Cable Runs For Boathouse Boatlift

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Old 04-08-09, 07:15 AM
J
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Cable Runs For Boathouse Boatlift

I plan to install a boatlift in my boathouse and need to update the old electric that was run to it. The boatlift motor will require about 5.5 to 6 amps at 240V. There are 2 UF cables that were originally run all the way from the house main panel to the boathouse, which is about 185' away. These cables are 12/2 ga and 10/2 ga, each with bare copper ground conductor. They were in bad condition under the pier, so I cut them back to the point where they exit the shoreline to the start of the pier. I tested them at that point and they seem OK.

Apparently, someone had also installed a subpanel at the boathouse at some later time. It is fed with 8/4 ga (insulated ground) that is in plastic conduit. There is a junction box at the start of pier where this cable is join to another cable via wire nuts. Since the cable going from the junction box to the house looked very suspect (like a heavy duty appliance extension cord), I pulled it up a little. It seemed to be buried shallow, so I kept pulling and found....get this....it terminated a few feet away to a 120V plug! It never ceases to amaze me what people will do! Well, I was going to abandon the junction box anyway, since it was filling up with water at very high tide, so I'm trying to determine my next step.

I was planning on abandoning the 8/4 cable and subpanel at the boathouse, since the 10/2 cable does not have a neutral conductor to feed the subpanel. The subpanel also does not have a single main breaker in it. So, I thought I'd either bring up the 10/2 and 12/2 to a disconnect box on shore just before the pier, or do underground splices, probably with resin/expoxy versus heat-shrinkable tubing, and run them out to the boathouse. There, they would go to either a) a disconnect at the boathouse, or b) to their respective terminal devices -- a boatlift switch with GFCI for the 10/2, and a GFCI outlet for the 12/2. The GFCI outlet would probably also feed a couple of lights. Back at the house would be a 20A 2-pole breaker for the boatlift and either a 20A (or 15A due to voltage drop) 1-pole breaker for the GFCI outlet.

So, here's my questions:
1. Am I correct in thinking a subpanel is not an option without retrenching new cable with more conductors?
2. Should I use a disconnect box, and if so, where should it be located? I'm assuming I can combine both circuits/breakers in a single box.
3. Is the 185' run from the house too long for my current plans? I'm getting mixed feedback from different sources. Also, would it help to splice larger gauge cable from shore to boathouse to help reduce voltage drop?
4. As for the future, if I add another boatlift (or 2?), can the boatlift circuit described above handle it? How would it be tied in?

Your time in looking at this is greatly appreciated.

Thanks,
Jack
 

Last edited by jaksprat; 04-08-09 at 07:31 AM.
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Old 04-08-09, 06:50 PM
Tolyn Ironhand's Avatar
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The issues I see with your plan is that a detached building may have only one feed. You may use either the 10/2 to run your lift or 12/2 to run your light and general purpose GFCI's.

If it was me, I would run a new feed and refeed the sub panel that was already in the boathouse (if it is in good shape and is big enough). Sadly, that would involve trenching from the house.

Just for note - the sub panel does not need a main if there is 6 or less breakers in the panel. If you do have more than 6, you can always back feed a breaker and mark that as your main.
 
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Old 04-09-09, 05:20 AM
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Thanks for your reply Tolyn. I appreciate your point that there should be only a single feeder, but I thought there was an exception that I could make use of. Here's the NEC reference [note item (D)]:

'225.30 Number of Supplies. Where more than one building or other structure is on the same property and under single management, each additional building or other structure that is served by a branch circuit or feeder on the load side of the service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (E). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit.
(A) ...
(B) ...
(C) ...
(D) Different Characteristics. Additional feeders or branch circuits shall be permitted for different voltages, frequencies, or phases, or for different use, such as control of outside lighting from multiple locations.'

Since the boatlift and GFCI outlet are different voltages (240 vs 120) and they are for different uses, do you think it qualifies for this exception?

Also, it may not make a difference, but the boathouse is not really a 'building', since the sides are all open. It's basically just a roof attached to 6 pilings, so I interpret it to be a 'structure'. Another question is whether the pier and boathouse are separate structures. For now, it probably doesn't matter cause the GFCI outlet and lights will be under the boathouse roof, but I may add another boatlift later on the other side of the pier, which could be considered a separate structure.

Again, thanks for your comments.

Jack
 
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Old 04-10-09, 12:10 PM
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It is my understanding that the exception that you sited is for different systems in commercial buildings. Such as 120/208Y and 277/480Y. Your feeds are different voltages but they are voltages of the same system as part of this quote:
For the purpose of this section, a multiwire branch circuit shall be considered a single circuit.
Of course this is all up to the AHJ.

IMO - "Building" and "structure" are the same thing.
 
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Old 04-13-09, 04:39 AM
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Thanks, I'll keep that in mind.
 
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