Low voltage from 120 side

[ageless]

One AC unit is 120, the other (3) 220. The 120v unit is only getting 107 volts, as are the outlets throughout the vessel. Where do I even start trying to figure this out? I really feel like this is beyond my ability, any recommendations who’d be qualified to diagnose?

 

[Tricia II]

Most likely a bad receptacle or plug to the boat, or a bad connection somewhere in the circuit that has low voltage, like where the cable connects to the plug or receptacle on the boat side. It could also be bad connection on the breaker dockside.
Your best bet is to start at the line side of the breaker then the load side and work down to the power panel from there.

 

[madhatter1]

Are you plugged into 240 or 208?

 

[Pascal]

Start at the source and measure voltage at the pedestal. On a 120/240-50 you should find 120 between each leg and the neutral as well as 240 across the hots.

There could resistance in one of the shore power cord connection causing voltage drop under load

 

[Captain Ralph]

This is dock power and/or gen-set?
If dock power, Do you have a transformer?

 

[Tricia II]

If it doesn't have the issue on Generator, it is a dock power issue or a power cable issue between the dock and the boats power panel.
That should be an east test.

 

[madhatter1]

An 88 boat will have transformer. 208 (approximately, never exact) will poop out 104 volts rather than 120 240 would poop out. Unless modified with a boost switch that swaps taps to account for lower shore power voltage. This is Sky's area of expertise on the boost switch. But transformer windings are simple math.

I deal with this all the time with stats on AC units. The BMS stats we install need good voltage or they won't power up. Previous battery stat worked fine and would run the unit. But ours has too low a voltage to power up. Why? Because the AC units 24 V transformers will always come tapped for the highest voltage they will see. 240V. Power it with 208 which is typical on a commercial site and the normal 27-28V output is now about 23.5 volts with zero load on it.

My guess is incoming shore power voltage is around 214 volts. If this is a resistance/bad connection issue it must be solved ASAP. Potential fire issue.

 

[SKYCHENEY]

With the transformer, if you feed it 3-phase 208v, which is 120 degrees out of phase, it will output 208v single phase that is 180 degrees out of phase. This gives you 104v between each leg and neutral or ground instead of the 120v that you would normally get with 208.

SO the question is, what is the input voltage to the transformer?

 

[ageless]

The voltage remains 107/108 on the gen. I recently installed new light switch’s/outlets and GFCI outlets and will be checking all those connections. Interesting finding…ONLY IN THE MASTER HEAD, the GFCI won’t “trip” but it resets, 2 NEW receptacles tested.

 

[ageless]

I have checked all the connections to the new outlets and switch's, found a loose ground on a GFCI, this correction didn't change anything, voltage today is reading 102.6 on shore power.

Riddle me this......rear salon lights are on a 3 way switch. I forgot this when ordering switch's so I'm still searching for a matching 3 way. That being said, one side has an "open" jumper wire, could this cause the voltage drop?

I had a revelation today, do you think my lack of hot water is coming from voltage too low? Gave that a little check, sure enough 207 volts.

 

[madhatter1]

You need to meter the power on the shore connection first. If low it has nothing to do with your boat or cord. Sure probably some stuff worth fixing on your boat but if chasing down voltage issues no matter what you need to start at the source. If that is good then the cord, connection at the boat, connections within the boat.

 

[Pascal]

Let me repeat what I said earlier :

Start at the source and measure voltage at the pedestal. On a 120/240-50 you should find 120 between each leg and the neutral as well as 240 across the hots.

There could resistance in one of the shore power cord connection causing voltage drop under load

What are you showing on the panel voltmeters?

Now are you saying that on generator you are also only getting 108 volts?

A poorly connected new outlet or light switch isn’t going to affect voltage on other circuits

 

[ageless]

I have not checked voltage on the tower due to the fact the low voltage remains when running off the gen. We are headed north today to Satellite beach area so I’ll have a new power source to contend with, I’m not confident anything will change. The ONLY changes to the vessel since this started is the new outlets/switch’s and Oceanbreeze HVAC units installed.

 

[ageless]

Another interesting finding while trying to diagnose no heat in the salon. Controls read that unit is getting 239v, how could it have the necessary voltage but the hot water heater doesn’t?

 

[Pascal]

Well that’s why to need to get a multilmeter and check voltages. Check voltage at the breakers for the new air con, water heater as well as the power source selector for gen and shore.

And again what does the meters on the panel show as voltage?

Without knowing what voltage is coming to the panel it s impossible to know what the problem is

Water heaters are pretty tolerant of low voltage.

 

[ageless]

Well that’s why to need to get a multilmeter and check voltages. Check voltage at the breakers for the new air con, water heater as well as the power source selector for gen and shore. And again what does the meters on the panel show as voltage? Without knowing what voltage is coming to the panel it s impossible to know what the problem is Water heaters are pretty tolerant of low voltage.

200v @ 58 hertz at the panel while on gen, same it’s always been

 

[Pascal]

200v @ 58 hertz at the panel while on gen, same it’s always been

Under load or no load ? Then your gen has a problem. What is the frequency under load? No load you should be around 61hz to make up for slightly lower rpm under load. Freq is directly controlled by RPM. The lower voltage is likely to be your voltage regulator. Some are adjustable. You should be reading 240v

 

[ageless]

Under load or no load ? Then your gen has a problem. What is the frequency under load? No load you should be around 61hz to make up for slightly lower rpm under load. Freq is directly controlled by RPM. The lower voltage is likely to be your voltage regulator. Some are adjustable. You should be reading 240v

That was under light load, same reading of 200v on shore power with same load. I’ve got the “ohno” manual out and will be making adjustments accordingly. I will update with todays voltage readings on the new tower

 

[Pascal]

That was under light load, same reading of 200v on shore power with same load. I’ve got the “ohno” manual out and will be making adjustments accordingly. I will update with todays voltage readings on the new tower

Light load you should have 240 v and 61 hz

 

[Captain Ralph]

What are you using to measure the voltage? Just the panel meters?