Electrical

[bud37]

This is just a bad idea.......they call these things suicide/widowmaker cords for a reason. I don't recommend anyone make and use cords like this, there are way too many things that could and do go wrong.......

Most of these issues ( 240 power) come from not having the correct plugs/adaptors to match the boat side service to the dock side service....the isolation transformers if you have them are a great upgrade in my opinion, so many benefits.....

[Viper]

You do have to know what you're doing and consider the consequences of not shutting the mains off but it's doable with precautions. You also have to consider that modifying the cord leaves exposed prongs that are potentially live that you could inadvertently touch. You could overcome that by installing a 120V inlet usually used on smaller boats when AC is needed to power up a charger, a regular extension cord is used.

Hans, you have to be especially careful when doing this at home with a generator. It's illegal in some jurisdictions, only because you can backfeed the utility if you mess up by not turning off the mains. That could be fatal to any linesman working to restore power, that's why transfer or source switches are preferred at the main power inlet. For what we're discussing here in terms of getting power to your boat when only 120 volts is available, the outlet idea can work with some precautions or you can install the inlet below. Put it on its own breaker and only turn the breaker on when you're using that inlet or install a proper transfer, that way you don't light up those prongs with ship's power during the season. Just be mindful of the hazards and the precautions that must be taken. If you're unsure, don't do it!

[tomschauer]

Unless you have a really big kw generator, I don't believe you are going to hurt any linemen. If you forget to shut off your main, you will be feeding your neighbors and more than likely trip the output breaker on your genny instantly. Either way, the current will not back feed through the step down transformers and create high voltage on the power lines.
If the power comes back on and you do not have your main off, you will most likely blow off the power side of your genny and let all of the smoke out of the wires!

[Midnightsun]

I understand everyones issue with back feed, nothing wrong with doing so except you need to know exactly what you are doing. Cutting off the main is the first thing one must do. Unfortunately this world is made up of many idiots that have no clue, some even have run generators indoors or used bbq's indoors to heat the house that one reads about in the news because they killed themselves!

I did this way back in 98 after the ice storm of the century. I was lucky and came back on line after a few days. Salt water aquariums, 2 refrigerators and a freezer not to mention heat and hot water. My dad took a couple of weeks and my Honda 5000 ended up at his house where once again I back fead to get him up and running. My dad would never have figured out how to hook up a generator on his own, not that he is dumb, just was never interested or experienced in electrical.

I do not do this any more as I now have a fully automated 22kw standby generator on a 200a whole house transfer switch. Heck, can even charge the Tesla in a total outage. Ice storm of 98 https://en.wikipedia.org/wiki/January_1 ... _ice_storm

[Viper]

Source of the post Unless you have a really big kw generator, I don't believe you are going to hurt any linemen....

That's the thing though, you don't know, someone might be inadvertently powering up the grid with a high output generator. Some folks simply plug them into a welder or stove receptacle. That's a 50 amp circuit. The linesman can be working just down the street. Apparently it's one of their biggest fears. They can control the grid and shut down an area to be safe while they work but they have no control over what people do in their homes during a power outage. Again, as an emergency measure it's doable, you just have to know what you're doing. Since for the purpose of this idea here the boat is being powered up by the grid, inadvertently powering up the grid isn't a concern but there are still some things you have to be aware of as mentioned earlier. We're talking about a case on the hard requiring 240 volts with none available but 120V is.

Back to the original post, did you try a Reverse Y cord yet? To be sure, you can ask a neighbor to borrow theirs and try it before you invest in one.

[km1125]

Eons ago, I had started to do the 'backfeed' thing at my house. Went over to a neighbor's house one time to help him out to do the same thing. Shut off the main, plugged the genset into the dryer outlet and went to fire it up and instantly loaded down the generator to a crawl and then popped the breaker on the generator. There wasn't anything running in the house, so that didn't make sense. Checked everything and tried again. Same thing. Took the cover off his panel and found out the clearly labelled breaker that said "MAIN" was only feeding the 120VAC breakers in the panel. ALL the 240VAC breakers were tied directly to the incoming feed from the meter. Cut the security tag on the meter and removed it so we could make sure we were feeding JUST his house. I had never seen a stupid electrical panel like that before.

[Midnightsun]

Source of the post Eons ago, I had started to do the 'backfeed' thing at my house. Went over to a neighbor's house one time to help him out to do the same thing. Shut off the main, plugged the genset into the dryer outlet and went to fire it up and instantly loaded down the generator to a crawl and then popped the breaker on the generator. There wasn't anything running in the house, so that didn't make sense. Checked everything and tried again. Same thing. Took the cover off his panel and found out the clearly labelled breaker that said "MAIN" was only feeding the 120VAC breakers in the panel. ALL the 240VAC breakers were tied directly to the incoming feed from the meter. Cut the security tag on the meter and removed it so we could make sure we were feeding JUST his house. I had never seen a stupid electrical panel like that before.

Wow, you mean there was no cutoff to shut off the 240v from the meter? Cannot be a legal installation.

[km1125]

Source of the post

Source of the post Eons ago, I had started to do the 'backfeed' thing at my house. Went over to a neighbor's house one time to help him out to do the same thing. Shut off the main, plugged the genset into the dryer outlet and went to fire it up and instantly loaded down the generator to a crawl and then popped the breaker on the generator. There wasn't anything running in the house, so that didn't make sense. Checked everything and tried again. Same thing. Took the cover off his panel and found out the clearly labelled breaker that said "MAIN" was only feeding the 120VAC breakers in the panel. ALL the 240VAC breakers were tied directly to the incoming feed from the meter. Cut the security tag on the meter and removed it so we could make sure we were feeding JUST his house. I had never seen a stupid electrical panel like that before.

Wow, you mean there was no cutoff to shut off the 240v from the meter? Cannot be a legal installation.

Not a single breaker. You had to shut off all the 240 breakers to cut all the power from the panel. It was a 150A panel in a house built in the early 90's. Not sure if code then (or even now) requires a single breaker to cut all power. IIRC, there were four 240A breakers, for A/C, Dryer, Stove and "Main". The "Main" then fed 10-12 120VAC breakers for all the regular 120 stuff like lighting and outlets.

[tomschauer]

Split mains were pretty common on fuse panels and breaker panels into the 80's. I don't remember when the NEC shut them down, but I believe it was before 1990. Even after that you could continue to use these panels IF you had a disconnect before the panel.

[km1125]

Well, I just finished an adapter cord for my buddy's boat (the one with the isolation transformer). Just tied the hot from each 120VAC plug into each hot for the 240VAC connector and both the grounds to the ground of the 240VAC connector. I did NOT tie the neutrals together nor connect them to the 240VAC connector. This way, if one of the 120VAC outlets is "wired backwards" (meaning the neutral and hot are swapped), the only thing that will result is he'll see low voltage in the boat (roughly half of expected). If I tied the neutrals together and one of the 120VAC outlets was "backward", that would be an instant short.

Got the connector for $23 on Amazon and just used a couple old extension cords. One is longer because one of the outlets is typically farther away.

240VAC_adapter.jpg

Now, I'm wondering if it will actually work when connected to a GFCI-protected outlet. I'm thinking it might just trip it immediately.