Shut down shore power during storms?

jhance · Nov 27, 2017

The thought crossed this brain that I don't want to risk potentially damaging anything electrical in the boat with brown- or black-outs. I've been shutting off AC shore power as a result in high winds as we do get power outages in our area (San Juans).

Is this generally a good practice or something that you all do as well? As long as my bilge pumps are hard wired to batteries, which they are, I see no reason why not. When storm passes I turn AC power back on to run low-watt heaters and a fan.

LaBomba · Nov 27, 2017

I would consider and have shut off power during lightning storms, for fear of surges, but I do not understand your reasoning for shutting it off during high winds. If the power goes out it goes out and it should not harm anything. Just my opinion FWIW.

jhance · Nov 27, 2017

Yes but what about a brown-out where voltage dips and surges wildly.... as in... lights go dim for several seconds. I'm thinking I don't want that going into my inverter/charger, heater/fan, fan, etc.

Plus a black-out, at least in our area, is rarely just a hard shut-off of power. Usually there is some form of brown-out just before.

FF · Nov 28, 2017

Box stores have surge protectors for about $75 that will should care of surge from a nearby lightning strike for house current.

How the DC electronics and computer engine injection setup handles surges is always a problem.

Pgitug · Nov 28, 2017

LaBomba said:
I would consider and have shut off power during lightning storms, for fear of surges, but I do not understand your reasoning for shutting it off during high winds. If the power goes out it goes out and it should not harm anything. Just my opinion FWIW.

Shutting down power during lightning storms is a good idea, but unless you physically unplug your shore power cord you are not protected. The damaging lighting “spike” can, and usually does, enter your boat via the ground wire which is still connected when the power breaker is turned off!

aboatman · Nov 28, 2017

If you are not on your boat at the time of the storm, you can't really do that. That would be about 99% of the time for most of us. And as suggested by Pgitug, you gave to physically unplug the cord to get any real protection.

A lightning strike will take out your appliances regardless.

Unplug it if you can and want to, but for most of us it's impractical and a low risk.

boathealer · Nov 28, 2017

FF said:
Box stores have surge protectors for about $75 that will should care of surge from a nearby lightning strike for house current.

How the DC electronics and computer engine injection setup handles surges is always a problem.

If you've got 100's of Ah of batteries connected, the DC side of the system is not an issue with regards to surges our brownouts. The battery bank is a BFC.

OldDan1943 · Nov 28, 2017

I have boat insurance to cover this. If I time it right, I can upgrade the electronics and installed professionally too.

Of course when you have a storm at home, you unplug your TV then go open the breaker at the house feed then, light the candles, qnd start a fire in the wood stove or sit in the dark.
(innocent look)

sunchaser · Nov 28, 2017

JH
Thousands of vessels in the PNW remain plugged in all the time. Certainly mine is. Never had an issue in the 12 years we've been at same marina.

What do your marina owners recommend? Does the marina have a unique issue?

jhance · Nov 28, 2017

sunchaser said:
JH
Thousands of vessels in the PNW remain plugged in all the time. Certainly mine is. Never had an issue in the 12 years we've been at same marina.

What do your marina owners recommend? Does the marina have a unique issue?

Haven't received a clear answer from harbormaster on this issue. I just know i dont want power fluctuations coming i to my boat via brown outs or power surges, period. Not worth it in my opinion especially since I'm not a liveaboard. power went out again last night (likely associated with some form of brown out just prior) so I'm happy that I shut off shore power. I've had other equipment, not on boats, get fried due to brown outs, so I'm naturally cautious on this front. Curious to hear none of you implement this practice.

sunchaser · Nov 28, 2017

jhance said:
Curious to hear none of you implement this practice.

When I'm not on vessel for an extended period, the only power draws are for heaters and chargers. What do you leave on? I'm not too concerned about "low" voltage for either of these items.

But brown outs? Not an issue at my marina that I'm aware of. Sounds like your docks have some problems.

jhance · Nov 28, 2017

sunchaser said:
When I'm not on vessel for an extended period, the only power draws are for heaters and chargers. What do you leave on? I'm not too concerned about "low" voltage for either of these items.

But brown outs? Not an issue at my marina that I'm aware of. Sounds like your docks have some problems.

