When to use Parallel on the panel

[golfwins]

Will someone please confirm this for me? I have a 2003 Maxum 2700 SE. On the electrical panel, there is a switch that is labeled Parallel. Is that only use in the event that there is only one shore power available to my dual shore power boat? Here is s snippet from a manual I found. I currently have it on with two shore powers connected. I hope it's not doing any harm.

When only one dockside outlet is available, you can use the parallel switch to provide power to both lines.
1. Connect to shore power as described in the Connecting to Shore Power section above.
2. Switch the parallel switch (transfers power from line 1 to line 2) On instead of the SHORE POWER 2 master breaker.
3. Turn On the individual component breakers as required

[mmwjr]

Yes it shares line 1 with line 2. Line 2 is typically only used for air conditioning.

[golfwins]

Thanks! That second piece of info is great to know too. I appreciate it!

[dbriceno]

It's kind of silly that many smaller boats have twin 30 amp lines and larger boats have a single 50 amp line. Why would the small boat ever need a combined 60 amps? Typically only one A/C, small water heater and fridge. My old 4600 had 2 A/Cs, big fridge, ice maker, big water heater and never an issue with a single 50 even with my wife using a blow dryer.

Is there a good reason? Using the single 30 and the parallel is so much easier. In addition, smaller boats even have smaller generators (usually 5-7.5 kw) that seem to handle the load just fine

[mmwjr]

Originally Posted by dbriceno

It's kind of silly that many smaller boats have twin 30 amp lines and larger boats have a single 50 amp line. Why would the small boat ever need a combined 60 amps? Typically only one A/C, small water heater and fridge. My old 4600 had 2 A/Cs, big fridge, ice maker, big water heater and never an issue with a single 50 even with my wife using a blow dryer.

Is there a good reason? Using the single 30 and the parallel is so much easier. In addition, smaller boats even have smaller generators (usually 5-7.5 kw) that seem to handle the load just fine

Sounds like someone has power envy

It’s most likely because of shore power options are 30 or 50 amp and even a small boat can load a 30 amp with range, microwave, water heater, tv, other brought aboard appliances. So if it has AC and the start up time of it overlaps the other items the resultant surge could trip a 30 amp breaker.

[golfwins]

After checking my boat yesterday, I noticed I can't even turn on Parallel if shore power 2 is on so it all makes sense now. I appreciate the feedback.

[shrew]

It's for the Generator ONLY. Both panels combined will exceed the 30 amps shore circuit. So the boats split the panel. The manufacturer provided 2 x 30 rather 1 x 50 because there are very few stanchions for 28-40 foot boats with 50 amp service.

The parallel switch is to allow the generator to power both AC circuits on the panel.

If you plug in a single 30 amp shore cord and use the parallel switch you can have power to both sides, but will need to manually balance loads.

I had a neighbor do this because he was too cheap to buy a second shore power cord, The boat breaker tripped before the power stanchion breaker, but not before frying his cord.

[forbes210]

I got rid of second cord years ago on my 2500 scr from 2002. Never had a problem and I tripped breaker on dock post only once through out many years. It rarely happens that I'll be using many devices at the same time and managing single cord is so much easier.

[dbriceno]

mmwjr - Good point, forgot about the microwave and the stove
Shrew - Yes, not worth frying a cord. If only using a single cord you need to be really managing your usage. Often cords get fried at the connectors with large loads.

Thanks for the replies.

[shrew]

Originally Posted by dbriceno

Often cords get fried at the connectors with large loads.

Yep, that is exactly where my neighbor's fried. Again, possible, but not a good idea.

Honestly, if you're already dealing with a single cord, dealing with two is no more cumbersome. I handle them in a set. I coil and uncoil them together. I've been thinking about using velcro cable ties, to make them more manageable, but it hasn't really been an issue.

[Dhalter]

Just so we are clear - you are talking about the parallel switch on the main panel in the cabin?
My 1998 3700SCR has been converted to single 50, despite the fact that my panel has two lines. I have an adapter cord for 30A, and am very judicious about what I run off the dock...

BTW, there is a PARALLEL switch on the cockpit panel - that has nothing to do with 110V service - that is to parallel all of the batteries in an emergency to start the engines in case one of them batteries is run down. That switch should not be applied while the engines are running, or you will fry the alternators.

[shrew]

Originally Posted by Dhalter

Just so we are clear - you are talking about the parallel switch on the main panel in the cabin?

Originally Posted by golfwins

Will someone please confirm this for me? I have a 2003 Maxum 2700 SE. On the electrical panel, there is a switch that is labeled Parallel.

That is what I assume.

[golfwins]

Yes, I'm all set now. Use parallel while on the generator if I want air conditioning.

The panel wont let me turn parallel on when both shore power cables are connected and switched on so its dummy proof there.

I appreciate all the help.

Sent from my SM-G965U using Tapatalk

[Dewey]

Can I use an adapter to split the power to line 1 and line 2? It's a 30 amp adapter. I do not have access to 2 power outlets where I dock my boat but would like to run the AC when plugged into the shore power. When I plug into just line 1, the AC will not run. Please help!!!

[mmwjr]

Originally Posted by Dewey

Can I use an adapter to split the power to line 1 and line 2? It's a 30 amp adapter. I do not have access to 2 power outlets where I dock my boat but would like to run the AC when plugged into the shore power. When I plug into just line 1, the AC will not run. Please help!!!

While this can be done you’ll have to be mind full of how much load you have turned on so that the total of line 1 & 2 don’t exceed 30 amps including inrush current when the AC or refrigerator compressors turn on.

[Dewey]

The power supply I plug into is only 30 amps so it won’t exceed more than that. Can I just plug into line 2 only and run the AC only? When my shore power is plugged into line 1 and running parrallel, when I kick the AC on, the breaker pops.

[mmwjr]

Yes you can only connect to line 2 and turn it’s breaker on to run the AC.

[Dewey]

Originally Posted by mmwjr

Yes you can only connect to line 2 and turn it’s breaker on to run the AC.

Thank you for your help!! This will help me figure out of my AC is bad or if I don't have enough power to run it by using Line 1 only. I have a feeling something is wrong with the AC system because when I had the shore power connected with Line 1, no other breakers on, it would kick the breaker when the AC tried to start. Bad pump or locked up compressor may be what I am facing. Any info on this would help too!!

[mmwjr]

Disconnect the AC unit to see it the water pump is locked and tripping the breaker. If water pump runs connect AC with compressor disconnected to see what happens.

[Dewey]

Originally Posted by mmwjr

Disconnect the AC unit to see it the water pump is locked and tripping the breaker. If water pump runs connect AC with compressor disconnected to see what happens.

Thank you!!! This process will help me eliminate each part. The system doesn't seem real complicated. I'll see what happens this weekend when I get a chance to work on it. Thank you so much for the help!!!