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Author Topic:   Supplying Power to Electric Trim Tabs
Dave Fahy posted 05-20-2014 09:50 AM ET (US)   Profile for Dave Fahy   Send Email to Dave Fahy  
I am about to install Lenco trim tabs on a 1999 Boston Whaler Conquest 21. It has not had tabs before so the wiring is not already there. The three "ACCS" switches are only 10-Ampere. Do I need to add a switch to the bus bar that has 20-Amperes? How do I wire this? Thanks
jimh posted 05-20-2014 10:58 AM ET (US)     Profile for jimh  Send Email to jimh     
Dave--I suspect that the devices you call "switches" and assign a current rating of 10-Amperes are probably actually circuit breakers. They are the over current protection for branch circuits that distribute power from the primary power distribution to the helm area.

To know if you can use one of the 10-Ampere branch circuits of the "ACCS" group to provide power to the Lenco Trim Tab actuators, you have to find out how much electrical power is needed by that load.

Check with the manufacturer to see what the power requirements are for the load. If the load is 10-Amperes or less, you can use one of the existing branch circuits with the 10-Ampere circuit breaker. If you need a circuit with more capacity, you must make a modification to the electrical panel.

One option may be to replace one of the existing 10-Ampere circuit breakers with a new circuit breaker of the same style and type but with a higher current rating. Here I am assuming that one of the existing 10-Ampere circuit breakers is presently not feeding any loads and is unused.

If you do not have any unused branch circuits, you will have to install a new branch circuit. To install a new branch circuit you will need a new circuit breaker, and some place to install it. Often there are blank and unoccupied cut-outs on the circuit breaker panel that are ready to be used for installation of a new branch circuit.

When connecting an electrical load to the branch circuit power distribution at the circuit breaker panel, you must use proper wiring practices, and select the conductor size to be appropriate for the length of the circuit and the current that will be flowing. This is necessary to keep the voltage drop on the circuit to be acceptable.

Let's start with the first step: how much electrical current is needed by your new load?

Dave Fahy posted 05-20-2014 04:12 PM ET (US)     Profile for Dave Fahy  Send Email to Dave Fahy     
That does not seem to be listed in the spec, I believe each one can use up to 5.1 amps. Having to add an inline fuse is not an issue. My problem is I would like this to be a product I can power on or off independent of the engine starting. There is a neg, pos and an orange ignition positive. How do the Conquest 21's that came with Bennet tabs hook up?
jimh posted 05-20-2014 05:50 PM ET (US)     Profile for jimh  Send Email to jimh     
Do you have the factory wiring diagram? These are often posted at WHALERPARTS.COM. You might also get a PDF copy via email from Boston Whaler customer support.

If each tab actuator can draw 5-Amperes, and since you can activate them simultaneously, the circuit providing the power to them should be fused or have a circuit breaker of at least 10-Amperes, possible 15-Amperes to give a bit of margin so the fuse or breaker does not open on routine operation.

Sometime accessories like TRIM TABS might have a circuit to sense the engine ignition switch so the tabs return to a certain default position when the engines are off. You can usually wire into the ignition switch circuit right at the helm.

jimh posted 05-20-2014 05:53 PM ET (US)     Profile for jimh  Send Email to jimh     
Whether you want to connect this accessory load to a circuit breaker on a circuit breaker panel or if you want to wire it directly to a distribution bus and use an in-line fuse depends mostly on how you want to handle this expansion of loads on your power distribution. Generally it is considered better and more consistent to follow the method used in the initial boat construction. If the boat has a circuit breaker panel and has circuit breakers for each branch circuit and load, then it seems preferable to continue in that same method when expanding the electrical distribution.
Dave Fahy posted 05-21-2014 10:52 AM ET (US)     Profile for Dave Fahy  Send Email to Dave Fahy     
I do have the electrical diagram. It only lists the amps per breaker and not what is usually on each. I believe the Conquests with the Trim tabs originally included had an additional breaker on the panel.
jimh posted 05-21-2014 12:57 PM ET (US)     Profile for jimh  Send Email to jimh     
From you comments, it sounds like adding a new breaker is probably called for, or, if one of the 10-Ampere ones is not being used, try that as a start. If the breaker blows all the time, you can just replace it with a larger one. Boston Whaler customer service can very likely provide you with more information about the details of the trim tab accessory and how it was wired.
swist posted 05-22-2014 09:14 AM ET (US)     Profile for swist  Send Email to swist     
How are you planning on running the wiring?
Dave Fahy posted 05-22-2014 04:47 PM ET (US)     Profile for Dave Fahy  Send Email to Dave Fahy     
I originally thought the power and ground should be run off one of the accessory breakers with the retract feature connected to the ignition. Since it needs a 20amp fuse it probably makes more sense to run it of the pos and negative bus from the helm and the ignition switch using an inline 20 amp fuse. The accessory switches are only 10 Amp.

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