220v & 110v setup for dock

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Old 02-03-19, 07:12 AM
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220v & 110v setup for dock

Hi guys, brand new member looking for advice. I'm an experienced DIYer but definitely out of my depth with electrical so not looking to do this myself. However, I live on a Caribbean island where I need to be able to clearly explain what I want to the electrician or will get a 'standard' set up that doesn't meet my needs - and I need help knowing what to ask for so here I am. I also have to be my own 'code conscience' as there is no code or inspections here. Just as background I have received quotes so far that range from $4,000 - $10,000 for my setup with all kinds of different proposed configurations.

Here's the situation, I am building a new house that has a 25kw transformer and plenty of spare panel capacity. I am looking to run a circuit to a dock to power a boat lift, lights and outlets. The boat lift can operate on a 220v or 110v circuit and I want to use 220v for a number of reasons, not least the fact that I need a 650 foot run from the house to the dock. The boat lift has 2x 3/4hp motors and the specs require a 15A breaker on a 220v circuit. It will only be run for a few minutes at a time and it's highly unlikely there would be any other demands on the circuit at the time.

My 110v requirements will be permanently wired LED lights for both the dock and underwater lighting. They are designed to run on a regular 110v circuit (i.e. transformer built in) and total power draw if everything is on will be no more than about 700w so less than 7 amps. I'll have a couple of outlets for occasional use - phone chargers, or similar, but no big draw.

Cable will be run underground in PVC conduit to the beach and then attached to the underside of the dock.

I know I need THWN cable, and my plan is to run it in PVC as much as possible - i.e. attached to the underside of the dock as well as underground. I would like to avoid having any kind of box at the dock for security and because of the saltwater environment, but I'm not sure if that's possible with my 220v and 110v requirements. Switching will be from the house to allow power to be cut to the dock completely when not in use. So here are my questions:

1) Is there a way to safely have 220v and 110v without a breaker? It has been suggested that running cable with two hot wires will allow that to occur safely through a multi wire branch circuit but I'm getting conflicting opinions on that.
2) What gauge cable do I need for a 220v / 15a / 650 foot run? Again, more opinions than I can deal with and I need validation - I believe it should be 4 AWG but am happy to be educated. Also, I am being told by some I should use aluminum instead of copper - but no one can tell me why other than "it's better" (so that's helpful). I also have some quotes for 1,300 feet of cable - i.e. two runs and I have no idea why.
3) I'll put a GFCI breaker in at the house panel but assuming I should also have GFCI outlets on the dock?
4) What else should I be asking about / know that I'm too dumb to realize?

Sorry for all the questions as soon as I get here, hopefully they're not too dumb!

Thanks so much for reading this.

Andy
 
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Old 02-03-19, 07:59 AM
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s there a way to safely have 220v and 110v without a breaker?
No. The wire needs to be protected where it originates. That means you need to install some kind over current protection at the panel.

What gauge cable do I need for a 220v / 15a / 650 foot run?
#6 copper will likely be fine as all the loads will not be running at the same time. You can go larger if you choose. I would not use aluminum due to the salt water and voltage drop.

I'll put a GFCI breaker in at the house panel but assuming I should also have GFCI outlets on the dock?
You are not required to GFCI protect the branch circuit, only the receptacles.

I know I need THWN cable, and my plan is to run it in PVC as much as possible
You are required to use PVC conduit the entire run if you use THWN conductors. Only cables can be run without conduit.

I would recommend running a multiwire circuit (2 hots, neutral, ground) down to the shore and then installing either a small panel or just a junction box using 3 #6 THWN wires and 1 - #10 wire for the ground. Then continue from there with the branch circuits to the dock. IF it is a panel you can install any GFCI's there, and can split the circuit up between the 240 volt and 120 volt circuits. Those wires can also be smaller as the distance will be much shorter.

