Low Shore Power Voltage Issue.

[Midnightsun]

OK, so our toaster and small oven seem to be heating poorly. Checked voltage at the plugs and see only 101 volts. Checked voltage at both shore power outlets on the pedestal and get 117 on both of them. Fired up the generator and get 117 volts at the outlets on the boat which is what I should be seeing. My shore power comes in via dual 30amp feed lines into a reverse Y adapter, 50a cord and into an isolation transformer which outputs the power to 2 individual 120volt circuits labeled shore power 1 & 2.

Measured voltage at the wires exiting my shore power inlet, 118.9 on both red and black legs to neutral. Measured between both red and black hots and get only 205 volts. Hmmmm.

Theory, they are using a 208v transformer to get dual phases which leave me under powered? Make sense? I do need probably at least 240v into the isolation transformer I believe in order to get proper single phase power on both legs. Any electrical experts out there?

Everything works fine on board with exception to heating elements which are weak. Has probably been this way forever but last week when we had a hard time making toast I investigated a little more to see why.

My shore power panels shows 215volts however not to sure how accurate that is.

Any advice is much appreciated.

[bud37]

Check across the hots from two separate shore pedestals and see what you get there and a few more....that may tell the story of the shore side wiring back to their breaker panel.

[km1125]

Yea, it sounds like your pedestal if fed from a three-phase feed (not unusual) so you're only getting 208-ish on the "240" side.

Look at the specs for your isolation transformer. You may have alternate taps on either the primary or secondary side that would allow you to raise or lower the voltage a little bit.

[Helmsman]

Had this same discussion with someone the other day. You are on the money with the 208V. Some isolation transformers automatically adjust, some you can manually adjust, and others you can’t.

[Midnightsun]

Unfortunately my Transformer does not have the boost feature. Oh my, 235lbs!! Looked up to see the cost of a boosted one, Oh My!! $8,000 US but the weight has dropped to 135lbs. Any other options out there?

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[Helmsman]

Source of the post Unfortunately my Transformer does not have the boost feature. Oh my, 235lbs!! Looked up to see the cost of a boosted one, Oh My!! $8,000 US but the weight has dropped to 135lbs. Any other options out there?

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Charles is out of the marine business from what I understand. There is a type of isolation transformer called a Bridgeport. They sell marine isolation transformers. I don’t know if they do boosting. There is a contact section on their web site. They responded to me within 24 hours. For a 50 amp 240 volt it would take two of their “pucks” to get 12kw output. The price quoted to me was $2,532 and the two units are about 300 lbs total. You may want to send the question to them.

[Helmsman]

A caveat to the above comments on Bridgeport. This is from someone who knows his stuff. I don’t think he would mind me posting his comments from another forum here. Be aware that these isolation transformers are on boats today, and people report they are happy with them. Some of the below would be mitigated with a proper install.

“At this time, the Bridgeport Magnetics "pucks" DO NOT comply with ABYC requirements for "isolation transformers." The ABYC Electrical PTC and I have been working with the engineers at Bridgeport Magnetics, and I rather suspect that by the 2024 issue of the E-11 Standard, the standard will be revised to accommodate these toroidal pucks. But at that, they will need some engineering assembly/construction/manufacturing changes to do so; so, what is out there today is likely to be obsoleted. Today, they just have loose individual wires emerging from the potting with no strain relief. That will have to change. Furthermore, their design make them highly subject to being installed incorrectly, in places where miscellaneous stored items can be piled on top of them, retaining the heat they produce, and creating fire risk. These toroidal transformers are lighter and smaller than todays isolation transformers, but there are manufacturing concerns with their safety. They clearly have a future in the marine market, but not in their current form factor and packaging.”

[Midnightsun]

Yesterday we plugged into another marina for a few hours, 98v is what I got there. Now we are on the hook and yesterday ran the generator for a short period doing supper, 118v. Definitely a transformer 208v issue we see happening here. First outing on the lithium bank, tons of juice left this morning, to be continued.

Contacted the manufacturer of this unit yesterday and had a discussion. Looks like a solid product and was actually designed to be a drop in product for a similar Charles unit. Not going to do this this season however I will probably get the old transformer out after haul out and start price shopping this winter. Looks to be in the $6500 range.

https://aseapower.com/product/dock-boost-transformer/

[km1125]

Do you really want to do a ~$6500 change to your system to deal with just some docks that deliver the undervolt condition?

Might be easier/cheaper/better to just get a 208-240 transformer and plug between the dock and the boat. You could probably get one for less than $1K and it would always be an asset you could resell when no longer needed.

Just another option.

[bud37]

Seems to me this low voltage at marina thing is fairly common, can be worse depending on where you are in the marina and the age and length of their cable runs, connections etc. as well. That is why I suggested to double check going back up the dock....we had the same issues depending on where your slip was in the run and who was running what.

Hans....does Victron have anything that could help you.....I do like their stuff.....the weight is serious.......mounting would need consideration for sure.........geez my days of moving things like that around are long over...