I have on my AC main, battery charger/inverter, and AC receptacles powering a fan and two low-watt heater/fan units.

The issue isn't necessarily at my marina. My common sense tells me to minimize allowing highly-fluctuating voltage into ANYTHING electrical - boats, at home, etc. I've seen motors and electrical gizmos have big issues in those situations. I figure there's no point to risk it and no harm done in shutting off shore power before an approaching storm that will likely result in one or many electrical anomalies. Good to hear many of you don't have issues... maybe this is more of an "island" worry!

aboatman · Nov 29, 2017

If you have a refrigerator and use it, you'll probably want to stay connected to shore power. If it switches to battery power, you'll get three or four days max, depending on your batteries and ambient temperature.

OldDan1943 · Nov 29, 2017

Sent my boat to the yard for a week. (no shore power) I have a 12v fridge, full of food. I have two solar panels on the pilot house roof, charging the batteries. When I got back to the boat, all was well.

Shrew · Nov 29, 2017

I'd be far more worried about a low watt heater running unattended than about the potential issues with a power surge or brown out. I've witnessed these devices start a fire. Is your boat in the water? Why are you running a heater at all?

How many devices have you needed to replace at home as a result of these conditions?

jhance · Nov 29, 2017

Shrew said:
I'd be far more worried about a low watt heater running unattended than about the potential issues with a power surge or brown out. I've witnessed these devices start a fire. Is your boat in the water? Why are you running a heater at all?

How many devices have you needed to replace at home as a result of these conditions?

I'm running two west marine "dehumidifier" but they are really a low watt heater with fan. I think most people run similar devices on their boats to help keep temp up and air moving to prevent against mold and freezing temps. yes boat is in water. I'll get mold if I do nothing.

I've had fried computers and a washer fry from brown outs.

CaptTom · Nov 30, 2017

I think we may be missing the definition of "brown out." To me, that means a sustained low-voltage situation introduced by the power company during times of critical demand on the grid.

In that case, motors like fans and compressors might be working a little harder. But presumably voltage is not lowered enough to damage them in normal use.

So let's move on to voltage surges (spikes) and sags. I live at what used to be the far end of a 15-mile-long line from the nearest substation, along a tree-lined, winding road. Suffice it to say I know a lot about storm-induced outages.

Yes, the lights flicker and dim before an outage. Yes, the power typically comes back on for a moment, or up to five minutes, a time or two before the final outage. This is due to intermittent connections as wires fail, and/or automatic switching in the grid.

I've never had, and never heard of anyone who has had, damage due to this sort of thing. I would unplug computers (back in the days before laptops) and TV's if I knew it was coming. Beyond that, not much you need to do.

And of course, the DC side is fairly well isolated from these sorts of things, assuming we're still not talking about a lightening strike. Sensitive DC electronics would normally be powered off when on shore power anyway.

Hey, if you're living aboard, and want to feel better weathering a storm with the power cord unplugged, no reason not to. But if you're away from the boat, it's better plugged in than unplugged.

jhance · Nov 30, 2017

CaptTom said:
I think we may be missing the definition of "brown out." To me, that means a sustained low-voltage situation introduced by the power company during times of critical demand on the grid.

In that case, motors like fans and compressors might be working a little harder. But presumably voltage is not lowered enough to damage them in normal use.

So let's move on to voltage surges (spikes) and sags. I live at what used to be the far end of a 15-mile-long line from the nearest substation, along a tree-lined, winding road. Suffice it to say I know a lot about storm-induced outages.

Yes, the lights flicker and dim before an outage. Yes, the power typically comes back on for a moment, or up to five minutes, a time or two before the final outage. This is due to intermittent connections as wires fail, and/or automatic switching in the grid.

I've never had, and never heard of anyone who has had, damage due to this sort of thing. I would unplug computers (back in the days before laptops) and TV's if I knew it was coming. Beyond that, not much you need to do.

And of course, the DC side is fairly well isolated from these sorts of things, assuming we're still not talking about a lightening strike. Sensitive DC electronics would normally be powered off when on shore power anyway.

Hey, if you're living aboard, and want to feel better weathering a storm with the power cord unplugged, no reason not to. But if you're away from the boat, it's better plugged in than unplugged.

