Shore Power

Transformer must be unique to boats system (EU). As far as 555.19, I think that is for 120/208, 120/240, difference in plugs and equipment. Verify boat voltage requirements if you can to be sure. Give him a price and take his money.

 

Just to follow up, I spoke with the chief EI in a city near the water and he discussed it with the plans reviewer and they both agreed that that transformer would not meet the intent of 555.19.

I also could not make the "designer" (who I'm told is an engineer) understand he cannot use 200-amp OCP on #1/0 and #2/0 conductors feeding the marina pedestals.

Am I wrong to be concerned about feeding 120-volt circuits with a 127-volt source?

 

I was just sent a set of drawings for a marina and the "designer" (I'm not sure he is an engineer) is calling for a 3-phase transformer on the dock to step voltage from 480/277 to 220/127 (the transformer is wound to deliver this voltage instead of 208/120).

The load side of the transformer will feed 50-amp 125/250-V receptacles (for shore power for boats) as well as 120-V 30-amp receptacles (for shore power for boats as well as general purpose receptacles and lights).

If you look at 555.19(A)(3), it tells you not to feed the 50-amp 120/240-V receptacles from a 208/120-V source. So, how do you feel about feeding this receptacle with a 220/127-V source (I personally don't like it, but I'd like to hear from y'all).

I don't like that arrangement as well there will be some conflect with the voltage rating on shore power source due some of the vessel the small to med size vessel typcially use single phase shore power the larger one tended to use triphase source (just watch the voltage rating on them ! :blink: )

Also try to run 208 volts on 240 volt system some of the equiment will not work on that voltage at all ( this will compounded if you get European speced vessels come in )

I also have concerns for the 120-V loads being fed at 127-V. The power company says it's voltage can fluctuate +/- 5%. So, if you have 127-V at normal PoCo voltage, you have 133.35-V at PoCo voltage of +5%. I've always heard that equipment works fine at +/- 10%, so 120*1.1= 132-V. Now, 133.35 is not that much more than 132, but it doesn't sit right with me. Voltage drop will help with the over voltage, but still.

What other concerns am I missing? It just really doesn't quite seem right to me to feed these receptacles from this power source.

Thanks,

Just to follow up, I spoke with the chief EI in a city near the water and he discussed it with the plans reviewer and they both agreed that that transformer would not meet the intent of 555.19.

I also could not make the "designer" (who I'm told is an engineer) understand he cannot use 200-amp OCP on #1/0 and #2/0 conductors feeding the marina pedestals.

Am I wrong to be concerned about feeding 120-volt circuits with a 127-volt source?

I will just stay away from 127 volts source much as possible due most of the Americian vessel are rated to take 120 volt source but 127 volts is pretty much on borderline for some vessel but some other it will not affect.

Merci,
Marc

 

I have worked at a lot of marinas and have only seen 120/208Y. You bring up a good point about 555.19 (a) (3) but I have never seen it followed.
I have never seen a delta service at a dock or any specially wound transformers.

The load side of the transformer will feed 50-amp 125/250-V receptacles (for shore power for boats) as well as 120-V 30-amp receptacles (for shore power for boats as well as general purpose receptacles and lights).

If you go by the letter of the code where will you get 125/250v? You are right though and the FPN confirms it.

 

If you go by the letter of the code where will you get 125/250v?

That's the rating on the receptacle (125/250), and you're right, I can't get that voltage, although I often see 123/246 from the PoCo.

 

I fixed one marina that had 208Y/120 (a service change that cost them $17,000.

I know of another that was bigger and they paid big time to change out to single-phase delivery. Anyone that puts in a 208Y/120 service to feed 50-amp receptacles is ignorant of the problems it creates.

I've never had a issue running 50 amp receps on 208y. But then again I haven't done any marina work. Keep vd drop to a min. What's the issue. I can't see how something on a boat would be that sensitive most are set up with batteries and a inverter/converter like a rv right?

 

The wire length from the transformer to the boat is often more than 400'. Most of the bigger loads on the boat are 240-volt loads. So, if you start at 208-volts, you are starting with a voltage drop of 13.3% right at the transformer. Yes, most of the loads would work OK at 208, but keeping 208 at the load on the boat makes the copper cost astronomical. Some of the distances are over 700', and that makes the copper cost even harder to digest.

