Shore power to boat - 50A or 100A

[Hatteras58]

I have always used only 50 A shore power service. I can't tell from the owners manual whether the boat was designed for just 50A service, plugged into either port or starboard receptacles, or whether we could actually have 100A of service coming in to the boat by using shore power cables on both sides. Forgive my ignorance of how this should work and I ask for some constructive feedback.

 

[MadHatter53]

On my boat the breakers on the AC panel have a safety slide so you can only have one side hot at a time. I do have three shore power hookups on each side, two 50’s and one 35amp but the breakers I think again only let AC service from one inlet as well.

 

[oscarvan]

Nope, I hope you can't do that on your boat.....

Somewhere you (should) have a selector switch that makes you choose. Having 100A/240 on a 50A/240 system would overload a lot of wiring, not to mention the possibility of it being out of phase.

And remember that 50A is at 240, so that's 50A each leg. You in fact already have 100A

Boats with multiple 50A/240 systems have multiple systems. Say A/C's on one and the rest on the other. They may be able to combine them on a single source, which would be the oppostie of what you're trying to do.

 

[Pascal]

My 53 was an early one with a very simple panel in the ER. Right now the new panel I did by the stbd PH door is only rigged for a single 50A which is barely enough. I m planning on adding a second 50amp to run the chillers and stove. If I ever need to run off a single cord I ll have a selector switch to send connect the single cord to both sub panels.

I thought most later hatts had the option to run either off one or two cords

 

[SKYCHENEY]

You can run 2 50a cords at once on most of these boats. If you have 2 isolation transformers then it is possible. You will see 2 50a inlets on each side of the boat.

YMMV depending on the vintage of the boat. We run 2 50a cords at our home dock. I feed Ships service 1 and 3 from one cord and ships service 2 from the second cord.

 

[davidwigler]

And remember that 50A is at 240, so that's 50A each leg. You in fact already have 100A

50 amps at 240 is 12,000 watts. 100 amps at 240 is 24,000 watts.

 

[davidwigler]

Each leg is 50 amps at 125, or 6000 watts.

 

[Photolomy]

You can run 2 50a cords at once on most of these boats. If you have 2 isolation transformers then it is possible. You will see 2 50a inlets on each side of the boat.

YMMV depending on the vintage of the boat. We run 2 50a cords at our home dock. I feed Ships service 1 and 3 from one cord and ships service 2 from the second cord.

Are you running them to starboard and port? Or does your boat have 2 x 50A ports on each side? Most do not. At least not the 53's. They have a single 240 50A and 2 x 120 30 A hookups on each side.

 

[JD5652]

You can run 2 50a cords at once on most of these boats. If you have 2 isolation transformers then it is possible. You will see 2 50a inlets on each side of the boat.

YMMV depending on the vintage of the boat. We run 2 50a cords at our home dock. I feed Ships service 1 and 3 from one cord and ships service 2 from the second cord.

I only run one 50A cord, but do have the capability to run two as Sky noted above.

 

[Hatteras58]

My configuration is receptacles on both sides of both, each with a single 240/120VAC 50A and two 120VAC 50A (not 30A). No isolation transformers. If I'm understanding the comments here, I could plug in 50A cords on each side but only able to use one at a time. BTW, thanks everyone for the information.

 

[Boatsb]

Get a hold of someone who actually knows what you have.

Call hatteras with your hull number and get the drawings. Get a good electrician to confirm its not been changed. Its not something I would best guess.

 

[SKYCHENEY]

Are you running them to starboard and port? Or does your boat have 2 x 50A ports on each side? Most do not. At least not the 53's. They have a single 240 50A and 2 x 120 30 A hookups on each side.

I have one 50a 125v and two 50a 240v on each side. On my friends 1978 60C, he has to run one cord to each side if he wants to energize both iso-trans and get 100a usable.

 

[oscarvan]

My configuration is receptacles on both sides of both, each with a single 240/120VAC 50A and two 120VAC 50A (not 30A). No isolation transformers. If I'm understanding the comments here, I could plug in 50A cords on each side but only able to use one at a time. BTW, thanks everyone for the information.

That's the way my boat is configured and you are correct. FWIW I never use the 120/50A connections. I have cables for them but it appears that marinas offering that service are far and few between. At some point (like when the deck/house get painted) they may come out.

 

[Pascal]

That's the way my boat is configured and you are correct. FWIW I never use the 120/50A connections. I have cables for them but it appears that marinas offering that service are far and few between. At some point (like when the deck/house get painted) they may come out.

In all these years and many trips up the coast I ve never seen a slip with 120/50. They may have been popular in the 70s and maybe 80s, like 8 tracks and Betamax.

 

[racclarkson@gmail.com]

They usually never draw 50 Amps unless on fire.

 

[Photolomy]

Marinas do offer 120 30 amp though, which also works with that setup, albeit at reduced power.

 

[davidwigler]

In all these years and many trips up the coast I ve never seen a slip with 120/50. They may have been popular in the 70s and maybe 80s, like 8 tracks and Betamax.

I have a Hubble adapter from 120/50 to 240/50 that allows me to use the second circuit for 6,000 watts and the transformer converts it to 240 volts.