0

I replaced my 2 boatlift motors with new ones that are each rated for 15amp starting & 11amp continuos,, this takes a total of 30amp starting & 22amp continuos & after a few seconds they trip my 20amp breaker, so I was thinking of just replacing the breaker with a 30amp instead of having to replace the wiring running thru my attic all the way to my boatlift.

New contributor
Juan is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
9
  • 4
    Ideas of this type is why there is an electrical code. Plug in a toaster and kettle, trip the breaker. Put in a bigger breaker and the house burns down. Check what wires you do have first, 12 gauge limits you to 20 amps. Might be lucky and have larger gauge because of the distance.
    – crip659
    Sep 21 at 12:53
  • 6
    Can you live on the boat? Because you're going to burn your house down. Sep 21 at 13:01
  • 1
    @manassehkatz - That's what I had to do before re-wiring my dock. Start one motor, then the other (no choice there since the switches were mounted on the covers). They would both run for maybe 20 seconds, then the single 15A breaker would trip.
    – SteveSh
    Sep 21 at 14:26
  • 2
    Your mentality of "just change to a bigger breaker" is dangerous. With that mentality, why even have circuit breakers at all? That said, is the boat lift the only thing on the circuit and do the motors have onboard overvoltage protection? What does the boat lift documentation say? Can you change to smaller/the correct motors? Do you really need to use both boat lifts at the same time? Sep 21 at 19:31
  • 1
    You chose to replace the motors with larger motors; perhaps after you replace the breaker with a larger breaker while not also using larger wire (and pulling a permit) and find out after your house burns down that choosing to do that invalidated your fire insurance coverage (it's practically arson...) you'll learn a thing or two about making choices.
    – Ecnerwal
    Sep 22 at 1:48

3 Answers 3

8

Only if you like electrical fires.

The reason that we use breakers in the first place is to prevent wires from being dangerously overloaded.

Compare the wire for your cell phone charger to the wire for your electric oven, electric dryer, air conditioning, or other large electrical device. Notice that the phone cord is super small and the oven cord is pretty chunky? That extra thickness is because the oven uses a lot more power than your phone. If you tried to splice your phone cable into your oven's wiring, and turned on the oven, the phone cable would overheat instantly and quite likely melt and catch fire.

The difference between a 20A circuit and a 30A circuit is not quite as dramatic, but the same principle still applies: to carry more current, you need thicker wires. That's just physics, there's not much wiggle room there. Your breaker is tripping right now to prevent a similar melt-and-catch-fire scenario from happening within the walls of your house.

There are a few possibilities that could work with the existing wire:

  • Can you replace your motors with 240V versions? At 240V instead of 120V, you can get double the power for the same number of amps! At 240V, you'd have a 4800 watt limit instead of your current 2400 watt limit, using the same 20-amp-rated wire and a double-pole 20A breaker. You'll need to replace all of the outlets on this circuit with the proper 240V outlets as well.
  • Did the guy who originally ran the cable put in a thicker gauge than necessary? (Extremely unlikely due to the cost reasons you've already discovered, but couldn't hurt to check.) If you can post photos of the markings on your existing wire, someone can help you identify if it's thick enough or not. Note, however, that you must be able to determine for certain that the wire is oversized along the entire length of the run - otherwise, that one smaller section will have the same melt-and-catch-fire problem. Note: see my edit below, there may be problems with this solution.

If neither of those options check out, then running new wire is going to be your best bet.

EDIT: A 30A circuit may be out of the question, period. You cannot have NEMA 5-15 or 5-20 receptacles (aka "normal 120V receptacles") on a 30A circuit, it's a violation of the instructions which are part of the UL certification. (You care about UL certification because if something goes wrong and the insurance company finds out, they might reject a claim because you used it in an illegal manner.) If your boat lift motors are hard-wired (no receptacles involved), they may have a point in their instructions which may state that it is protected by a 20A or maybe even 15A breaker. If that's the case, then your only option is to run a new, separate circuit for the second motor, keeping the first motor on the existing circuit.

If these motors plug into a receptacle, or if there are other receptacles on this circuit, or if the motors require a 20A or 15A breaker to protect them, then you'll need to run a new 15A or 20A circuit to one of the motors (and using the existing circuit to power the other motor). On the bright side, the cost for 14 or 12 gauge cable for the new circuit will be less than the 10 gauge you were looking at initially.

1
  • Interesting part about 240 V motors. Some motors, I think, allow you to change from 120 V operation to 240 V operation just by swapping some wires inside the access cover of the motor.
    – SteveSh
    Sep 21 at 13:56
4

No, because you probably only have 12 gauge wire running from the breaker to the boat motors. 12 gauge wire needs to be protected with a 20 A (max) breaker.

I had a similar situation, but I had two circuits out to the dock. So I was able to run another UF cable out to the motors and have each motor on it's own breaker and feed from the house.

Here's a earlier post very similar to you situation GFCI's on BLACK/RED dual 15-amp circuits.

2

Right now I have to run one boatlift motor at a time,

Well yeah, because you enlarged the motors without thinking about electric service.

I really don't quite understand your situation. Do you have two boat lifts for 2 boats, and want to run them both at the same time for some reason? Don't.

Or do you have 1 boat lift with a motor on each end of the boat? If so, hacking the machine to use a larger motor was a serious blunder. It isn't faster; motor speed is the same. The machine may not be electrically able to handle the additional power, and it could fry stuff. If you fit larger motors because your boat is too heavy, you may be physically overloading the boat lift also. You should really consult with the factory or an engineer on any modifications to the boat lift.

Hi again, so what would be my best inexpensive way to fix this problem?

Install the correct motors. If you haven't thrown out the old motors, many motor shops can rebuild motors.

Every alternative solution is going to involve either installing a battery system out there, or trenching new conduit to install a new cable (I assume the original cable is direct burial, since you wouldn't be complaining if it was in conduit).

Hmm, battery.

The battery answer doesn't sound so bad costwise. To understand why, you need to learn the difference between power (flow of energy in that moment) and energy (total work done). Power is how fast you are using the energy.

The boat lift takes a lot of power, but only for a very short time which means it uses very little energy. Suppose it uses 2600W for 1 minute. Thats 2600 watt-minutes or 43 watt-hours. Well heck, a typical golf cart battery is 1000 watt-hours.

So you don't even need new ones, just hit a golf cart battery seller and ask for trade-ins that can't make it 18 holes anymore. Get them cheap.

A 100W battery charger will replenish the battery from 1 boat lift cycle in a half hour. Your circuit can handle 100W.

I would want 2 or preferably 4 batteries given the high surge load. 12 volts or 24 volt system.

The only trick is the AC inverter. It will need to be quite large to start both motors. But it only needs to run when the boat is lifting.

Oh and by the way, did I mention? If you come back from boating and the AC power has failed, you can still lift your boat.

3
  • The battery+inverter part sounds overly complicated. I've never lost power to run the lift in over 12 years. If that happens, just tie the boat up to the dock.
    – SteveSh
    Sep 22 at 0:03
  • @SteveSh Maybe, but OP's criteria don't forbid complicated and do forbid costly. "cheaper than trenching a new circuit" is plainly stated, and I also infer "cheaper than replacing motors again". Sep 22 at 1:24
  • 2
    maybe swich to DC motirs instead og getting an inverter.
    – Jasen
    Sep 22 at 10:37

Not the answer you're looking for? Browse other questions tagged or ask your own question.