Now, voltage drop on a 120/240 volt circuit when 120-volt loads are used on both phases is less than they would be on a 120/208-volt circuit (when using 120-volt loads on both phases).

There is a reason the code tells you to not feed these boats (that are wired for 120/240) from a 208Y/120 source.

 

If vd is that much of an issue maybe the necessary should be followed for wire size, if the customer is too cheap to buy the correct size wire then maybe they shouldn't begin the project

 

Why spend a ton on copper when it could be done in the xrfrmr? It adds weight to the float with the oversized copper. I would step the voltage up, but I guess Im a cheap sob who would rather solve a problem e easy way. Have you priced type w or type g lately? 24-30 per ft. For 250-4

And the way that the marina loads at calcd are usually way overkill. By overkill I mean 6- 8 125/30a receps on a 100 breaker fed with 250. Most people use the power to charge a battery or run a light. In a commercial or yacht setting it's a whole other ball of wax.

I like the 480/277 to a power distribution xrfrm on the dock then stepped down for branch wiring.


Is there such a thing as a 208v Single phase 50a recep? Most of the yachts have the universal regulators so they can be plugged into whatever voltage source.

 

The wire length from the transformer to the boat is often more than 400'. Most of the bigger loads on the boat are 240-volt loads. So, if you start at 208-volts, you are starting with a voltage drop of 13.3% right at the transformer. Yes, most of the loads would work OK at 208, but keeping 208 at the load on the boat makes the copper cost astronomical. Some of the distances are over 700', and that makes the copper cost even harder to digest.

Now, voltage drop on a 120/240 volt circuit when 120-volt loads are used on both phases is less than they would be on a 120/208-volt circuit (when using 120-volt loads on both phases).

There is a reason the code tells you to not feed these boats (that are wired for 120/240) from a 208Y/120 source.

What code says not to feed boats from 208y. I have worked in rv parks that were horribly set up with 208y and they didn't have huge vd issues

 

What code says not to feed boats from 208y.

Try 555.19(A)(3), read the informational note for clarity.

Now, if you are just feeding 120-V receptacles then a wye service will work fine.

 

Try 555.19(A)(3), read the informational note for clarity.

Now, if you are just feeding 120-V receptacles then a wye service will work fine.

Ill check it out I didn't know that was code

 

hardworkingstiff,
i just flipped thru the 2011 NEC 555.19 A 3
theinformational note states , supplying receps and voltages other than marked on the recep MAY cause overheating or malfunctioning of connected equip im gunna skip the example , to me that dosent prohibit it due to the word "shall" missing , i would say not a problem

if you feel your going to have VD issues with 208y due to the lenght of the runs , and the cost of CU i hate to break it to you , the VD problems will still be there with 240/120 single phase .
i would run with the wye , use the correct size cable and polaris it down at the receps if neccesary

wouldnt you go for about a 5% voltage drop at the receps anyways ?

i have dealt with the small cable thing more than i care to mention , the company i work for had 6 gauge ran to their duplex air compressor with a combined FLA of 45 amps for about 300 feet and wondered why they kept frying motors

 

hardworkingstiff,
i just flipped thru the 2011 NEC 555.19 A 3
theinformational note states , supplying receps and voltages other than marked on the recep MAY cause overheating or malfunctioning of connected equip im gunna skip the example , to me that dosent prohibit it due to the word "shall" missing , i would say not a problem

But, the actual code verbiage before the informational note states: Each single receptacle that supplies shore power to boats shall be supplied from a marine power outlet or panelboard by an individual branch circuit of the voltage class and rating corresponding to the rating of the receptacle.

I'd say that is pretty much a command that is not open to discussion (JMO).

