Not enough shore power.

DougLas

Well-Known Member
Dec 13, 2008
874
Lake Erie
Boat Info
39 Express
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Just a reminder. Make sure the shore power is giving the boat enough power to operate all of the units needing to power off of it. Why this is being said, some of the marinas are not up to date with power supply needed for boats demand. The marina my boat is in only has one 30amp power supply. So a splitter has to be used to power the boat.
That being said. When using a splitter keep a close watch on the reading on the power panel in the boat. The power with all the boats using it at the dock can go below 110.
Point here is run as little as possible when this reading of below 110 shows up. Hot water heater is one unit to shut off. If there are 2 ac units try to get by with just one.
Reason for this information there are a above normal amount of ac units being replaced in the marina my boat is at now. Even ones that were only within two years old are being replaced.
Just a friendly reminder hope this helps some of the boaters out there.
 
Hmm...I don't think going over on amps and dropping volts are related? Plugging 60 amps of items into a 30 amp pedestal obviously has it's limitations. But 110 should be 110...
 
I popped the breaker on the pedestal in Leland, Mi 2 weeks ago and had to turn off 1 AC.
 
Last edited:
I popped the breaker on the pedestal in Charloevoix, Mi 2 weeks ago and had to turn off 1 AC.
Wow, that's really surprising. Charloevoix has relatively new power runs. Guess we can have voltage drops almost anywhere at times.
 
The 55 with E plex will turn our ACs off when the voltage gets to low. Our 240 is around 208 to 212 when everyone is at the dock using juice.Been arguing with them about the problem but they don't understand what low voltage can do to a boat.More slips, Bigger boats same supply, It's a problem for sure.
 
Hmm...I don't think going over on amps and dropping volts are related? Plugging 60 amps of items into a 30 amp pedestal obviously has it's limitations. But 110 should be 110...

Not so. The problem with the older wiring on the docks. There is not enough back up voltage to help power the amount of units running off the circuit. The only way to solve the problem is to have more voltage available to the units. This being the case a pad mount transformer can help to over come the demand. Although now there is the problem of old wiring at the docks. Will it be able to with stand the added power? Also if the power is real good it can show up to 114. at the control panel.
 
We really only have one marina that we frequent annually where it becomes an issue... https://www.portsidney.com It's in British Columbia and the transformers are 208v and as soon as there's a load on them it's right around 200v depending on where you located... 199v is a code and my A/C shuts down.
 
Hmm...I don't think going over on amps and dropping volts are related? Plugging 60 amps of items into a 30 amp pedestal obviously has it's limitations. But 110 should be 110...
Watts = Current X Voltage If one goes down, the other goes up (to a point) to satisfy the load. Now, let's bring in resistance.
 
208v is actually commercial power. We have a few places with this and carry a buc transformer.
 
North America electrical standards for homes and small buildings is 240v single phase.
The standard for commercial power is based on 3 phase Delta wiring which is 208v across any phase.
Both provide approx 110-115v from hot to neutral.

Most marinas, being commercial operations, will have 208v 3 phase power as their source.

All North America appliances rated 240v will operate at 208v; but somewhat less efficiently.
Motor loads in particular will draw more current while producing slightly less horse power (less torque).
This causes HVAC compressors to have a tough time if rated 240, operated on 208.
And less "margin of error" if the controls are looking for 240v, then 208v is already in the brown out range.
This is where the Buck Up transformer helps pushes the 208v up to a full 240v on the output.

But if they are 110-115v HVAC units this makes no difference at all to the HVAC.
Most our boats have a single or dual 30A 115v inlets. So the above is not the issue.

@370Dancer pointed out the problem, resistance.
There has to be enough copper (or aluminum) to carry a given load, a given distance, without voltage drop.
You can draw the full 30A and not trip the pedestal breaker but suffer voltage drop if your the guy at the end of the pier.

Remember breakers protect the wiring AFTER the breaker, down stream. The 30A pedestal is to protect the shore cable and the boat attached from exceeding 30A. Each pedestal is not typically going to have a dedicated 30A supply. Depending on how any given marina got wired and how much they were willing to spend on copper you may have 2:1, 3:1, 4:1 pedestal outlets to source breakers which may be a 60A or might be a 120A. The supply depends on how big the wire down the docks is.
 
North America electrical standards for homes and small buildings is 240v single phase.
The standard for commercial power is based on 3 phase Delta wiring which is 208v across any phase.
Both provide approx 110-115v from hot to neutral.

Most marinas, being commercial operations, will have 208v 3 phase power as their source.

All North America appliances rated 240v will operate at 208v; but somewhat less efficiently.
Motor loads in particular will draw more current while producing slightly less horse power (less torque).
This causes HVAC compressors to have a tough time if rated 240, operated on 208.
And less "margin of error" if the controls are looking for 240v, then 208v is already in the brown out range.
This is where the Buck Up transformer helps pushes the 208v up to a full 240v on the output.

But if they are 110-115v HVAC units this makes no difference at all to the HVAC.
Most our boats have a single or dual 30A 115v inlets. So the above is not the issue.

@370Dancer pointed out the problem, resistance.
There has to be enough copper (or aluminum) to carry a given load, a given distance, without voltage drop.
You can draw the full 30A and not trip the pedestal breaker but suffer voltage drop if your the guy at the end of the pier.