The real issues I can see is how easy it will be to bury the conduit and install the wires, and finding wire available 600' long
 
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Old 02-03-19, 08:20 AM
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Thanks for the rapid reply (on a Sunday). I think I can solve the burying conduit issue fairly easily - labor is cheap here so a few enthusiastic guys can trench it fairly quickly (and it's all my property). I am told by the hardware supplier on the island they can get 1,000 foot cable spools, but taking your suggestion of running the multiwire circuit only to the beach I could actually get away with a 500 foot spool between the panels.

Am I understanding you correctly that I don't need conduit if I use THWN cable?, that's a pleasant surprise.

So then it sounds like I should be looking for:

1) Multicircuit #6 for around 480 feet to the beach
2) Panel at the beach
3) a 220 and a 110 circuit from beach to dock again using #6 THWN
4) GFCI outlets

I'm assuming 15A breaker at the house and on the 220 side of the beach panel and smaller (10A?) on the 110 side of the beach panel .
 
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Old 02-03-19, 09:58 AM
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You are required to use PVC conduit the entire run if you use THWN conductors. Only cables can be run without conduit.
You misread what he wrote. You DO need conduit.

In your case..... I would only use PVC and not use a buried cable.

Not 100% sure what you have there but you will be running a single conduit with 3) #6's and 1 #10 from your house ? to a sub panel at the beach. From the sub panel you can use smaller wire to your receptacles. I would use a GFCI breaker as opposed to GFI receptacles due to the salt air.
 
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Old 02-03-19, 10:08 AM
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THWN is an insulation type.
A cable is an assembly of conductors in an overall sheath or bundle.
 
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Old 02-03-19, 11:35 AM
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1) Multicircuit #6 for around 480 feet to the beach
3 #6 conductors (hot, hot, neutral) and 1 #10 for the ground

2) Panel at the beach
Correct

3) a 220 and a 110 circuit from beach to dock again using #6 THWN
240 volts and 120 volts. You will likely not need #6 for the branch circuits, just for the feeder to the panel. I would recommend using #12 using a 15 amp breaker for each circuit. At the house panel you could use any size breaker that is not too large for #6 wire. I would recommend maybe a 2 pole 30amp.

4) GFCI outlets
I would also agree with PJ and install GFCI breakers in the beach panel.
 
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Old 02-03-19, 04:05 PM
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Thanks everyone, I really appreciate it. I feel much more confident having a conversation with the electrician now.

THWN is an insulation type.
A cable is an assembly of conductors in an overall sheath or bundle.
Yeah, I get that. I was under the impression I could get a cable that contained two hot, one neutral and an earth conductor that was rated as THWN - i.e. a PVC coated cable containing PVC coated conductors (where the upgrade to PVC coating provides the THWN rating), my bad. More evidence that a little knowledge can be a (literally) dangerous thing.
 
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Old 02-04-19, 04:06 AM
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UF is a cable that is rated for outside and direct burial, no conduit required. The largest conductors I have see UF have is #6 but I am sure they make it in larger sizes if needed. Only thing about UF is it needs to be protected by conduit when it leaves the ground. (IE: protected from physical damage.) That might be easier then pulling 500'+ of wire in conduit. UF is required to be buried 24" in the ground.
 
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Old 02-04-19, 05:10 AM
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UF is a cable that is rated for outside and direct burial, no conduit required. The largest conductors I have see UF have is #6 but I am sure they make it in larger sizes if needed. Only thing about UF is it needs to be protected by conduit when it leaves the ground. (IE: protected from physical damage.) That might be easier then pulling 500'+ of wire in conduit. UF is required to be buried 24" in the ground.
Thanks, I'll see if I can find a supplier for that here. Pulling the wire through conduit isn't that big a deal as it would be laid at the time of install so there won't be a need to pull a full 500 feet as a single run, but it's really going to come down to what is available here. Depth of trench also isn't a big deal - the advantage of beachfront is sandy soil :-)
 
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Old 02-04-19, 05:19 AM
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The raceway is required to be complete before the wires are pulled in. You can't just pull it in 10' at a time. It is too easy for the wires to get damaged that way.
 
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Old 02-04-19, 06:57 AM
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Oh, okay, didn't realize that, though I guess it makes sense! Thanks, you guys have been really helpful!
 
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