 

So what is your solution single phase 120/240? How big is the load? You don't like the transformer speced by the engineer, and you don't like the 120/208Y. The marinas I have done were speced with a 120/208Y and built to spec. These marinas were quite large with a system of manholes for power and low voltage. There was only one utility transformer for the marina and I don't think the power company would ever allow it to be single phase.
I have also done a lot of service work at several marinas that my boss has service contracts with, and most of the problems are from corroded connections. Some of the boats have 100A pin and sleeve power outlets, and I have never heard it being a problem.
You do bring up a good point though, and there has been an occasion here or there where the owner will say that he has problems here that he does not have in Florida. And then he will say something crazy that his boat is also showing reverse polarity on a single phase 50 amp plug. Try explaining that to a fisherman! Sometimes I will make them happy and switch the breakers with the neighboring pedestal. I really doubt that there is a commercial marina in NJ that has a single phase 120/240v service.

 

Im wiring an international terminal that consists of two large docks as we speak. 120/208...

 

Are you feeding 50-amp 125/250-volt receptacles from the 208Y/120 service (which IMO is a violation of 555.19(A)(3))?

 

The way I see it

Moving beyond the code telling us not to supply these 125/250-volt receptacles from a 208Y/120 source, let me express my other concerns a little more in depth.

Most of these boats are set up to use a single-phase 120/240-volt supply. Most of the conductors lengths are pretty long, so VD will be an issue.

Remember, although most 240-volt loads will operate at 208-volts, resistance loads will have lower output and inductive loads will draw a higher amperage which contributes to more heat generation in the system.

Now, let's say you start at 240-volts and you have an overall VD in the premise wiring of 3% and PoCo of 2% (which during high power consumption in a marina is usually not achieved).

Let's say the power company is operating on a system wide heavy load. This often will lead to a 5% drop in voltage from the PoCo. On the single-phase system, you go from 240-volts to (5% system drop and 5% premise drop) 216-volts. That's a voltage the boats will still operate reasonably well.

Now, on a 3-phase system, you start at 208 and wind up with 187-volts (108 on the 120 side). Most of the 240-volt loads on the boat will really have a hard time operating at 187-volts. The 108-volts for the 120-volt loads will be OK, but those AC units will be very stressed and will have premature failure if operated for a long duration at this voltage level.

The other thing most people don't consider is how VD works on these circuits. On a single-phase service, if you are fully loaded at the boat (50-amp circuit), you have 50-amps on A, 50-amps on B, and 0 on N. On a 3-phase system, you have 50-amps on A, 50-amps on B, and 50-amps on N. You now have 3 CCCs instead of 2 and the VD will be higher on the 3-phase system than the single-phase system under this scenario. I didn't mention though that since the voltage for the 240-volt loads is lower on the 3-phase system, you will actually be trying to pull more than 50-amps on the 3-phase system than you will on the single-phase system for the same power consumption. Amps is heat. IMO, you will have dissatisfied customers and, if they know the NEC, they may have a reasonable law suit (for any damages to their equipment) against the marina (which will turn to the engineer and contractor) for supplying the 125/250-volt receptacle from a 208Y/120-volt source.

I intend to not be in that loop.

Using a 208Y/120 system to service 50-amp 125/250-volt receptacles at a marina is a code violation and just poor engineering. I will try not to respond anymore because I think stated my position well enough.

 

Moving beyond the code telling us not to supply these 125/250-volt receptacles from a 208Y/120 source, let me express my other concerns a little more in depth.

Most of these boats are set up to use a single-phase 120/240-volt supply. Most of the conductors lengths are pretty long, so VD will be an issue.

Remember, although most 240-volt loads will operate at 208-volts, resistance loads will have lower output and inductive loads will draw a higher amperage which contributes to more heat generation in the system.

Now, let's say you start at 240-volts and you have an overall VD in the premise wiring of 3% and PoCo of 2% (which during high power consumption in a marina is usually not achieved).

Let's say the power company is operating on a system wide heavy load. This often will lead to a 5% drop in voltage from the PoCo. On the single-phase system, you go from 240-volts to (5% system drop and 5% premise drop) 216-volts. That's a voltage the boats will still operate reasonably well.

Now, on a 3-phase system, you start at 208 and wind up with 187-volts (108 on the 120 side). Most of the 240-volt loads on the boat will really have a hard time operating at 187-volts. The 108-volts for the 120-volt loads will be OK, but those AC units will be very stressed and will have premature failure if operated for a long duration at this voltage level.