Remember breakers protect the wiring AFTER the breaker, down stream. The 30A pedestal is to protect the shore cable and the boat attached from exceeding 30A. Each pedestal is not typically going to have a dedicated 30A supply. Depending on how any given marina got wired and how much they were willing to spend on copper you may have 2:1, 3:1, 4:1 pedestal outlets to source breakers which may be a 60A or might be a 120A. The supply depends on how big the wire down the docks is.

That is good way to explain the problem that can exist. One more point is the amount of power it takes to activate an ac system in the initial start up phase.
 
That's why they have start up capacitors.

Start capacitors are there to help shift the phase for the starting winding. They are not there to provide additional power.

The starter winding is energized until the motor spins up to speed, then a centrifugal switch opens up, which interrupts the starting winding.

When your start cap goes, the motor hums, because there is no shift in magnetic field to help start the motor spinning in the proper direction.

A more thorough explanation:
https://en.m.wikipedia.org/wiki/Motor_capacitor
 
Start capacitors are there to help shift the phase for the starting winding. They are not there to provide additional power.

The starter winding is energized until the motor spins up to speed, then a centrifugal switch opens up, which interrupts the starting winding.

When your start cap goes, the motor hums, because there is no shift in magnetic field to help start the motor spinning in the proper direction.

A more thorough explanation:
https://en.m.wikipedia.org/wiki/Motor_capacitor

Thanks for the clarification. Old auto stuff on the brain disease.

shopping

Only an input and a ground here.
 
Start capacitors are there to help shift the phase for the starting winding. They are not there to provide additional power.

I have been told, but not tested for their storage capacity of electricity... Kinda like a battery?

The starter winding is energized until the motor spins up to speed, then a centrifugal switch opens up, which interrupts the starting winding.

When your start cap goes, the motor hums, because there is no shift in magnetic field to help start the motor spinning in the proper direction.

A more thorough explanation:
https://en.m.wikipedia.org/wiki/Motor_capacitor
 
I have been told, but not tested for their storage capacity of electricity... Kinda like a battery?

Capacitors can and do store DC energy, performing like a battery with a + and - terminals. They are exceptional at storing and providing energy very quickly, but not in large quantities. You will typically see large capacitors as part of a DC power supply circuit where they help filter out ripples in the supply voltage (picking up and absorbing the spikes, and providing energy during drop outs/sags). If your into car (or boat) audio, large capacitors can improve your amplifier performance. As the bass kicks in - those amplifiers need a lot of energy quickly. Old school lead acid batteries have a hard time meeting that type of instant demand effectively. The addition of a capacitor (1farad) improves the audio system -- as it allows the capacitor to provide that instantaneous power to the amplifiers, while the lead acid battery provides the constant overall power (and recharges/refills the capacitor).

Capacitors are also used in time delay circuits. The capacitor is like an energy bucket, and it takes x-time to fill that bucket. By varying other elements (size of capacitor, inline resistor to slow the fill rate), one can build a time delay circuit. With an AC motor that works on magnetic fields -- the capacitor is used to delay the building of that magnetic field. The primary winding of the motor builds its magnetic field instantly. The start winding, with the inline capacitor builds it magnetic field microseconds later (time delay). These two fields, built in close time succession (with their physical axis shifted due to winding placement) provide the initial 'magnetic movement' which starts to turn the motor. Once the motor spins, the normal 60hz cycle of the 120v AC power line keep it moving.

A bit dry, but it covers how the start capacitor is used on an AC motor:

Reference link showing large car audio capacitors:
https://www.amazon.com/1-farad-capacitor/s?k=1+farad+capacitor
 
Capacitors can and do store DC energy, performing like a battery with a + and - terminals. They are exceptional at storing and providing energy very quickly, but not in large quantities. You will typically see large capacitors as part of a DC power supply circuit where they help filter out ripples in the supply voltage (picking up and absorbing the spikes, and providing energy during drop outs/sags). If your into car (or boat) audio, large capacitors can improve your amplifier performance. As the bass kicks in - those amplifiers need a lot of energy quickly. Old school lead acid batteries have a hard time meeting that type of instant demand effectively. The addition of a capacitor (1farad) improves the audio system -- as it allows the capacitor to provide that instantaneous power to the amplifiers, while the lead acid battery provides the constant overall power (and recharges/refills the capacitor).

Capacitors are also used in time delay circuits. The capacitor is like an energy bucket, and it takes x-time to fill that bucket. By varying other elements (size of capacitor, inline resistor to slow the fill rate), one can build a time delay circuit. With an AC motor that works on magnetic fields -- the capacitor is used to delay the building of that magnetic field. The primary winding of the motor builds its magnetic field instantly. The start winding, with the inline capacitor builds it magnetic field microseconds later (time delay). These two fields, built in close time succession (with their physical axis shifted due to winding placement) provide the initial 'magnetic movement' which starts to turn the motor. Once the motor spins, the normal 60hz cycle of the 120v AC power line keep it moving.

A bit dry, but it covers how the start capacitor is used on an AC motor:

Reference link showing large car audio capacitors:
https://www.amazon.com/1-farad-capacitor/s?k=1+farad+capacitor
Glad to see more in depth explanation. I stayed on the lighter side to get the point across.
 

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