I guess it's one of those things where if it has happened to you, you take extra precautions, but if you haven't had any issues you might not worry about it. Like I said, I've experienced fried motors, computers, electrical boards from brown outs (power sags if you want to call it that). So I'm extra cautious here. I live 20 minutes away from my boat so shutting off shore power for 24 hours then turning it back on after the storm passes... I feel this is a good practice. Doesn't do any harm and potentially saves onboard systems. I guess i cant be convinced that a high probability of having frequent surges/sags coming into my boat, in any form, is a good idea. Its like hooking up to a marina shore power with faulty electrical... forget it! I'd rather use battery power for a few hours until I can be guaranteed steady, consistent power. To me, it's not worth the risk, but to each his own. ?

sunchaser · Nov 30, 2017

JHC
Do you shut off power to your house too when storm clouds appear?

dhays · Nov 30, 2017

jhance said:
I have on my AC main, battery charger/inverter, and AC receptacles powering a fan and two low-watt heater/fan units.

The issue isn't necessarily at my marina. My common sense tells me to minimize allowing highly-fluctuating voltage into ANYTHING electrical - boats, at home, etc. I've seen motors and electrical gizmos have big issues in those situations. I figure there's no point to risk it and no harm done in shutting off shore power before an approaching storm that will likely result in one or many electrical anomalies. Good to hear many of you don't have issues... maybe this is more of an "island" worry!

You may be right about being more at risk for power fluctuations on the island. I wouldn't worry about it much though in my case. The only high-value item that may be at risk would be my inverter/charger but I'm not sure it actually would be. I keep some small dehumidifiers running on the boat and the resistance oil pan heater. Those wouldn't be affected.

Now, if I lived right next to the marina, I would be more inclined to disconnect shore power temporarily during a storm, but I'm not so I don't worry about it.

jhance · Nov 30, 2017

sunchaser said:
JHC
Do you shut off power to your house too when storm clouds appear?

I shut off any expensive equipment of which I don't want heavy fluctuating electrical input, certainly. Wouldn't you? If you were told the electrical entering your boat is going to be fluctuating wildly, would you not worry and leave your boat connected? I don't think so. I'm not talking about storm clouds. I'm talking about a heavy wind event with certain fluctuations in power. We live in the islands and deal with this regularly. In fact our power company has advised to turn off expensive equipment during such storms because people in our area have experienced property loss as a result (including me). Must be an island thing. Nobody here seems to have this worry.

psneeld · Nov 30, 2017

Most of the time the on off switch works fine except for lightning strikes.

So only keep critical stuff on if away, unplug if you are close by and worried.

12 years living aboard and spikes, surges, browniuts in some not so great marinas or residence docks have never seen an issue.

CaptTom · Nov 30, 2017

jhance said:
I live 20 minutes away from my boat so shutting off shore power for 24 hours then turning it back on after the storm passes... I feel this is a good practice.

It won't hurt anything, that's for sure. I will say it's not a bad practice.

I only live 15 minutes from the boat. I personally wouldn't drive down there (twice) just to unplug and re-plug it.

That said, I don't leave any 120VAC motors or computers powered up while I'm away. Most everything on the boat is 12V except resistance heating elements like the range and water heater. Electronic components (in the fridge, for example) don't run on 120VAC, and presumably have a power supply that's built to deal with being connected to dirty power from time to time.

The only thing left to worry about would be the inverter/charger. The off chance of a sudden leak causing the pumps to drain the batteries in less than 24 hours, while rare, would seem to me a higher risk than voltage fluctuations impacting the inverter/charger.

You make your best judgement and take your chances. No right or wrong way here.

diver dave · Dec 1, 2017

Lightning mitigation is a lot like burgler alarms. No one needs them until they need them. I've been lucky with burglars, not so luckly with lightning. People are notorious for bad risk management.
I've got people in my neighborhood building fallout shelters, and others not putting on winter tires. Pick your battles.

On "surge strips". These have a very limited design capability. They will burn out in about one second if you supply, around 200Volts to a 120V rated strip. On the other hand, you can hit them with 2000 volts for 100us, and they will clamp the voltage to around 300Volts and survive. I know this, since I just tested about 20 MOV types with various pulse voltages up to 5kV. So, MOV's/surge strips have a valid place in our systems. But they don't do anything against brownouts (overheating motors), or long term overvoltage conditions, which are really difficult to protect against. You need either a auto tap line conditioner or a ferro-resonant type of transformer, either of which is big $ for 30A an up systems. If that is your threat, and its real, best disconnect the boat before these events. And, you can leave the ground connected.

diver dave · Dec 1, 2017

Utilities have ways to monitor these types of surges using equipment like this:

I saw one in use a couple of days ago.

