208volt Problem at Marinas

[Seevee]

All,

Just curious, what percentage of you folks are running into the 208v problem at Marinas? Especially in FL and on the Loop.

Seems like a lot of Marinas set up the 208 volt option because it's cheaper, but doesn't have full voltage (208 vs 220, and the 104 vs 120 on the legs). And it could cause an issue with some appliances, especially AC units. Shouldn't hire lights or heating elements. Not sure about the fridge.

There is a solution that one can do is have a transformer boost the power up when encountering the 208, or simply run the generator.

I'm trying to figure out if it's worth the effort with the transformer project depending on how many marinas have this issue?

Thoughts and experiences?

[sunchaser]

208 is commonplace in BC. Seems to work ok for thousands of vessels and millions of homes and businesses.

[The Other Gary]

I design marina docks and there are very good reasons for the installations.
First off your Air Conditioners, if they are newer, are 230 volt 60hz in North Anerica.
The acceptable voltage input is 208 to 240 volts at 60hz. 120 Volt 60 hz units have an acceptable range of 100 to 132 volts 60hz.


208 wye transformers put out 208 and true 120 volts 60hz, not 108 volts as you implied. They can push this for long distances with little or no voltage drop with properly sized wiring.
240 Delta transformers put out 240 and 120 volts but voltages drop with distance quite remarkably, hence the 230 volt rating on the newer Dometic compressors.


On a 600 foot dock a 240 Delta transformer should be installed at the mid point and runs go in 2 directions of 300 feet to avoid line loss. This also requires a huge primary cable out to the transformer, a transformer pad that takes up leasable space and a whole lot of connections in a wet and often salty environment. Floating docks should never use this transformer due to the additional weight and chafe hazards.


A 208 Wye transformer can be installed on shore and deliver 208 volts for 600 feet and true 120 volts even further with proper wire sizing. Some of the cable runs I have done weigh 1200 pounds to service 4 pedestals and take an hour per pedestal just to bend the wires. But they deliver full voltage and have no interim connections near water. This is a huge safety factor.
On my own dock I am slip 7 and have 208 and 122 volts 60hz and my marine electrician and installer is on slip 56 with 208 and 121 volts 60 hz. We can adjust these voltages after installation by using the various taps on a 208 wye transformer.


As your AC units approach the time for replacement you may want to consider replacing each with the new 120 volt units and all your concerns will go away.
Also, if you are experiencing input voltages below what is detailed above it is probably due to an older installation with undersized wiring, perhaps corrosion at the transformers and degraded power tower outlets . Time to talk to your marina about upgrading for safety concerns.


Hope this helps.

[psneeld]

Dont think I have seen anything but around 120 at every marina I have been to from Jersey to Florida...easily over 50 maybe cloiser to 100.

None had power issues....and I usually stay at the more economy minded types.

[Seevee]

The other Gary,

Thx for the heads up.

As for the 120 line getting 120 vs 104 thanks for the head up on that, as I was wondering about that. A very experience ABYC certified electrician told me that. So much for experience.

My AC units will not be affected as they take 208 to 230v.

Don't know about the fridge, but can always run it on 12v. Lights should be an issue. Heaters shouldn't be an issue, stoves, burners, grills. What else is there?

I guess I was curious if this were an issue. Apparently not. Thx.

I always get a second opinion unless I'm totally familiar with things. Amazing how much poor info comes from so called experts.

[The Other Gary]

Your fridge should be 120 volt so no worries there.

[MYTraveler]

My boat's ice maker (not for cocktails, but to fill the fish holds) won't run on 208, which is what my slip provides and is fairly common in California and west coast of Mexico, in my experience. It runs fine on my generator (240 volt), but I prefer to run it for a day ahead of time to have plenty of ice when I depart. It has been suggested that I install a buck transformer (steps 208 volts up to 240) on my dock. Now I just need to find the right transformer at the right price.

[The Other Gary]

Or replace the old compressor on the icemaker with a newer Danfoss type that will run on 208. Whichever is the most cost efficient.


You can also get a Boost and Buck to install on your boat in various sizes that you can dedicate to the icemaker only quite reasonably. This way you only need a single phase B&B in say 20 amp and some are rated for wet conditions. Saves a lot of negotiations with the marina.


1-Phase Buck/Boost Step-Up Transformer - 208V Primary - 240V Secondary - 23.4 Amps - 50/60Hz - Larson Electronics


Note that this is only for a 208 line and uses no neutral so there is no splitting off 120 volts downstream if your icemaker fan motors or other peripherals need 120V.

[diver dave]

Originally Posted by The Other Gary

I design marina docks and there are very good reasons for the installations.
First off your Air Conditioners, if they are newer, are 230 volt 60hz in North Anerica.
The acceptable voltage input is 208 to 240 volts at 60hz. 120 Volt 60 hz units have an acceptable range of 100 to 132 volts 60hz.


208 wye transformers put out 208 and true 120 volts 60hz, not 108 volts as you implied. They can push this for long distances with little or no voltage drop with properly sized wiring.
240 Delta transformers put out 240 and 120 volts but voltages drop with distance quite remarkably, hence the 230 volt rating on the newer Dometic compressors.


