PDA

View Full Version : Splitting AC Circuit?



JLR
07-25-2011, 07:26 AM
I am at a marina where the dock power is very light. Even using my buc boosts, I am popping the breaker on the dock using only one 50 amp line. I am about to run another 50 amp line as well but in looking over the Hatteras manual, I noticed that all air conditioning units are on the same ship's service (in my case, ship's service 1). While I can run everything else off of the other 50 amp line (ship's service 2 and 3), I was curiuous about why Hatteras would combine all a/c units on only one ship's service. Also, off the top of anyone's head, any idea of the amperage draw of running 4 a/c units at the same time. That's what I'd like to carry on the one 50 amp line that will be devoted to ship's service 1 but I am not sure the dock will carry it without popping the dock breaker. Thanks for the help.

TopHattandTails
07-25-2011, 08:02 AM
You should be under 50 amps. I might top out around 40 amps with all 5 ac's. But beware - the buc boost will not give you 50 amps. You will have to load balance.

JLR
07-25-2011, 08:39 AM
Not sure what you mean by load balance here. I know the Buc Boosts raise the voltage a bit but that is all.

MikeP
07-25-2011, 09:01 AM
The 4 units on our '80 53MY will run on the single 50A line but it's marginal and if an item like a hair dryer is on the same circuit, that will exceed the line capacity.

But it will depend on the condition of the ac units themselves - we were having a problem where the salon ac would draw around 70A for startup which, depending on other loads, would pop the breaker. Turned out to be an arcing connection/corroded wire at the compressor. After fixing that, the startup load dropped to less than 30A

REBrueckner
07-25-2011, 09:18 AM
"Also, off the top of anyone's head, any idea of the amperage draw of running 4 a/c units at the same time."

A 16,000 BTU unit with an EER of 9 will draw 16,000/9 or about 1,778 Watts...at 120 volts thats
1778/120 almost 15 amps....(or about half that at 220 volts)

But I have never been able to determine the EER of marine wter cooled units....which likely varies by brand name and vintage anyway.....you can easily modily the above estimate by multiplying 15amps by my estimated EER or 9, then divide by whatever EER might be more accurate.


So likely a 50 amp circuit breaker would just barely handle 4 units running.... on a good day....I don't know about start up current surges.

"I was curiuous about why Hatteras would combine all a/c units on only one ship's service."

because they did not think enough about it....Hatteras was very good, not perfect.

JLR
07-25-2011, 09:31 AM
Thanks. With the kids on board, at least three units will be going at night and I'd like to keep the salon unit on as well so I do not loose the ability to cool the salon during the day. Even being able to run 3 at one time would carry us for the week or so. I can split off everything other than the AC's onto a separate line so I guess I might just experiment to see how much load the dock will permit. It is odd that the breaker that pops is not the one on the boat, nor the one on the pedestal but rather the one down the dock on the main panel. Funny for $5.50 a foot per day plus a $25 or so daily charge per 50 amp line (plus a resort fee), one would think this would not be a problem.

captddis
07-25-2011, 10:07 AM
Are all the AC's on the same breaker panel? All of the MY'S like yours I have been on the Ac's are divided into a couple different panels and can be seperated by using the source breakers at the bottom of the main panel.

spcoolin
07-25-2011, 10:08 AM
It's not uncommon for marina breakers to get weak & not carry rated load...

See if you can get the dockmaster to switch out that tripping breaker with a fresh one.

I can total up what you should be drawing, but will need to know what size & voltage your units are.
If the units are due for a flush they will draw more than rated amps...Refrigerant charge can affect this too...

Steve~

JLR
07-25-2011, 10:25 AM
Steve - thanks. The units are OEM Hatteras installs on a 1981 56 MY.

captddis - the AC units are all on Ship's service 1 which cannot be split.

spcoolin
07-25-2011, 10:33 AM
Don't think I have been aboard a 56 MY...So I still need sizes & voltages...

Steve~

saltshaker
07-25-2011, 10:45 AM
Are all the AC's on the same breaker panel? All of the MY'S like yours I have been on the Ac's are divided into a couple different panels and can be seperated by using the source breakers at the bottom of the main panel.

