Gen/shore Power Switch Guard
Gen/shore Power Switch Guard
Gen/shore Power Switch Guard
I can think of 4 things, all of which are very bad, that the interlocked switch prevents. Switching both on at the same time can result in:
1) If you are connected to shore power and have the generator running and join the two together: unless the shore power and generator just happen to be exactly synchronized, which is pretty unlikely, you will be creating a short circuit between the two. How bad it is will depend on how our of phase the two are, but it's a very anti-social thing to do. Breakers will likely trip all over the place.
2) If you are connected to shore power and have the generator running and join the two: in the freak situation where the two happen to be in phase and the join doesn't trip breakers, your generator will potentially be trying to power the entire community around you.
3) If just your generator is running and you are not connected to shore power: Joining the two will place live power on the plug end of your shore power cord and/or power inlet. Touching the exposed plug blades will kill you. The male and female ends of power connections are carefully chosen so the energized end is female. By joining the two you are reversing that and creating an serious hazard.
4) If you are on shore power and your generator is not running: Joining the two will energize your generator and turn it into an electric motor, attempt to start your generator, and do all sorts of other unexpected and dangerous things.
There is a really good reason for the interlocked breakers, or rotary selector switches, both of which ensure that only one power source is connected at a time.
I agree.
Some of the "experts" on this board do not seem to understand these things so it's important that those folks who do speak up.
what's so amusing is the one or two that don't even get that!!!!
There are one or two will fight to the death to NOT "get it." They just want simple rules with no variations or exceptions or messy details to confuse or frighten them. It's sad really.
It's our total lack of qualifications and a lifetime of doing things wrong that have forced our posts to be incapable of providing usefull information...
to be fair...both ends of the spectrum were correct.
You can't parallel the genset with shore power on boats without the right setup.
To say it CAN'T be done....well hopefuly that's worked out now.
It's the ones that keep going and don't understand that opposing views may not be discussing the same point that they are trying to make...well...
In the size boats most folks have paralleling the generator with shore power will never be an option.
There is simply no reason to attempt it, on a non commercial boat.
What is far more common is a following INVERTER , that can boost dock power or noisemaker output to start a heavy induction motor load.
In the size boats most folks have paralleling the generator with shore power will never be an option.
There is simply no reason to attempt it, on a non commercial boat.
What is far more common is a following INVERTER , that can boost dock power or noisemaker output to start a heavy induction motor load.
Folks can right size the noisemaker so it works harder and lasts longer.
12KW charging a battery set is not a happy diesel.
A second huge advantage is a smart inverter can have limits on power draw , and fill in as required, if desired..
So an old marina with 15A of 120V can start an air cond with out blowing the shore fuse.
Great for folks that travel off the main routes.
I'm not sure how it can be done with all inverters...not yet on my project list but probably there next year..
Darn, missed that one ... could use a few more laughs after reading some of the stuff here.But I can't resist...I love the one where if you touch the prongs of a 110 shore power cord you will DIE......man...I giggled myself to sleep last night...
No one ever said it should be done by everyone on every boat. The point is that someone said it could not be done, should not be done, and was illegal to do in any event.
I'm really confused here. Is all this because of the answer I gave a while back explaining the bad things that would happen if you engaged both breakers at the same time?
Or is it in response to something else that I missed?
I'm really confused here. Is all this because of the answer I gave a while back explaining the bad things that would happen if you engaged both breakers at the same time?
Or is it in response to something else that I missed?
I'm really confused here. Is all this because of the answer I gave a while back explaining the bad things that would happen if you engaged both breakers at the same time?
I don't think so. If your post #6 is the one, it is pretty good stuff.
I see now where the live prongs thing came from and if the boat plug is connected and if both the generator and the shore power breakers are closed - which is irrational - then that will energize the prongs but if the shore power breaker is open it shouldn't be an issue. None of the breakers, shore power or pedestal breaker should be closed until the cord is connected and secured anyway. If there is a reverse current issue the breakers will take the hit, not you.
............. On the live plug, the scenario I had in mind is gen running and shore power NOT plugged in. If you turned both breakers on, the prongs at the shore power inlet would be live and dangerous. And if you connected your power cord to that inlet, then the shore-end of the cord would now have live pins exposed. OK, the "die" part is a little hyperbole, but it would still be a pretty bad thing.
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My father in law (a farmer by trade) rigged a portable generator at his house as a backup. Instead of a transfer switch, he made a cord with male plugs at each end (a "suicide cord" in my trade). It stays plugged in at the generator and when the power goes out, he unplugs the electric dryer and plugs the male plug reom the generator into the receptacle. He turns off the main breaker, starts the generator, and has power in his house.
I tried to tell mim that this was a dangerous situation, but at his age and with his knowledge of electricity rolleyes, he thinks it's just fine. One day the generator will get started first or someone will unplug the dryer end with the generator running and that could well be the end of somebody. One day he will forget to turn off the main breaker and a lineman working on what should be a dead line may end up the same way.
There are a lot of people out there with little or no understanding of electricity. That's fine as long as they leave it to the pros, but some can't resist trying things and if they work, the thought is, that's a fine way to do it.
Or, as I will confess, you might know what you are doing and simply make a mistake. I once forgot to open the main service breaker when I activated my generator. The result was a feeble attempt by my generator to re-power the grid. The grid won and my generator lost.
We all all F&(*k up now and then, and that's why fail safes are a good idea.
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