On a 600 foot dock a 240 Delta transformer should be installed at the mid point and runs go in 2 directions of 300 feet to avoid line loss. This also requires a huge primary cable out to the transformer, a transformer pad that takes up leasable space and a whole lot of connections in a wet and often salty environment. Floating docks should never use this transformer due to the additional weight and chafe hazards.


A 208 Wye transformer can be installed on shore and deliver 208 volts for 600 feet and true 120 volts even further with proper wire sizing. Some of the cable runs I have done weigh 1200 pounds to service 4 pedestals and take an hour per pedestal just to bend the wires. But they deliver full voltage and have no interim connections near water. This is a huge safety factor.
On my own dock I am slip 7 and have 208 and 122 volts 60hz and my marine electrician and installer is on slip 56 with 208 and 121 volts 60 hz. We can adjust these voltages after installation by using the various taps on a 208 wye transformer.


As your AC units approach the time for replacement you may want to consider replacing each with the new 120 volt units and all your concerns will go away.
Also, if you are experiencing input voltages below what is detailed above it is probably due to an older installation with undersized wiring, perhaps corrosion at the transformers and degraded power tower outlets . Time to talk to your marina about upgrading for safety concerns.


Hope this helps.

Thanks, I learned something from this, and i'm in the electrical industry.
I don't design 3ph systems however. Can I ask this? If you are taking 120V from a delta winding, that would be a grounded center tap side, correct? And, then, only one phase can then be used for 120V correct? As opposed to a Y config, where each phase to earth/neutral is 120V? Is that the basis of the greater voltage drop situation? due to phase imbalance?

[The Other Gary]

A 208 Wye Transformer can deliver 120V from all three phases. We alternate each set of power towers red black white, blue black white and blue red white for load balancing and to supply phased 208V to every tower on every 3 phase breaker.


I only design floating docks so a 240 Delta is a non starter so we only design in 208 wye.

[twistedtree]

If your boat takes 208-240V dock power into an isolation transformer, and creates it's own 120/240 split phase on board, then 208V coming in will end up as 104V per leg on board. That's how 208V dock power tuns into unacceptably load "120" voltage on your boat. My boat is set up this was, as are money Nordhavns. So your ABYC guy was right, at least in this context.

[Aft Deck Capt]

"208 wye transformers put out 208 and true 120 volts 60hz, not 108 volts as you implied. They can push this for long distances with little or no voltage drop with properly sized wiring.
240 Delta transformers put out 240 and 120 volts but voltages drop with distance quite remarkably"

This Needs To Be Clarified! If the load, wire size and distance are the same then the voltage drop will be the same regardless of the type of transformer! The physical configuration of a Delta XFMR does not lend itself to balancing 120V loads like a Wye XFMR. Utilizing a Delta XFMR with 120V being the intended load is very inefficient as the 120V is only derived via one split winding, leaving the other two unused.

[diver dave]

Originally Posted by Aft Deck Capt

"208 wye transformers put out 208 and true 120 volts 60hz, not 108 volts as you implied. They can push this for long distances with little or no voltage drop with properly sized wiring.
240 Delta transformers put out 240 and 120 volts but voltages drop with distance quite remarkably"

This Needs To Be Clarified! If the load, wire size and distance are the same then the voltage drop will be the same regardless of the type of transformer! The physical configuration of a Delta XFMR does not lend itself to balancing 120V loads like a Wye XFMR. Utilizing a Delta XFMR with 120V being the intended load is very inefficient as the 120V is only derived via one split winding, leaving the other two unused.

I think the comment on higher wire losses applies to the primary feed, not the 240/120 feed. Why? because delta transformers suck at non-3 ph loads. I suspect even the larger issue is the waste of transformer capacity providing essentially only single phase loads with a transformer designed for 3 ph.

If you dive one step deeper and ask why a delta can only draw from two phase primary legs to feed a 240/120V load, you will find out that the primary wiring is only 3 current carrying conductors, as opposed to 4 with the Y. So, making 240/120 requires you to center tap one winding and ground it. You can only do this to one side, so you loose the other two sides to provide any neutral referenced 240/120 loads.

So, if your intent is to drive industrial 3 phase loads, the delta can save a wire at the primary. If your intent is to drive a marina, where no body has 3 phase loads, but the supply is 3 ph. the Y is much better.
The other consideration is the 3 phase voltage available. As mentioned in previous posts, the Y doesn't get you 240V, it gets you 208V. The delta will get you true split 240/120 , just like the house.

This brings up another question for the other Gary. Why not run the marina primary feeds and transformers more like a residential system? That is, why have 3 ph transformers at all on the docks? Why not 600V (or whatever) 1 ph running to single phase 240/120 grounded neutral transformers on the dock? You can still use a primary 11kV (or whatever) 3 ph distribution transformer land side, and the 3 wire 600V secondary can feed 3 sections of dockage?