That's the same as what I've seen on most Hatts. My 65EB has the AC's split between 3 panels and you choose what source energizes each panel. I have a 30K unit for the salon, 3 10K units for the staterooms and a 24K unit for the bridge. All will run on one 50A cord but that doesn't leave much reserve. With the bridge unit off we can run all the others plus the water heater with no problem. Remember if you are boosting voltage then there will be a higher amperage draw at the pedestal than what you see on the boat.

JLR
07-25-2011, 11:09 AM
Steve - sorry - boat is in Montauk and I am at my office elsewhere. I do not have that information as we speak. Voltages are all 240 volts- I believe. Never even tried to run the boat on a 125v 30 amp line. As for splitting off the AC's, here is the best picture I can paint from memory. I have 3 ship's service panels. Each one is labelled 1, 2 or 3. Correcting my prior post, all of the AC units are on Ship's service panel 2. On my main board, I have three sets of breakers--each one can be set for Ship's service 1, 2 or 3. So, assuming I isolate Ship's Service 2, on a breaker devoted to that Ship's service only, I can then set the other breakers and the other Ship's services (1 and 3) to the other set of breakers. Unfortunately, all of the AC units are on the same Ship's service so there is no way to split them off from each other or split them up. However, after owning the boat for the past 13 years, if I am wrong and there is a way to do it, I would be happy to learn. My guess is that only Roger Wetherington knows for sure. Also, as to silly wiring choices--here is another one. Whomever chose to install dual Glendinnings on my boat (port and starboard) wired it in such a way so that one cannot run a line from each side (port and starboard). They both are on the same circuit. So, to run 2 50 amp lines using one of the Glendinning lines requires a separate (non Glendinning) 50 amp line. What that means is that knowing this (now), I need to always carry a spare 50 amp line even though I have two 50 amp Glendinning lines installed. Not a great choice, IMHO.

saltshaker
07-25-2011, 01:07 PM
If your boat is similar to mine, you have 2 separate 50/250 and one 50/125 connection on each side of the boat. Sounds like they wired both Cable Masters to ship's service 1. I would verify that and swap the wiring for ship's service 1 and ship's service 2 on one side of the boat. Don't forget to relabel the inlets.

JLR
07-25-2011, 01:33 PM
Good suggestion.

GJH
07-25-2011, 01:55 PM
I have the same boat as JLR. If the A/C is going to be used heavily (winter or summer) I run it on its own 50 amp line ("Source 2) and the other ship's services off another (Source 1). We can cook and run the clothes dryer and dish washer this way. Trying to run it all off one 50 Amp source doesn't work. The 20kw generator, equipped with an 80 amp breaker, also can run everything.

JLR
07-25-2011, 02:12 PM
George - thanks for chiming in. That's exactly what I intend to do when I return to the boat. I need to bring along another 50 amp line to do so but the setup should work. I too had been running my 20KW genset to avoid the overload problem. That should not be necessary once I have another 50 amp line hooked up. Do you happen to know offhand how manny of the AC units you have can be run off of that one 50 amp line.?

MikeP
07-25-2011, 07:50 PM
"Funny for $5.50 a foot per day plus a $25 or so daily charge per 50 amp line (plus a resort fee), one would think this would not be a problem."

You never know about marina power. We stayed at a nice marina for two nights last year and their 50A 240V was actually around 205V and wouldn't run any of the 240 stuff. We had to run the genny to use ac.

Geoff58yf
07-25-2011, 08:07 PM
[QUOTE=spcoolin;193965]It's not uncommon for marina breakers to get weak & not carry rated load...