The other thing most people don't consider is how VD works on these circuits. On a single-phase service, if you are fully loaded at the boat (50-amp circuit), you have 50-amps on A, 50-amps on B, and 0 on N. On a 3-phase system, you have 50-amps on A, 50-amps on B, and 50-amps on N. You now have 3 CCCs instead of 2 and the VD will be higher on the 3-phase system than the single-phase system under this scenario. I didn't mention though that since the voltage for the 240-volt loads is lower on the 3-phase system, you will actually be trying to pull more than 50-amps on the 3-phase system than you will on the single-phase system for the same power consumption. Amps is heat. IMO, you will have dissatisfied customers and, if they know the NEC, they may have a reasonable law suit (for any damages to their equipment) against the marina (which will turn to the engineer and contractor) for supplying the 125/250-volt receptacle from a 208Y/120-volt source.

I intend to not be in that loop.

Using a 208Y/120 system to service 50-amp 125/250-volt receptacles at a marina is a code violation and just poor engineering. I will try not to respond anymore because I think stated my position well enough.

You said it, poor engineering. There's got to be a better way around this.

 

I will return. With a good argument of this in a couple hours. Need to ponder it

 

I reread my last post and I noticed a mistake. The scenario of the 3-phase load distribution is not exactly correct (50A on A, 50A on B, and 50A on N). That only holds true if these are 100% 120-volt loads, N would not carry current from 240-volt loads.

My bad.

The rest of the example I believe is correct.

 

I reread my last post and I noticed a mistake. The scenario of the 3-phase load distribution is not exactly correct (50A on A, 50A on B, and 50A on N). That only holds true if these are 100% 120-volt loads, N would not carry current from 240-volt loads.

My bad.

The rest of the example I believe is correct.

The neut will only carry the imbalance of the 120 volt loads

 

Exactly, and it works differently on single-phase and 3-phase. On 3-phase supply with the circuits we are describing, the neutral is counted as a CCC where on the single-phase supply the neutral does not need to be counted as a CCC.

 

A noodle is a noodle as cs would say

 

I have no idea of what that means. I guess I'm just getting too old. :laughing:

 

The handbook also shows a 120/208v twist lock marine grade receptacle on the same page. I would imagine you would have to match the plug with the system and that would be it.

 

Very few boats on the NC coast use that configuration. They are mostly the 50-amp 125/250-volt receptacles or for the smaller boats the 30-amp 120-volt receptacles.

 

Normally we see an open delta system with a few three phase 100 amp outlets strategically placed for when the big boys roll in. Also note that it is sometimes handy to have a delta/delta transformer around if someone requires 3 phase 480.

 

Do you have exposure to marinas? Is that a typical configuration you see down there?

That configuration makes sense so long as the boats don't use the neutral in the 3-phase configuration and from what I understand, most boats that use 3-phase feed a transformer on the boat to deliver the voltage the boat requires. I've heard (since most of these boats cruise the world) these boats have quick change primaries so they can deal with different voltages around the world.

 

We are supplying 1 phase 30a, 1 phase 50a, and 3 phase 50a receps. Ill have to check on the voltage rating of the twist locks. The shore power boxes are being custom made, so maybe I can get them to install 120/208 devices. As for voltage drop our longest run at this point is about 400'. Its specd at #2 for the 50a loads...

 

solutions?

I had to bring this post back up because Im dealing with this issue as we speak. I understand 555.19(A)(3), and Im not disputing the wording. We have a 12470v to 120/208v transformer feeding shore power. We are supposed to provide 30a 120v 1 phase(no problem), 50a 208v 1 phase(problem), and 50a 208v 3 phase(problem). I cant find anything other than 30a 120/208v 1 phase marine twist lock. The others who posted earlier that they have installed shore power systems @ 208v, did you just go ahead and install the 125/250v outlets and call it good? Im meeting with a Hubbel rep next week to see if we can come up with a solution. For now Im just brainstorming so any help or advise would be appreciated.

 

Just remember, the mid sized boats have the male 125/250-volt plugs. Installing a receptacle other than the 125/250-volt for use with these boats probably won't work.

I believe most people just feed the 125/250-volt receptacle with 208/120 without regard to the consequences. I'm so glad to see you taking this seriously. I hope you will share any solutions you come up with.