[The Other Gary]

Geez Guys, You are getting way beyond my pay grade. I rely on the master electrician to spec the installations for the docks I design. I always ask why this and why that so I can deliver the best value to the end user with a minimum of complaints about less than adequate power for his customers and the master electrician has to justify his choices to the power authority inspectors who focus on BOTH quality and safety.
Most of Canada is 3 phase for new installations and always for floating docks with transformers mounted on shore.

[Seevee]

Originally Posted by diver dave

-----------------------



This brings up another question for the other Gary. Why not run the marina primary feeds and transformers more like a residential system? That is, why have 3 ph transformers at all on the docks? Why not 600V (or whatever) 1 ph running to single phase 240/120 grounded neutral transformers on the dock? You can still use a primary 11kV (or whatever) 3 ph distribution transformer land side, and the 3 wire 600V secondary can feed 3 sections of dockage?

Diver Dave,

Good question.

I'm still trying to get my head around this stuff, and easy to get confused. I'm still not sure why the 3 phase Wye is better.

But more important is what to do about it, if anything, as a boater.

[diver dave]

http://www.programmablepower.com/sup...stribution.pdf

fig 2 is a house.
fig 4 is the dock layout with Y

fig 10 is the delta with 240/120. Of note, phase C supplies zero of the load (therefore a lack of balance/efficiency)

[diver dave]

Originally Posted by The Other Gary

Geez Guys, You are getting way beyond my pay grade. I rely on the master electrician to spec the installations for the docks I design. I always ask why this and why that so I can deliver the best value to the end user with a minimum of complaints about less than adequate power for his customers and the master electrician has to justify his choices to the power authority inspectors who focus on BOTH quality and safety.
Most of Canada is 3 phase for new installations and always for floating docks with transformers mounted on shore.

So, the first question to ask is: are there any 3 phase consumers on the dock? If the answer is no, then Q2 is : why the he## are we specing in 3 ph transformers ON THE DOCK? Obviously, most marinas are supplied 3 ph from the pole, but that doesn't necessarily translate the need to 3 ph on the docks.

Q for the crowd: how big does a yacht need to be to require 3 phase power?

canada; I just returned yesterday from a job in newfoundland. Working with Hydro LN on a 230kV substation job in the middle of nowhere. Great bunch of guys out there!

[Seevee]

Diver Dave,

That's the same question I'd ask. (and good paper of wiring diagrams).

Seems like the common "house" wiring would be better for a marina, all single phase. And don't understand why Wye is better. Same wires, less power. What am I missing?

Also, I still can figure out where the 208 comes from.
If you have 120 from neutral to Phase A,
and 120 from neutral to Phase B,
Then why wouldn't you have 240 from Phase A to Phase B?

[Larry M]

This came from Wikipedia.

Three-phase as compared to a single-phase AC power supply that uses two conductors (phase and neutral), a three-phase supply with no neutral and the same phase-to-ground voltage and current capacity per phase can transmit three times as much power using just 1.5 times as many wires (i.e., three instead of two). Thus, the ratio of capacity to conductor material is doubled. The same ratio of capacity to conductor material can also be attained with a center-grounded single-phase system.

Three-phase systems may also have a fourth wire, particularly in low-voltage distribution. This is the neutral wire. The neutral allows three separate single-phase supplies to be provided at a constant voltage and is commonly used for supplying groups of domestic properties which are each single-phase loads.

[twistedtree]

Originally Posted by diver dave

So, the first question to ask is: are there any 3 phase consumers on the dock? If the answer is no, then Q2 is : why the he## are we specing in 3 ph transformers ON THE DOCK? Obviously, most marinas are supplied 3 ph from the pole, but that doesn't necessarily translate the need to 3 ph on the docks.

Q for the crowd: how big does a yacht need to be to require 3 phase power?

canada; I just returned yesterday from a job in newfoundland. Working with Hydro LN on a 230kV substation job in the middle of nowhere. Great bunch of guys out there!

It's economics. With a 3 phase transformer on shore or out on the docks somewhere, the output is three 208/120V circuits. That will service more slips at a lower cost.

As people have noted, most "240V" appliances are just fine with 208V. It's at the low end of the allowed range, but OK.

The problem is when a boat has an isolation transformer and creates their own "120V" from the 208V rather than directly using the two legs of the incoming 208/120. That's how you end up with 104V on your boat, and start having trouble with appliances. Add heavy loads a voltage drops out at the end of the docks, and you can end up in the 90s somewhere.

Good isolation transformers (actually all that I know of) have a step-up capability that will take 208V in and make 240/120V out. But very few people wire to take advantage of it. Specifically at my request, our boat has switch selection positions for "Shore Normal" and "Shore Boost" that configures the transformer for 1:1 or a step up from 208 to 240.

Charles used to offer an IsoBoost isolation transformer that would detect the incoming voltage and do the step up automatically, but I don't believe they make it any more. But their other isolation transformers all can be wired like mine with a normal and boost configuration.

If you are considering an external boost transformer, it would be worth at least evaluating whether it could be installed inside the boat to give you isolation as well as boost capability. Space and existing wiring will be factors, but if you can pull it off, I think it gives the best results.