Shore Power Switch - Which is Correct?

[Madehn]

I am in the process of adding a subpanel on my AC shorepower circuits and upgrading the old 30 amp input to 50 amps- this subpanel will handle the non inverter loads- (putting in an inverter / charger and 10kw genset at the same time). So i am almost completed but in wiring up my new shorepower switch i have come up with a question. My old shorepower selector switch has both neutral and hot wires run thru it- one set for ship and one for shore selection. The wiring diagram that came with my new 4 position switch (off/gen/Inv/shore ) has only the hot wire running through the switch. i have mapped the switch and it appears feasible to do the switch either way IE switching both neutral and Hot or just switching the hot. What is the consensus. For some reason i kind of lean toward switching both but i am not sure why.

[goboatingnow]

I would always switch both lines. you can never be sure polarities don’t get reversed etc.

[tkeithlu]

While you are at it run the shore power through a 1:1 transformer. They are not expensive, and will completely isolate shore power from your boat. This is where I got mine. It's been humming away for ten years.

https://www.newark.com/w/c/transform...%20transformer

[smac999]

is the boat now 240v? then you need to switch 3 wires. L1, L2, and neutral.

you must swtich the neutral. because the gen will have the neutreal to ground bonded insdie it. (or should be when you wire it) so if the gen neutreal is not switched. you end up with a perminate n-g bond on the boat which is bad.

[Madehn]

the boat is not 240v now. -- in looking at the transformers listed it looks like it will be close to $1000 for one big enough to handle the 50 amp service?

[CarinaPDX]

That sounds about right. Consider buying a multi-tap transformer that will allow you to connect to either 120VAC or 230VAC shore power with either moving some wires or a switch. It costs a bit more than a 1:1 transformer but is a great convenience when cruising.

Greg

[Cadence]

Originally Posted by CarinaPDX

That sounds about right. Consider buying a multi-tap transformer that will allow you to connect to either 120VAC or 230VAC shore power with either moving some wires or a switch. It costs a bit more than a 1:1 transformer but is a great convenience when cruising.

Greg

Center tap/ buck boost.

[Flatswing]

you must swtich the neutral. because the gen will have the neutreal to ground bonded insdie it. (or should be when you wire it) so if the gen neutreal is not switched. you end up with a perminate n-g bond on the boat which is bad.[/QUOTE]

I believe that The basic rule is: the neutrals return to ground at the original source. Therefore you need to switch the neutrals also with your selector switch so the neutral returns to shore on shore power, returns to the generator on generator power. In addition, you need to ensure that the neutrals for the inverter circuits return to the inverter and are not commingled with the other neutrals. Otherwise you will be tripping the shore ELCI at any marina that has recently upgraded it’s shore power supply since the new refs have them trip at (I believe) 30 mA.

You may not need a “inverter” position on your source selector if you have an inverter charger, it will “pass through” to the inverter circuits whenever it sees shore power and should automatically switch the neutrals to shore power at the same time.

[chasfgr]

Originally Posted by goboatingnow

I would always switch both lines. you can never be sure polarities don’t get reversed etc.

which I've found to be the case in about 40% of cases in the Med - Spanish and Frenche were consisitent, Italy diverse and N Africa dangerous.
Greece, Croatia and Turkey invariably correct.

[CharlieJ]

To be compliant, and safe, L1, L2 and N must be switched for the reasons given upthread.

Regarding isolation transformers: To be compliant, they must have an electrostatic shield that is connected to shore safety ground between the primary and secondary windings.

[David B]

Originally Posted by Madehn

I am in the process of adding a subpanel on my AC shorepower circuits and upgrading the old 30 amp input to 50 amps- this subpanel will handle the non inverter loads- (putting in an inverter / charger and 10kw genset at the same time). So i am almost completed but in wiring up my new shorepower switch i have come up with a question. My old shorepower selector switch has both neutral and hot wires run thru it- one set for ship and one for shore selection. The wiring diagram that came with my new 4 position switch (off/gen/Inv/shore ) has only the hot wire running through the switch. i have mapped the switch and it appears feasible to do the switch either way IE switching both neutral and Hot or just switching the hot. What is the consensus. For some reason i kind of lean toward switching both but i am not sure why.

Definitely both Active and Neutral - next best thing to pulling the plug, and ensures you are not caught out with a shore reversal.

You may also want to consider a galvanic isolator in the earth circuit. I went for one of these with remote monitoring. Well priced, well made and they will post to you.

https://www.safeshoremarine.com/asse.../details/6.pdf