personal pet peeve is the dangerous engine harness, but sometimes it's like talking to a wall.
Cheers
Ken
Great debate but it does leave the unwashed with some puzzles to work through.
First, a correction and a bit more information. Since so much attention is being focused on the pigtail connecting the common terminal to the boat's DC circuits, I remeasured and it is less than 7" long. Not only is there no fuse there, but there is no master fuse between the the batteries under the starboard bunk and the battery switch several feet away above the nav table on the port side.
So what to do? I can easily put a 40-60amp inline fuse in the 10 gauge pigtail line. But is it worth the extra trouble and expense of putting in a main breaker between the batteries and the battery switch? I assume this would have to be breaker rather than an inline fuse. In fact I wasn't aware that you could get an inline fuse much over 60 amps. More important, wouldn't I have to install two master breakers to cover the house and start batteries since I would want to position a main breaker close to batteries that are far away from the battery switch? So, what to do?
All of those fuses should be there, but in my book the more important of the two is to have a fuse at the battery. Fortunately, if you have a little bit of headroom, BlueSea makes a Marine Rated battery Fuse and holder that mount directly onto the battery post. Take a look at:
https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A
Mainesail has discussed them on his site and on various forums.
http://www.pbase.com/mainecruising/battery_fusing
john,
If you look thru the 101 electrical topics there's probably a discussion of fusing (I'm sure Stu will point to it!!)But, understand that the length of that "jumper" (not pigtail) wire has no bearing on this particular situation.
1) There is no "exception" to having the feed to the 12v breakers or fuses (whichever you have) "fused." Up until the 10 awg wire leaves the C post, the switch is part of the starting circuit (exempt from fusing requirement -- but not a good idea.)
2) The 7" length pertains to a different situation (most commonly at the connection to a battery post.)
3) Also, that wire isn't a "pigtail" anyway. A pigtail has two common meanings:
a.) If you crimp, say, 4 wires together, and one of them
is a jumper (typically of the same gauge, e.g., to a switch, or a power source, etc..) that wire is a "pigtail." So a pigtail is a single wire "joined to" multiple wires.
light 1
--------\light 2
---------|------------- power source
light 3
--------/ ("pigtail")
b.) In ABYC it is also the short
(<7"), light-gauge wires on, for instance, a bilge pump (to which you connect your heavy the power and neutral wires to the pump.)
______
| Bilge |
---------------||
====== heavy-gauge feed from panel
| Pump |
---------------||
====== heavy-gauge neutral
| ____ | (<7" pigtails)
In other locations if you drop down to a lighter gauge there must generally be overcurrent protection for the lighter wire. Not so on that type "pigtail." The exception is there so dirtbag manufacturers can continue to supply light gauge wiring on the marine equipment they sell to us. (yeh, why wouldn't we want to butt crimp, say a 12 gauge or 10 gauge power feed to a 16 gauge pump wire???) They get away w/ it because the pigtails can handle the current, so cost prevails over common sense and avoiding voltage loss, not to mention that you need a special butt crimp to drop from 10 or 12 gauge to 16 gauge.)
Due to the potential for very high current, you
want a marine-rated fuse (instead of a breaker) [size=78%]on the main feed to the selector switch[/size].ken
Quote from: John Langford on May 27, 2017, 03:35:23 PM
First, a correction and a bit more information. Since so much attention is being focused on the pigtail connecting the common terminal to the boat's DC circuits, I remeasured and it is less than 7" long. Not only is there no fuse there, but there is no master fuse between the the batteries under the starboard bunk and the battery switch several feet away above the nav table on the port side.
So what to do? I can easily put a 40-60amp inline fuse in the 10 gauge pigtail line. But is it worth the extra trouble and expense of putting in a main breaker between the batteries and the battery switch? I assume this would have to be breaker rather than an inline fuse. In fact I wasn't aware that you could get an inline fuse much over 60 amps. More important, wouldn't I have to install two master breakers to cover the house and start batteries since I would want to position a main breaker close to batteries that are far away from the battery switch? So, what to do?
John
Your hull number is not that far from mine. Near the floor under the nav table I have a push/pull breaker between the battery and battery 1-2-all switch. Pull that switch out and power to panel is off. I would think yours is wired that way too.
Nope. The push/pull switch under my nav table controls the power to the windlass. It is rated at 135 amps. When it is on, a red light on the electrical panel comes on. There is no draw unless you engage the windlass with the foot switch in the anchor locker.
John,
Ours was 1602 (I know its later tan your) and like Roc's we also had a breaker under nav station just like below. So in your situation you only have one breaker? Maybe you can add a second, if there is room?
Yes, mine is just like Fred's picture.
Thanks for all the help and advice. I just installed a 150 amp Blue Sea block fuse at the battery bank end of the positive cable from the house bank (4 Trojan T105s) to the battery switch and DC electrical panel and a 30 amp inline fuse in the #10 gauge wire from the battery switch common terminal to the various DC panel circuits. I use the start battery so rarely (like never) that I have left the 0/1 cable from its positive terminal unprotected.
John
When you say "in line" fuse, what's the configuration? Is it a crimp on blade type fuse holder (ATC) or a barrel fuse? Do you want Ensure that the connections are good because any voltage loss there just travels down the line.
If it's a butt crimp-on fuse holder, make sure the fuse wire size is as large as the jumper.
Since the jumper is # 10 fusing should more likely be the wire capacity which is 60 amp in this application. It would really be worthwhile upping that wire size, # 8 would be good to cut voltage lost considerably. In fact if you'd like to do that, I'd be happy to mail you a jumper made up n/c.