See if you can get the dockmaster to switch out that tripping breaker with a fresh one. "

We've encountered similar problems on both coasts. We were amazed at how many marinas have 'tired' 50amp breakers. In nearly every instance, when we could get the harbormaster to pop in a new breaker, the problem was solved.. Beats dropping another $300+ for a 50amp cord.

flydixie1415
07-25-2011, 10:10 PM
My quess the reason that the ac's are all on one breaker is because of the ac pump. I assume you only have one. That's all we have on our 56. My ac units run off of the center breaker on the panel. Check your big fuses also. I had several blow the breakers last week when it was 100 degrees last week. You should be able to see on your meters how many amps your ac's are pulling. I can run all 5 of mine. Best if luck

GJH
07-25-2011, 10:31 PM
I can run all five of mine as well, but seldom do. 4 is not uncommon. We also have a 115 volt Mermaid in panel 3 for the aft deck that comes into play every so often. We are out on the hook( or a mooring) a lot, and the 20kw Onan with 80 amp breaker has never skipped a beat with it's 80 amp (19.2 kw) breaker. But I have tripped shore power on one 50 amp line on several occasions with strong 240+ power from the pedestal.

REBrueckner
07-26-2011, 07:50 AM
It's been interesting to read about the heavy electrical draw in Marinas being such a common problem. Fortunately my old 48 YF had only two 16K BTU units which I rarely used, so I never gave shorepower power shortages much thought. After I replaced the original four burner 220 volt electric stove with a four burner home cooktop, my 12KW ONAN was ridiculously oversized.

In Nova Scotia at commercial docks, I was able to get by with a single 15 amp supply to keep my batteries charged...there was no charge!! (In fact a recreational boat from the US with a Yorkie aboard was a novelty and I had a lot of vistors.) With diesel heat and propane cooking, my electric demand could be easily managed within 15 amps, 120 volt. All I had to do was shut off some miscellaneous stuff while I heated domestic water via an 1800 watt electric element.

I have noticed for years that the megayachts in some marinas are not only plugged in with multiple, really thick shorepower cords, they also run their generators full time. In Nantucket boat basin, for example, where the "big boys" tie up via bow anchors, stern to the dock, 150 ft and bigger, I was always turned off by the drawn curtains, neighbors a fender thickness away, and generators (although very quiet) going 24 x 7.... And was glad I never had to pay for one of those megayacht cords. Not my idea of how to enjoy the tranquilty and views at Nantucket Harbor, but maybe they have to show off to each other??.

JLR
07-26-2011, 08:20 AM
All good suggestions but baby steps first. Right now, I am hounding the Marina to at least fix the second 50 amp outlet on the post so that I can even use two 50 amp lines. Once that is done, I can then move on to the breaker on the main down the dock. Several years ago, I had an electrical contractor install two boost switches on my transformers (taken from the taps--whatever they are) so that I would be in a position to even get by at marinas like this. Like Mike said, the actual voltage here is barely 200 (probably meant to be 208) but with the boost switches on, I can boost it up to 240 or so, dropping to no lower than 230 under load. Has anyone decided to use one 100 amp line and some sort of combiner with two short 50 amp feeds? It seems less cumbersome.

GJH
07-26-2011, 06:49 PM
Less cumbersome, but a custom piece that will cost you about $2500+ from some place like Ward's Marine Electric. Get 2 quality 240/50's (via your Glendinnings if possible) and be done with it. Works for me, and I hate this kind of work!

saltshaker
07-26-2011, 07:15 PM
All good suggestions but baby steps first. Right now, I am hounding the Marina to at least fix the second 50 amp outlet on the post so that I can even use two 50 amp lines. Once that is done, I can then move on to the breaker on the main down the dock. Several years ago, I had an electrical contractor install two boost switches on my transformers (taken from the taps--whatever they are) so that I would be in a position to even get by at marinas like this. Like Mike said, the actual voltage here is barely 200 (probably meant to be 208) but with the boost switches on, I can boost it up to 240 or so, dropping to no lower than 230 under load. Has anyone decided to use one 100 amp line and some sort of combiner with two short 50 amp feeds? It seems less cumbersome.

A 50' 100A 125/250 cord will cost around $2800 and weighs 75lbs. Best to go for the 75' cord but that's going to run you another $800 and it weighs 120lbs. The boat side receptacle is another $700. Then you'll need a 100A to two 50A Y cord that's another $4500. through in a few hours labor to change things over and for 9K-10K you're done. If you want 100A service at the slip then you'll be in a big slip with a big premium, if you can even get one. If you go that route then you better add some extra labor to pull out the Cable Masters or wire in another shore connection and change all your selector switches to accommodate a third source.

