On 3/24/2014 4:15 PM, wrote:
On Monday, March 24, 2014 3:41:13 PM UTC-4, Mr. Luddite wrote:
On 3/24/2014 3:26 PM, wrote:

On Saturday, March 22, 2014 1:33:11 PM UTC-4, da...@righthere... wrote:

On Tue, 18 Mar 2014 08:01:29 -0400, "Mr. Luddite" wrote:







On 3/18/2014 7:42 AM, KC wrote:



On 3/18/2014 3:34 AM, Mr. Luddite wrote:



On 3/18/2014 12:22 AM, KC wrote:



On 3/17/2014 7:57 PM, Mr. Luddite wrote:



On 3/17/2014 7:14 PM, wrote:



On Mon, 17 Mar 2014 18:19:42 -0400, KC wrote:







On 3/17/2014 6:01 PM, david@righthere... wrote:



I've been on 30A 120V power at the dock for years and would now like



to upgrade



to 50A 220V, or what they refer to as 50A 250V at the marina office.



I haven't



put a meter on it yet but so far suspect it's closer to 220 than



250. The socket



on the pedestal is like the one pictured he







http://www.catagle.com/68-153/CWD_Ar...uyersGuide.htm







They say it's 3-pole 4-wire. I'm guessing X and Y are the two hot



legs and W is



the neutral. Between X or Y and W would be 120V+/- and between X and



Y is the



220/250V. Right? How does the ground tie into it though? With only 3



poles do we



run a separate wire from the boat to the pedestal, and if so how do



we tie in?







Also can anyone suggest the cheapest place to get a plug like that?



So far the



best price I've found is $68.18 he







http://www.ktool.net/servlet/the-581...-63CR65/Detail























Thank you for any help!



David











The plug is 10-20 bucks at home depot or lowes, Scottys whatever you



have. It's a dryer plug basically... As to the wiring, I forget but I



have a book I always use when I do the wiring.. It was about 20



bucks at



home depot, I have had it for as long as I have owned a house...







Not true at all, sorry.







This is a non-NEMA twist lock 50a plug, that is corrosion resistant.







A dryer plug is a NEMA 14-30 straight blade that would go south pretty



quickly on a pier.















Yup. I think Scotty should stick to building websites and not wiring



boats.















Why, cause I took a quick look and made a mistake? I have done a lot of



wiring in my time including my whole house to code in Essex from moving



in with full Knob and Tube... I have done barns, and wells. When you



have a 100 year old house you tend to pick up stuff. You should see me



sweat a pipe.... even if I don't know all the right terminology. Either



way, that's why I always keep my electrical book with me to check my own



work as I go....











Scott, the OP didn't say if he was re-wiring his *boat* for a 50 amp,



240v marine split service. He might be just trying to use one leg of it



to supply 50 amps to his existing 30 amp, 120v boat panel. If so, he's



taking a big risk because it's not just the plug in question. The



primary feed wires in the boat that run from the power inlet to the



power panel needs to be changed at a minimum. Plus, if the existing



power panel has a 30 amp main, supplying it with 50 amps isn't going to



do him any good. If he changes that to a 50 amp breaker without doing



any changes to the wiring, he could overheat the primary feed wiring in



the boat, causing a fire.







My comment was more than pointing out that a split, 50 amp marine



service plug is not a dryer plug.







I did what I think he is trying to accomplish on the Grand Banks we had.



It had a standard, 30 amp, 120v service. I wanted to add two



air-conditioning units to the boat. Rather than change everything over



to a 50 amp, 240v split service I simply added another 30 amp, 120v



marine inlet connector, wiring (marine type) and a small, dedicated



breaker box with two 15 amp breakers in it, one for each of the AC units.







After talking to a guy at West Marine that's the type of thing I'll do too if I



follow through with it. I might add a couple of extra outlets too, in case I



want to run an extra heater in the winter without tripping the main as I do from



time to time.







I will want to have 240V available though. I did stage lighting for years and



have been given some old moving lights that need repair and the place I work



doesn't want to put the money into them. They are old Martin Mac 500s and 600s



and they only work on 240V (+/-) power. So what I mainly want the 240 for is so



I can work on them and try to get some of them going again. My question is: If



the marina hooks up another 30 amp sevice, will it be out of phase with the



original one or could it be in phase? It wouldn't do me any good if it's in



phase, so would I need to specify or would it be out of phase and I don't need



to bother them about that detail, do you know?







