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Old 04-08-2012, 09:17   #1
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How many 30 Amp inlets?

I have an older Moody 42 that has had all the 220 VAC removed and replaced with one 30 amp inlet going into a Newmar panel. Currently living aboard.
I am running a 16,000 BTU AC, and powering a rectifier/power supply to power all the 24 volt systems which consist of a few lights, fridge, water pump, etc.
The 120 loads are the AC, water heater microwave and a couple of lights. I'm a bit concerned that I'm over doing the amp load with just one inlet. Your thoughts???
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Old 04-08-2012, 09:31   #2
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Re: How many 30 Amp inlets?

your bumping the upper limit. How does the voltage drop when everything runs compared to not running?
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Old 04-08-2012, 09:42   #3
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Re: How many 30 Amp inlets?

With a 16k AC and a waterheater you'll end up with a burnt plug before too long, If your dock will support it, upgrade to 50 amp service and you'll have no worries.
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Old 04-08-2012, 09:49   #4
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Re: How many 30 Amp inlets?

Not sure how to measure the voltage drop. I was thinking of adding another 30 amp inlet and running the AC off that. Had not considered 50 amp. How would I convert to 50 amp. Cost is a consideration.
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Old 04-08-2012, 09:50   #5
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Re: How many 30 Amp inlets?

Take voltmeter measure volts on power line with
nothing on
then something on
then another thing on etc...
until you have everything on and see what it reads.
Bad to drop voltage to low 100's

How about when the AC is on, dont run the water heater etc...
You can if you notice voltage dropping or power inlet gets hot under the load run things one at a time.

Cheaper to just add another 30 amp input line. The hots are on different phases, then you will have 60 amps not 50 nor 30 .
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Old 04-08-2012, 09:54   #6
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Re: How many 30 Amp inlets?

The AC alone might be pulling 20 amps. But if the panel is wired correctly and there's a maximum 30A breaker on your AC, in theory it trips out before the power inlet catches fire. If the wiring was done incorrectly and over-fused...cold be a big problem.

Upgrading to 50A wiring would be the easy way to go, but you might also want to start looking at rating plates to see just how much current each piece of equipment pulls, and whether that can be managed on 30A or not. (I suspect not, if the AC and any other substantial load are on at the same time.)

The drawback to "twin 30's" is that it is possible, from wiring faults or bad marina wiring, etc. to get the two out of phase and create more mysteries, that just can't happen if you're using one 50A supply. Either way will work--but with twin 30's you need to anticipate keeping things separate.
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Old 04-08-2012, 09:55   #7
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Re: How many 30 Amp inlets?

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Originally Posted by sdowney717 View Post
How about when the AC is on, dont run the water heater etc...
Second that suggestion. Shouldn't be too difficult to manage the load by not running AC and hot water at the same time.
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Old 04-08-2012, 09:58   #8
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Re: How many 30 Amp inlets?

upgrading to 50A would be close to $1k for the inlet, the cord, 8awg wire to the panel and a 50A breaker.

adding a 30A circuit dedicated to the AC would run less than half.
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Old 04-08-2012, 10:00   #9
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Re: How many 30 Amp inlets?

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Second that suggestion. Shouldn't be too difficult to manage the load by not running AC and hot water at the same time.

In Kemah TX the AC is always on, the 16K btu AC unit by itself is enough to melt shorpower cord ends when the contacts get a little corrosion on them.
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Old 04-08-2012, 10:06   #10
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Re: How many 30 Amp inlets?

I run two 30 A inlets that I can combine at my AC panel as required. I do agree that the A/C and the heater are pushing things. For reference, my 12,000 BTU A/C "kicks" at 17 amps and then falls back to 6 to 10 amps. If the fridge and the A/C started at the same time, there might be a funny smell unrelated to cooling things.

So perhaps the "A/C plus a couple of lights" circuit on a dedicated 30 A inlet is the answer, depending on whether where you dock will allow a second 30A line to your boat.
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Old 04-08-2012, 10:09   #11
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Re: How many 30 Amp inlets?

Yes it's hot here and the AC runs non stop in the afternoon. I turn off the hot water heater after morning shower. I've not been throwing any breakers and don't feel any excessive heat on the inlet, but I know I'm pushing it. Marina has new and very good power with 50 amp available. Seems like the easy way out it to run another 30 inlet to a 30 amp breaker and run the AC only off that inlet. If I understand this correctly I'll need to inlet, a double pole breaker and some wire. Mount the inlet, breaker and move the Air conditioner leads to the new breaker. Also would need another 30 amp shore power cord,

Am I missing anything?
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Old 04-08-2012, 10:11   #12
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Re: How many 30 Amp inlets?

Should also note that shore power is two 50 amp connections at the dock, so I will need another over priced 50 to 30 amp adapter.
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Old 04-08-2012, 10:11   #13
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Re: How many 30 Amp inlets?

Water heater should take all of 15 to 20 minutes to heat, then turn it off. You could probably run with that hot water all day. Too many people seem to leave their hot water heaters on all the time. Don't know why, it's not a house.

Turn your AC off for the 5-10 minutes you use your microwave.

Management is a lot less expensive than new wiring.

OOOPs you posted as I was writing.

Good luck.
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Old 04-08-2012, 10:16   #14
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Re: How many 30 Amp inlets?

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Originally Posted by Sailorman375 View Post
Should also note that shore power is two 50 amp connections at the dock, so I will need another over priced 50 to 30 amp adapter.
are those 240v 50 amp outlets?
you can get an highly overpriced Y splitter that accepts 50 and outputs twin 30.
I wonder how much the cost difference to buy the plugs and make a Y splitter.
perhaps $200 to get one already made/
http://www.wholesalemarine.com/p/MAR..._7cMAR_d_153AY
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Old 04-08-2012, 10:29   #15
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Re: How many 30 Amp inlets?

Pedestal has two 220/125 V 50 amp outlets. I don't understand the 50 amp stuff and know just enough about 120 30 amp to stay out of trouble. I know there is a difference between straight 220/ 50 and the 220/125 as I had to buy the correct adapter, but don't really understand the difference even after reading about it on Marinco's site.
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