If you are seeing surges, call the power company distribution help line and ask the tough questions regarding monitor and control of surges.

koliver · Dec 1, 2017

" Must be an island thing. Nobody here seems to have this worry."

Though I live on an Island not too far from Orcas, I have never seen a "brown out" here, nor in Vancouver, where I have kept my boat since 1986, nor in Tsehum Hbr, (where Tom has his boat), where I kept mine from 1977 to 86.
If there is a power outage, I can't predict it, so have never done a preventative disconnect.
In all those years, I have seen one lightning strike on a moored boat. This was at Reed Point Marina in Port Moody. Not predictable either.

jhance · Dec 1, 2017

diver dave said:
Lightning mitigation is a lot like burgler alarms. No one needs them until they need them. I've been lucky with burglars, not so luckly with lightning. People are notorious for bad risk management.
I've got people in my neighborhood building fallout shelters, and others not putting on winter tires. Pick your battles.

On "surge strips". These have a very limited design capability. They will burn out in about one second if you supply, around 200Volts to a 120V rated strip. On the other hand, you can hit them with 2000 volts for 100us, and they will clamp the voltage to around 300Volts and survive. I know this, since I just tested about 20 MOV types with various pulse voltages up to 5kV. So, MOV's/surge strips have a valid place in our systems. But they don't do anything against brownouts (overheating motors), or long term overvoltage conditions, which are really difficult to protect against. You need either a auto tap line conditioner or a ferro-resonant type of transformer, either of which is big $ for 30A an up systems. If that is your threat, and its real, best disconnect the boat before these events. And, you can leave the ground connected.

Amen. Disconnect if you are in an area that experiences predictable fluctuations in voltage. I really do think it's an island thing. It seems so obvious to me because I experience this every year for the last 30+ years. We have boats with large battery banks to run bilge pumps. Boat is designed, and can survive, 24 hours without an AC umbilical cord. Even in a catastrophic situation, at least on my boat, one pump on my boat could run for 60 hours straight before draining the batteries.

jhance · Dec 1, 2017

koliver said:
" Must be an island thing. Nobody here seems to have this worry."

Though I live on an Island not too far from Orcas, I have never seen a "brown out" here, nor in Vancouver, where I have kept my boat since 1986, nor in Tsehum Hbr, (where Tom has his boat), where I kept mine from 1977 to 86.
If there is a power outage, I can't predict it, so have never done a preventative disconnect.
In all those years, I have seen one lightning strike on a moored boat. This was at Reed Point Marina in Port Moody. Not predictable either.

Good to hear you have predictably good power, but us island folk don't always have that luxury. Wind storms around here are pretty much a guarantee to lose power and/or have some form of brown outs or flickering power. We're talking lights go dim for seconds at a time here kinda stuff. Gotta keep that outta the boat or any expensive equipment. Disconnect!

BruceK · Dec 1, 2017

I suspect variation in the mains electricity supply may be more frequent than thought. At home we have 5000L rainwater tanks with a pressure pump( of course we have supplied water, this was drought backup against water usage restrictions). I`ve noticed if we ever have an outage the pump runs when the electricity supply resumes. Recently the electrical substation serving our area was undergoing refurbishment, no electrical appliance seemed to experience issues, except the pump which would run sporadically, night and day, until the work finished. Some appliances may be more sensitive than others to supply variations.

OldDan1943 · Dec 1, 2017

Sounds like a tough situation. Do what you must to survive and preserve your boat.

Shut down shore power during storms?

Senior Member

Guru

Senior Member

Guru

Guru

Senior Member

Guru

Guru

Guru

Senior Member

Guru

Senior Member

Senior Member

Guru

Guru

Senior Member

Guru

Senior Member

Guru

Guru

Senior Member

Guru

Guru

Guru

Guru

Guru

Senior Member

Senior Member

Moderator Emeritus

Guru

Similar threads