Change out ship service power from 30 amps to 50 amps.

[Triskele]

I have a 1981 43 DCMY. It has two 30 Amp shorepower connectors. One for ship service and the other for HVAC. Has anyone ever upgraded from 30 Amp to 50 Amp for ship service? I live aboard and in the winter am constantly having load balancing problems. Am only able to run a couple of appliances at once. Can never have the water heater, stove, refrigerator, microwave, and space heater running at the same time without popping breakers or blowing shorepower fuses.

Anyone have experience with this upgrade? I'm thinking it should be doable by changing to a 50 Amp shore power connector and upgrading the wiring from the connector to the breaker box. Thoughts?

 

[Boatsb]

When you do the upgrade you need to make sure you have breakers at the inlet or close enough to meet abyc. I believe it's 10 foot max cable length.

Also the 125/250 brings in 2 x hot but only 1 neutral. It needs to be sized according to the use. If your using only 120 v loads I'd run 2 seperate neutrals that tie together at the breaker / inlet.

 

[q240z]

I did that upgrade on my Chris Craft Commander 42, which also came with 30a service originally. It was a short run (<3'), so no additional breakers were needed. If I recall correctly, I resized the wire to #6.

I'm curious what purpose two separate neutrals would serve, Boatsb. The two hot legs are typically out of phase, so the neutral never sees a double load of juice.

 

[Boatsb]

I did that upgrade on my Chris Craft Commander 42, which also came with 30a service originally. It was a short run (<3'), so no additional breakers were needed. If I recall correctly, I resized the wire to #6.

I'm curious what purpose two separate neutrals would serve, Boatsb. The two hot legs are typically out of phase, so the neutral never sees a double load of juice.

They do get all the 120 v juice. Even though phase will supposedly neutralize the extra amperage they always seem to be the weak link in the conversion. I've seen too many neutrals fried on cords and boats to overlook them. I'm very careful to have a full neutral leg on each circuit. They tie back at the breaker so there's no chances taken.

 

[Boatsb]

It*must*be on a two pole circuit breaker. This ensures that the circuit is two different legs and not just one, also the entire circuit will be disabled with only one breaker. Each hot leg returns on this shared neutral. The reasoning is that no more than the rated (breaker) current will pass through the neutral in this configuration. The two "Hot" legs will tend to balance the return current. Example: If both legs draw 5A, then no return current passes through the neutral. If leg 1 draws 3A and leg 2 draws 10A then the difference, 7A is returned through the neutral.

When using 2 cords with a y adapter you may have all the loads on the same phase. That would share the neutral.

If you were to share a neutral with two breakers on the same leg of a panel, both circuits could draw the breaker limit making the neutral 2 x the amperage. That will exceed the limit of the wire size and could cause a fire. Also, GFCI breakers will not work on a shared neutral circuit.

 

[bobk]

You might want to keep one of the thirtys for times when there is no need to break out the fifty. The latter are quite heavy. My 48 was wired that way by Hatteras.

Bobk

 

[Pete]

I believe the best practice for installing a single 240v/50a inlet to service two existing 30 amp 125v/30a panels would be to install a 4 pole ganged 50 amp breaker very close to the boat side inlet that disconnects all 4 wires bringing shore power on the boat. Upgrade the wire to each 120v/30a panel with #6 marine wire, minimum insulation rating 300 volts. Change out the two main panel breakers to 50 amp switching the hot and neutral. Then inspect the two panels for any #10 or #8 wire and replace this with #6. And daisy chain the single incoming neutral wire off the load side of the 4 gang disconnect breaker to serve each breaker panel. I believe you could then sleep well. I see no advantage to two neutrals on the boat, as they have to come together on the single neutral pin on the shore power inlet and then connect to shore power using the single #6 in the shore power cable. That is my two cents.

Pete

 

[Boatsb]

I believe the best practice for installing a single 240v/50a inlet to service two existing 30 amp 125v/30a panels would be to install a 4 pole ganged 50 amp breaker very close to the boat side inlet that disconnects all 4 wires bringing shore power on the boat. Upgrade the wire to each 120v/30a panel with #6 marine wire, minimum insulation rating 300 volts. Change out the two main panel breakers to 50 amp switching the hot and neutral. Then inspect the two panels for any #10 or #8 wire and replace this with #6. And daisy chain the single incoming neutral wire off the load side of the 4 gang disconnect breaker to serve each breaker panel. I believe you could then sleep well. I see no advantage to two neutrals on the boat, as they have to come together on the single neutral pin on the shore power inlet and then connect to shore power using the single #6 in the shore power cable. That is my two cents.

Pete

Pete the point is not to daisy chain but put a neutral to each 120 v source at the breaker.

I've done this more than once. I've never had an issue with a surveyor not approving it either.

 

[Triskele]

Guys....thanks so much for your info. This is a lot to digest. A bit of a neophyte (bit is an understatement) when it comes to this type of upgrade. Trying to get my head around the discussion. The characterization of the circuitry is apparently understood by those sharing this thread. As for me, I am needless to say confused. When talking about wiring and changing breakers, I'm not sure if you are always referring to the panel in the boat or the fuses at the inlet. Obviously, the fuses at the inlet need to be upgraded to 50 amp, but not sure why the breakers at the panel. So far, I am not having problems popping breakers at the panel so much as I am blowing fuses (and melting fuse holders) at the inlet. However, I can imagine the benefit of upgrading to a two pole 50 amp breaker at the box. What could it hurt? Thanks to this forum and its aptly capable members, I am now more aware than prior to starting this thread that I have more research and investigation to do before embarking on this task. Does anyone know of a schematic or electrical diagram of wiring for 50 amps they can recommend in this case?

