On Monday, March 24, 2014 4:41:27 PM UTC-4, Mr. Luddite wrote:
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.

No, he doesn't need to understand anything about how his service is delivered! He just needs to understand that he has 2 hots and 1 neutral. If he wants 120 he uses one hot and the neutral. If he wants 240 he uses the 2 hots. He should always use the ground as ground if what ever he is connecting has a ground lead. That's it, end of story. He does not need to know any more than that.