Swap one of the Cable masters to feed shore power 2 and you're good to go. If it takes an hour to do the job then someone probably took a break.

JLR
07-27-2011, 08:32 AM
It sounds like switching the cablemaster is clearly the way to go. Thanks for the help.

TopHattandTails
07-27-2011, 11:23 AM
Not sure what you mean by load balance here. I know the Buc Boosts raise the voltage a bit but that is all.

Boost transformers do not solve all your problems. If all your air is on one panel,as many boats are, and you cannot split them up between shore cords, then you only have 42 amps available after boosting so you won't be able to run all your air units. simple math kicks in here....

- 240 V x 50 A =12,000 watts of power. This is what you need on each cord in a perfect world ( not a marina )

- 208 V x 50 A = 10,400 watts. Cruisair can run on this and survive. You can still draw 50 amps.

- 208 V x 50 A = 10,400 W a Buck / boost ( 10,400 div by 240 ) = 43.3 A @ 240 V. Figure a little less for transformer loss so

- 208 V @ 50 A gives you 42 A @ 240 V boosted. If all your air is on one panel you will have to load manage (e.g. not run one of the A/C's).

Once your boosted (or unboosted 208v), your lights and plugs will only get half of the voltage - so in a 240v scenario, you'll get 120v; or in a 208 v scenario, you'll only be getting 104v - that is where you need to check your refrigerators, dishwashers, other appliances for tolerances. In my case its all of the florescent lights (they take a bit more to get the mercury charged and light up than what the 104 can yield). Check the manufacturer specs to see what voltage the appliance can tolerate. They might indicate 100v - 130volts or something along those lines.

JLR
07-27-2011, 11:43 AM
Thanks for all of the good information. Now --a bit more--if possible. Although I will not be doing this myself (so as not to make any of my friends out there nervous), can you give me a start on how I would go about switching the feed on one of the 50 amp Glendinning lines to the other Ship's service so I can run both lines at the same time. As previously stated, they are both on the same service so I cannot do that now. In other words--remove from where and reconnect where?

saltshaker
07-27-2011, 12:18 PM
Thanks for all of the good information. Now --a bit more--if possible. Although I will not be doing this myself (so as not to make any of my friends out there nervous), can you give me a start on how I would go about switching the feed on one of the 50 amp Glendinning lines to the other Ship's service so I can run both lines at the same time. As previously stated, they are both on the same service so I cannot do that now. In other words--remove from where and reconnect where?

How do you power the boat at your home slip? do you always use 2 lines or do you just run 1 50A? I don't know how yours is wired so this would only be a thought of where to look. I'm basing this on how mine is set up from an operating stand point. Are you positive the Cable Masters are both on shore power 1? This makes no sense to me since you can select what feeds each panel from the selector switches. If they are, you should be able to swap the Cable Master connection with shore power 2 right where the Cable Master is tied in. They probably connected to the original shore power 1 receptacle wires. You might also be able to switch the shore power 1 and shore power 2 feeds from 1 side where it feeds the panel. You need to verify how all this is wired first. The port and starboard receptacle may be wired together. You do not want to connect shore power 1 with shore power 2. I would start with locating the connection of the cable from one of the Cable Masters. That would seem to be the obvious spot to make the switch. If you're not comfortable with this type of work, pull out the electrical drawings and do some investigating first. Then get a good marine electrician to do the switch for you.

JLR
07-27-2011, 12:50 PM
Ok--here is what I know. I only use one 50 amp line at my home slip. I do know that both cablemasters are on the same source (in my case--source 2). I seem to recall that the Hatteras OEM hull outlets (giving you an option of source 1 or source 2) on at least the starboard side of my boat, will now only permit me to use source 1. Thus, I am virtually certain that the cablemasters are both hooked up to source 2 using the wiring that was originally intended to be used by Hatteras at the OEM plug labelled source 2. I am not sure whether source 2 has been stolen from both sides (port and starboard) but my guess is that they have been with source 2 being stolen for the cablemaster on my port side and source 2 also being stolen for the cablemaster on on my starboard side. With all of this said, I have been able to locate a new 50' 50 amp line for about $450 and it might be an easier solution just to carry that as a spare.