I don't know a lot about many things and nothing about some things



however electrical power distribution and wiring happens to be one thing



I *do* know something about. I'd hate to see someone hurt or killed



because they received bad input.







Now, I have a question for you. Let's say your house has a 200 amp



service. Your main breaker is a double pole, 200 amp per pole breaker.



There's 240vac between the two "hot" legs and 120vac between either of



them and neutral. Each hot leg from the utility pole is sized for 200



amps for each side of the service, yet the neutral is also only sized



for 200 amps. Why isn't it sized for 400 amps, the sum of both sides of



the total service?







See if the answer is in your "electrical" book.







Is this a job you are gonna' do yourself? snerk











No, it's not a job. It's a question. Can you answer it with all your



experience wiring homes, barns and whatever?







Look, any handyman can do basic wiring in their house. It's not rocket



science. But knowing something about current capacities, codes and



particularly how the power in a house, commercial building or a *boat*



is distributed requires more than a handy dandy DIY book from the Home



Depot.







I am not an electrician. I am an electrical engineer. If I wanted a



new power service installed in my house or was doing a major upgrade to



the existing service, I'd hire a licensed, master electrician to do the



job.







BTW, the answer to the question I asked is because the two "hot" legs



are 180 degrees out of phase relative to each other, so the net current



flowing through the neutral leg adds algebraically. The current through



the neutral leg can never exceed 200 amperes.







Thanks for sharing that. I still have the question of whether the the two 30 amp



120s would necessarily be out of phase though, even though what you wrote leads



me to believe they probably would be.



The "phase" of conventional residential is debated a bit as some don't think it is two phase and some do.



The important thing for you is that 240v service will have 2 hots, 1 neutral, and 1 ground. Between either of the hots and the neutral you will see 120vac. The same 120vac you are using now. Between the two hots you will see 240vac.



Your biggest problem is that your current panel inside the boat most likely only accomodates 1 hot, 1 neutral, and 1 ground. If that is true you really need a new panel to safely use the 240vac 50amp service. The regular service breakers you have for outlets and lights are typically distributed evenly between the two hots. Any 240vac connections like heat will use a ganged breaker connecting to both hots.



Now you likely do not have to take advantage of the new power at the dock if you don't want to. Simply ignore one of the two new hots. Connect one hot, one neutral, and one ground to your existing setup. Presuming you have a 30amp main for the one hot. Or you make sure everything between the panel and the shore can handle 50 amps.



Do you have a "main" breaker inside that turns off everything? If so, how many amps is it?



It is very unlikely that you have 3-phase service btw. That's commercial.







I've heard electricians refer to a residential service to your home as a

"split phase" service. I agree there is some confusion as to calling it

"two phase" however, as you correctly state, it does have two hot legs

that are 180 degrees out of phase with each other. In my mind that

means there are two, out of phase hot legs. A 3 phase commercial

service would have three hot legs that are 120 degrees out of phase with

each other.



I agree that the OP's actual service to his boat at the pedistal is not

3 phase however the distributed service to the marina could very

likely be a commercial, 3 phase service. It could also be a split phase

like a residential service however depending on the marina size.

Regardless, if the OP wants to get something close to 220vac for testing

his stage lights, he's going to need two hot legs.

The possibility of 3 phase commercial service somewhere in the marina is immaterial.
In this case bringing it up only creates the possibility of confusing
the op.
His 240v 50amp service at the dock will be the same as is found in US
residential homes.

So? I don't understand how that changes anything. He still needs a
second hot leg, either from a distributed 3 phase system or a split
phase system. He acknowledged that he's not trying to change the
service in his boat from a 120vac, 30 amp service to a 250vac, 50 amp
service. He just wants 208vac, 220vac or 240vac to test some stage
lighting. Understanding how that service is delivered is important to
his intended purpose, don't you think, especially if he is not an
electrician as I suspect?

I stand by my previous comments, including my suggestion to employ the
help of a licensed electrician if he is not familiar or sure how it is done.