BTW...any thoughts on how difficult it is to run #6 wire from the inlet to the breaker box on this vessel(43 DC). I find all wiring to be tight and like a birds nest. If I tie the new wire to the old, how difficult will it be to pull it to the box (breaker)?

 

[Triskele]

In changing out the inlet shore power socket, is it possible to replace the 30 amp inlet plug with a 50 amp inlet plug or does it also require replacing the stainless steel cover and case as well in order for the 50 amp plug to fit? According to Hubbell tech support, I will need to buy the 50 amp stainless steel case as well. Did others find this to be the case (situation)? Just looking to verify the info I am getting from Hubbell.

 

[Boatsb]

In changing out the inlet shore power socket, is it possible to replace the 30 amp inlet plug with a 50 amp inlet plug or does it also require replacing the stainless steel cover and case as well in order for the 50 amp plug to fit? According to Hubbell tech support, I will need to buy the 50 amp stainless steel case as well. Did others find this to be the case (situation)? Just looking to verify the info I am getting from Hubbell.

The outlet and the stainless shells are matched. You need a new one to change go a different outlet.

Maybe this is a job for a pro. It can burn up a boat and if your not knowledgeable of electric systems could have a bad outcome.

 

[Pete]

Scott, I see absolutely no technical problem with running a separate neutral from the shoreline disconnect to each main breaker in the two sub panels. I just do not think it is necessary. My thinking is the same for the green wire earth ground.

Triskele, my suggestion is to assume you will have to replace everything from the shore power inlet to the two breakers in your sub panels including any wire in between, plus any #10 or #8 wire in each sub panel. My SWAG for parts cost alone is close to $3K, without labor. I am also including two new rotary source selections switches as I am not sure the current ones are rated at 50 amps. This is a big job and doing it correctly is mandatory. And you will not be able to slide wire through to replace the old ones. To their credit Hatteras firmly secures the wire with closely spaced clamps.

Now I am up to 4 cents.

Pete

 

[Boatsb]

Scott, I see absolutely no technical problem with running a separate neutral from the shoreline disconnect to each main breaker in the two sub panels. I just do not think it is necessary. My thinking is the same for the green wire earth ground.

Triskele, my suggestion is to assume you will have to replace everything from the shore power inlet to the two breakers in your sub panels including any wire in between, plus any #10 or #8 wire in each sub panel. My SWAG for parts cost alone is close to $3K, without labor. I am also including two new rotary source selections switches as I am not sure the current ones are rated at 50 amps. This is a big job and doing it correctly is mandatory. And you will not be able to slide wire through to replace the old ones. To their credit Hatteras firmly secures the wire with closely spaced clamps.

Now I am up to 4 cents.

Pete

I guess if nothing ever goes wrong it's fine. Daisy chaining is not my way of doing things as it creates a single point of failure for multiple systems. You do as you like. My last coat guard inspected vessel prep for a customer passed with only on circuit length question that I had to show was shorter than their measurement allowing for inclusion in the 3% voltage drop for electronics.

By the way tie the 2 panels neutrals together after running seperate lines and you have more redundancy.

 

[Pete]

Scott, lets go one level deeper into the details so maybe you can better appreciate why I believe a daisy chain wiring is as good as or superior to the two home run neutral cables that you prefer.

Let's start with the daisy chain approach. Starting at the sub panel furthest from the shore power inlet, you connect a #6 white wire to the neutral buss, in a separate hole with its own compression screw. Another #6 neutral is connected to the neutral buss in sub panel 1 and terminated in sub panel 2 again each in a single hole with a single compression screw. A neutral from the buss in sub panel 2 then proceeds to the disconnect breaker. On this breaker there is one wire on each side and then the neutral connects to the neutral terminal on the rear of the shore power inlet. Note that the first three connections are each single wire connections protected in sealed enclosures. The disconnect breaker and shore power termination each have a single wire per terminal. In summary each termination of the #6 neutral wires is a single wire termination.

Comparing the daisy change to the twin home run approach, the two home run wires have to be spliced together somewhere before the disconnect breaker, since the breaker will not accept two #6 boat finely stranded wires on a single terminal. Thus an addition junction that ties together 3 #6 wires is required, perhaps an addition terminal bus. Regardless of how this junction would be accomplished it would be outside the sub panel environmental protection.

Can the home run approach be done with the similar environmental protection? Sure but why and for what cost?

I rest my case.

Pete

 

[Boatsb]

Wow.

I didn't know that the breakers with 1/4 studs were hard to find. Or that crimped ring terminals would not go on them heat shrunk and fully protected as part of a 3 breaker main shut off in an appropriate enclosure. Don't forget proper strain relief.

Whenever I upgrade services I add in the proper panel within a few feet of the inlet as required by the abyc and cg.

I don't know if the daisy chain approach is legal but it would definitely lengthen the circuit and depending on where the panels are lengthen it enough to go past the wire size recommendation.

 

[Pete]

Bobsb, just a curiosity question. Do you daisy chain 20 amp wall outlets or home run each of those back to the breaker panel. If you daisy changing these, what makes this a good idea for 20 amps (hot. neutral and ground), but not a good idea for a split phase shared neutral at 50 amps?

Pete

 

[Boatsb]

That's a single circuit and not two legs. Its also not the feeder. If I can run a home run I probably would but for outlets it's not always practical.