 

Just remember, the mid sized boats have the male 125/250-volt plugs. Installing a receptacle other than the 125/250-volt for use with these boats probably won't work.

I believe most people just feed the 125/250-volt receptacle with 208/120 without regard to the consequences. I'm so glad to see you taking this seriously. I hope you will share any solutions you come up with.

The vessels we will be supplying will be good sized probably from 80' fishing vessels up to frieghters 100's of feet in length. I cant see them re-engineering the whole project, especially being this far along. We'll see what we can come up with...

 

I have bid on atleast 8 marinas all with similar design issues. If it makes you uncomfortable ask that you be released from any damages that may arise from the enigineers drawings. A 200' freighter sure as hell wont just need a 50a service. Give the guys over at Eaton or Hypower marine a call and get their opinion on the matter

I believe most people just feed the 125/250-volt receptacle with 208/120 without regard to the consequences. I'm so glad to see you taking this seriously. I hope you will share any solutions you come up with.

Electricity is no laughing matter...unless you're a clown

Sounds like mr. hard-stiff helped write the latest edition of the NEC so whatever I say will be argued

Good luck

 

Sounds like mr. hard-stiff helped write the latest edition of the NEC so whatever I say will be argued

Well, no I did not, but I do love to debate (argue)

I am curious though, why is it you think feeding equipment designed to operate on 240-volts is OK being fed with 208-volts?

Most marinas I've seen will in no way be able to maintain a 5% or less VD on the premise wiring during high demand. Most of the PoCo's reserve the right to lower voltage 5% during heavy usage.

So, it would not be uncommon to see an overall 10% VD during heavy usage. So, 240*.9 = 216-volts and 208*.9 = 187-volts. Do you think 240-volt equipment holds up well on 187-volt source?

IMO, if you want to do a half/azz job, feed that 50-amp receptacle with 208-volts (and it is a code violation as we all know). If you want to be one of the better installers, well, you get the picture.

 

I do whatever electrical comes my way. the boat I referenced was a 40' longliner /troller with an ice maker. I think the package was made by MER. The only rule I know for boats is there is none. I mean the figuratively of course

A resistive load is fine to run at the lower voltages it's the inductive ones I care about

Look at all of the apartments out there that are 208

 

I do whatever electrical comes my way. the boat I referenced was a 40' longliner /troller with an ice maker. I think the package was made by MER. The only rule I know for boats is there is none. I mean the figuratively of course

amen

A resistive load is fine to run at the lower voltages it's the inductive ones I care about

Look at all of the apartments out there that are 208

I've not been involved in those, but don't they order equipment rated for 208 instead of 240?

 

Stiff, I too share your concern. During light loading if the connectors are new and shinny VD is low. 208V might turn a 240V motor just fine.

During peak loading, Vd is high, green connectors are green the worse case calculated voltage of 187V will either burn up the connector or the motor loads.

The wording in 555.19 (A) (3) states the "voltage class and rating corresponding to the receptacle rating" because the know a 240V 50A receptacle running a motor load on 208V will pull much more than 50A.

Did the "engineer" seal his drawings? Did you go on-line to see if he is an electrical engineer (working within his discipline)? Did you run this by the AHJ..he won't approve the plan or the installation, if someone doesn't follow the plan.

You're to be congratulated on your concerns.:thumbsup:

 

You're to be congratulated on your concerns.:thumbsup:

Thank you!

 

Thanks for the feedback guys. 220, you said you have bid at least 8 jobs like this; did you win any of the bids and how did you get around the situation. This isnt a marina. The phase we are currently working on is a 400 foot long dock. There are no slips, just one long dock with bumper piles and cleats along the bay side of the dock. Its strictly for commercial use. My comment about freighters tying up there is info from the port, and their goal is to accomidate these vessels. Along the 400' dock there are 3 shore power boxes, and each contains 2 30a 1ph, 2 50a 1 ph, and 2 50a 3ph. The plans show them as pin and sleeve type receps. The plans also have voltage drop calcs, and all of the circuits show about 201v at the pedistal on the prints. I would agree this would probably be the best case scenario, and no I dont think its a good idea to feed 240v loads with 201v.
Thanks again for the feedback, this seems to be an issue that comes up often.