30 amp Power Cord Problem

L

Lawleys

New Member
Apr 1, 2012
5
Carrabelle
Boat Info
1988 Searay 300 Weekender
Engines
2 5.7 liter Mercruisers (Gas)
I have a 1988 weekender and have "finally" replaced our hot water heater. The issue I am having is if I run the A/C and hot water heater at the same time... I am using about 25 to 30 amps. I know this is right at the limit of my shore power but one lead of my cord melted. Not something you wanna see on your boat. I thought the problem was I had an older 30 amp power cord and maybe it wasn't getting a good connection so I bought one of those new fancy EEL cords. and the next week the same lead was melted as well.
I have a couple questions.
1. why is my power cord lead melting (on the boat side)?
2. Is there something I can add to avoid this? I have seen newer searay boats with a Y adapter with 2 plugs on the boat.
I am asking the obvious but want to make sure something else is not going on here.
Thanks so much for any help on this issue,
Scott
 
In addition to the fact that you are running at the limit of the cord's amperage rating, perhaps the receptacle on your boat is bad and making a poor connection with your cord end. One contributing factor for this could be due to plugging in and out under load instead of shutting off your main breakers first.
 
Happened to me....replace the boat side inlet and the power cord plug.....all good.
 
How long is your cord ?
Picture a garden hose & compare to an extension cord. Longer it gets the less pressure you have at the user end. Water pressure will drop from losses in the hose. Voltage will drop with resistance losses over distance.
120V at one end could be closer to 100V at the user end. Appliances are looking for "wattage"- volts X amps. Voltage drop will spike current flow to satisfy the appliance.
As "electricaldoctor" posted above, make sure you connect/disconnect with no load as the contacts will arc under load. Arcing is actually welding, damaging the contact points on the male/female connector components. Poor connections will generate more resistance, leading to more heat, leading to more damage at the contact point. Snowball effect takes over from here.
What voltage are you getting from the pier connection point ?
 
I think Electricaldoctor is on the money. Ever since I saw a friend's plug melt, I have been a beliver in turning off the power BEFORE disconnecting the power. Every time you unplug with the power on, there's a spark. After time, the connection will begin to corrode...then overheating occurs. I too, say, change the plug and get a tight connection.

Don
 
Did you check for loose connections at the rear of the boat receptacle?...On older boats I would also check the terminals at the main breaker (better yet, all breakers) for looseness as prevenative maintenance. Seen the loose connection/melted wires/smoke scenario a couple times.
 
Just a side note to the 30 amp cord/receptacle issues, we try not to load our circuits beyond 80% of any breaker's rating. We just don't like living on the edge. There are always other alternatives and all of the components within the circuit will last longer. Keep us posted on your remedies to your "current" problems. :grin:
 
if this problem just started when you changed the water heater, then the problem is right there. both the water heater and a/c should not be drawing anything close to 25 amps whether running together or separate. double check the polarity and connections at your water heater. mine draws around 8-10 with both running
 
The current draw may be high, but the highest priority problem right now is that the cable is overheating and the breaker is not tripping.

You have one of a couple possibilities happening here.

Your main breaker may be stuck, allowing more than 30 amps to flow through the cord. Possible, but not likely.

You have a loose connection creating resistance (heat) and melting the cord. This scenario is more likely due to the main breaker not tripping.

The breaker's job is to prevent damage to the wiring. Right now it's not doing that. You need to fix that problem first, then address wether or not your water heater, a/c, TV, leaf blower... Are drawing the appropriate amount of power.
 
I run my hot water heater with the AC running a lot and have never had a problem. I'll have to check, but 25 - 30 amps seems like a little higher than I remember mine drawing when they are both on.
You might have another problem somewhere besides the receptacle.
 
No, my 320 had a single 30a arrangement. It's all based on the load needed for each boat. The problem, as I see it, is a bad receptacle on the boat side. If there is a loose connection it will generate heat when energized under load. Not only will the heat caused by minor arcing ruin the cord, it will seem like additional load and can tax your system and cost more in power bills. Replace the receptacles and always screw in the keeper nut to hold the cord tight to the receptacle to help prevent the connection from becoming loose and causing this issue again. I actually have one on the verge of going bad and will be replacing both very soon to eliminate this potential issue.
 
I just replace the connectors on both of my power cords. The female side of the connector had turned brown because of a loose connection that caused arching. The problem actually was in the male side of the connector on the boat. If you make the repair be sure to replace both the plug and the receptacle or you will probably have to do it again.
 
Finally got down to the dock to spend some time on the boat. It was closed up all week, unplugged, battery switches off, and in a record heat wave since last Sunday.
Plugged in the shorepower cord and then went in to turn on the breakers.
First thing I turned on and started up was the AC. The gauge jumped to 14 amps.
Next was the hot water heater, the gauge jumped to 24 amps. Then I did the outlets, fridge, and AC converter. I turned on the battery switch and cabin lights and water system breaker. Then I plugged in two small 110 fans I keep in the cabin.
Everything going, I got to 26 amps. Checked again a while later after giving the water heater a chance to get the water up to temperature, and I was back down around 14 amps.
It's really hot and humid here this afternoon so the AC compressor will probably be slaving the rest of the day.
If you are pulling 30 amps or more with just the AC and hot water heater you might have another problem.
My AC, fridge, hot water heater, stove, and AC convertor are all original equipment and probably a lot less efficient than newer stuff.
My microwave is not original, and the boat didn't come with one installed from the factory.
 
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