Ken
Quote from: John Langford on May 30, 2017, 10:12:40 PM
Thanks for all the help and advice. I just installed a 150 amp Blue Sea block fuse at the battery bank end of the positive cable from the house bank (4 Trojan T105s) to the battery switch and DC electrical panel and a 30 amp inline fuse in the #10 gauge wire from the battery switch common terminal to the various DC panel circuits. I use the start battery so rarely (like never) that I have left the 0/1 cable from its positive terminal unprotected.
A 150A fuse for starting may
eventually nuisance trip on you..... You just hope this does not occur when you really need the engine... For any bank that can be used to start engines I usually recommend using a 250A to 300A main battery fuse. These fuses also need to meet the AIC requirements of the bank so Class T, ANL or MRBF are the three go-to fuse types for bank protection..
Course Catalina used 4GA wire on many boats, max ampacity of about 160A with 105C wire with no derating factored in, and no fuse at all. A fuse is always going safer than no fuse at all, unless it nuisance trips.
Thanks very much to both of you for the follow up.
The 30 amp blade fuse holder came with short 10 gauge tails so I crimped the appropriate fittings on either end and used it to replace the existing unprotected 10 gauge connector from the common terminal to the panel circuits. My calculations suggest that I would have to have every pump, the frig, all the electronics and every light running at the same time to get anywhere near 30 amps. My crimps are done with a professional crimped and my system has run successfully for 18 years with a 10 gauge wire so I should be ok. Thanks very much for the advice and the offer Ken.
The Blue Sea terminal block fuse is a MBRF, the wire gauge is 1/0 and the run length one way must be all of 20 feet from the battery bank under the starboard settee to the battery switch on the electrical panel and then to the engine. I will buy a more robust cube fuse on your advice, MS. Apologies, but I don't know your name.
I have a boxfull of 10 gauge ATO/ATC capped (weathertight) fuse holders if anyone else wants to make their distribution panel safer and add a fuse to their (10 gauge) panel feed, or a fuse to their cockpit panel feed wire (my "Universsl" pet peeve.) Looking for a new home, here for the asking.
If you want it with an M8 starter lug to fit the starter solenoid post it would be slightly more than "free".
kk
MaineSail's name is Rod, but mostly we just call him MaineSail; he doesn't seem to have taken offense yet.
Double-check your calcs and keep a spare fuse or two onboard, just in case, but you may well be just fine. If at some point you ever decide to fuse the #10 a bit higher, BlueSea does make an inline fuse holder that can take Maxi fuses as large as 60A (although the holder is rated at 48A continuous, so I would not fuse it above 50A). It has #6 pigtails, but could be readily spliced to your #10.
https://www.bluesea.com/products/5068/MAXI_In-Line_Fuse_Holder
I would encourage you to fuse your reserve battery too. It doesn't matter if it's almost never used, the concern is something somehow causing a short in its cable. That could occur from something hitting, cutting, or chafing the insulation somewhere or from a careless moment during servicing, with potentially catastrophic results. Unless you are severely limited on vertical height, it's trivial to add a BlueSea MRBF/holder right to the battery terminal.
https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A
If you have not yet read MaineSail's article, it (and all his others) are a valuable resource.
http://www.pbase.com/mainecruising/battery_fusing
Enjoy,
Jeremy
Jeremy, Maxis are also available in 8 gauge which makes butting a bit easier,
I'd have to hunt back and locate my source for them if anyone is interested.
kk
Jeremy's prudent advice re fuse protection for the cable from the start battery to the battery switch sent me back to take another hard look at the wiring of my electrical panel. Almost everything on the panel is powered from the common terminal on the battery switch and thus protected by the 30 amp in line fuse I have just put into the 10 gauge connection between the common terminal and the panel circuits. The significant exception is the power for the electric bilge pump that comes directly from the house battery terminal of the battery switch. Should that connection be independently protected by its own inline fuse or, since the bilge pump is the only potential power draw on that connection, is the protection provide by the bilge pump breaker on the panel enough?
PS by way of explanation, the bilge pump is powered directly from the house battery terminal on the battery switch because the automatic bilge pump must have access to power even when the battery switch is off and I am not around to turn it on.
The short answer is a definite YES.
The primary purpose of fusing is to prevent the wiring from becoming a fire hazard in the event of an overload. The cause of such overload can be a failure in a device or a short circuit in the wiring (due to a breach in the insulation). Thus the wire to the bilge pump needs protection even though the only intended load is the pump. What if something like either a loose anchor or a sharp edge of a screw shorts the bilge pump supply wire to ground? In that scenario, the small normal draw of the bilge pump is no longer a factor, and the unprotected wire rapidly overheats and potentially starts a fire.
Thus the advice to size fuses/breakers (aka over-current protection or OCP) to protect the wire, not the load. The largest allowed amp value is a function of the gauge of the wire, the temperature rating of the wire's insulation, how many wires are bundled together, and whether the pathway includes an engine room or not. It is not a function of what the load normally draws. Those guidelines also allow one to slightly oversize the fuse in certain circumstances.
HOWEVER, there are limited cases where one MAY choose to undersize the OCP. One of those is for motor loads, where it might be nice to have a breaker that trips when the motor becomes temporarily overloaded due to something jamming it. In that case, there is a point of view that having a breaker that trips and can be conveniently/quickly reset may be better than risking the motor overheating and burning out. Some bilge pump manufacturers provide a spec for such a breaker. In that case you may want to use a breaker that is smaller than the rating of the wire. If it's a fuse rather than a breaker, then I would probably not undersize it, as a blown fuse is almost as bad as a blown motor if you can't quickly find and replace the fuse.