GJH
07-27-2011, 01:43 PM
Unfortunately (for me and for you) I don't have Cablemasters so can't help on the hook up. I'd try giving Glendinning a call, they are usually helpful and seem familiar with Hatteras boats.

Where are your CMs mounted, internally (storage and mechanism) and externally (where you pull the cord out)? This is an item fairly high on Ann's Boat List, especially now that we reupholstered everything in the salon....

JLR
07-27-2011, 01:54 PM
George - the internals for the cablemaster are in each engine room. Starboard engine room just behind the hot water heater and on the port side all the way in the forward outboard corner. On the outside, they exit the hull just next to the Hatteras quick disconnect water fittings on each side. At 5' 10", I just barely can reach the cover for the CM's when leaning over the rail from the deck. No problem dockside if on a floating or fixed dock. They sure are nice to have when they are wired correctly. I'll give Glendinning a call and see if they can help. Thanks.

saltshaker
07-27-2011, 01:58 PM
Ok--here is what I know. I only use one 50 amp line at my home slip. I do know that both cablemasters are on the same source (in my case--source 2). I seem to recall that the Hatteras OEM hull outlets (giving you an option of source 1 or source 2) on at least the starboard side of my boat, will now only permit me to use source 1. Thus, I am virtually certain that the cablemasters are both hooked up to source 2 using the wiring that was originally intended to be used by Hatteras at the OEM plug labelled source 2. I am not sure whether source 2 has been stolen from both sides (port and starboard) but my guess is that they have been with source 2 being stolen for the cablemaster on my port side and source 2 also being stolen for the cablemaster on on my starboard side. With all of this said, I have been able to locate a new 50' 50 amp line for about $450 and it might be an easier solution just to carry that as a spare.

I would think you should be able to sort out the Cable Master for less and it would be much nicer than lugging around another cord. Are you confusing source 1 and source 2 with ships service 1, 2 and 3? one refers to the power source the other to the AC distribution panels. $450 is a good price for the cord. Is it 50' and 125/250? What brand is it?

JLR
07-27-2011, 02:19 PM
Jack - source two (rather than ship's service 1, 2 or 3) is the source that both CM's use (unfortunately). The cord is a Charles cord and is indeed a 50' 125/240 albeit in white. No link-- but it is carried online by Imarine.

saltshaker
07-27-2011, 02:38 PM
Jack - source two (rather than ship's service 1, 2 or 3) is the source that both CM's use (unfortunately). The cord is a Charles cord and is indeed a 50' 125/240 albeit in white. No link-- but it is carried online by Imarine.

I guess who ever wired it thought they neede source 2 to power the AC units. Is this the cord and supplier? They have it listed in yellow.
http://www.imarineusa.com/charles50amp125250volt50footcablecordset.aspx
That's a good price. The Charles cord sets are also sold at Defender, they may have it in yellow. I bought one of the Furrion 50' 50A 125/250 cords for $479. I like the way the ends are made. I would definitely buy another.

JLR
07-27-2011, 02:57 PM
Jack - here is the one in white (but I prefer the yellow one in the link you sent on):
http://www.imarineusa.com/charles50amp125250volt50footcablecordsetwhite.aspx . I guess I will just buy one. I called up Sailorman to see what they had and somehow the idea of buying a used one and the general hassle of dealing with them turned me off.

TopHattandTails
07-27-2011, 05:06 PM
Jack,
I'd be happy to trade you my yellow Marinco 50'-50A-125/240 (detached) yellow cords for your cable masters with white cords! One cord is 1 season old, the other is a bit older. :)

spcoolin
07-27-2011, 05:54 PM
Gee...How bout posting a pic of your panel...

Steve~