110v Side Power Consumption Management

[Alex F]

After spending first night on our 420DB I was faced with a new challenge. The boat has 2 hot water heaters. Both are on the same side (stbd), but on their own breakers. I had them both on and had master stateroom AC/Heater turned on (it’s also on the same stbd side). After the components were on for couple of hours the stbd side breaker on the main AC panel tripped in OFF position. I reset the breaker and short while later it tripped again.

The dock side was fine since I had 110v coming to the panel on both sides. So, it was clear to me that this is internal issue that had nothing to do with the fact that I had 50amp splitting in to 2x30amps coming in to the boat.

I started isolating the issue by turning one component at the time and had noticed that each of them (original HWH, 2nd HWH, A/C unit) uses around 10AMPs. This is when I realized that I can’t have them on at the same time. After I turned off one HWH the system stayed ON the rest of the night.

This was a surprising discovery to me. I was accustom to these issues on my 320 that had only single 30amp line, but I was hoping that on the lager models SR got their act together and figured out the proper wiring for the potential loads. Even though you don’t see many boats of this size with 2nd HWH, but we see quite often bridge or cockpit A/C.

My question is, do some of you guys (who has similar size boats) have these issues and you also have to pick and choose what unit you have on at what time or is it just my boat?

 

[Sum Escape]

It's not just your boat. My master stateroom A/C, water heater, stove and cockpit A/C are all on the same circuit. Three of four of these running at the same time can sometimes (not always) trip the breaker. All four definitely will! Sometimes the breaker on the panel in the salon, sometimes in the transom locker, sometimes on the dock. Oh yeah, and if the admiral plugs in the curling iron, it may only take two of the four along with the iron! Welcome to the energy management club....

 

[rondds]

With all the extra draw you bigger boats produce, it amazes me that they actually downgrade these boats to max available 50amps rather than 30a x 2. I can run a 10.5g HWH, both ac units, plus the fridge, the battery charger and toaster oven or blow dryer (never tried both simultaneously) and not pop a breaker - I guess b/c the air condx units are on their own panel, which leaves 30 amps for all the other junk to run. And you have to pay $600 for your cable. Never made any sense to me.

 

[Alex F]

Ron,

She's equiped with 2x30amps. I'm just using the single 50amp splitter b/c I have only single 30amp and single 50amp in my slip. But, 50amp is not the issue as the lack of power supply for a single side of 2x30amp. In this case it's tripping only internal stbd side. If the dock side was tripping, then I would say that single 50amp is the issue due to the lack of extra 10amp.

 

[alnav]

Alex, have you tested for the problem while on the genset? I would do that before I eliminated shore power as potentially being the issue.

 

[Nehalennia]

Mine trips when I have the washer, dryer and tanning bed all on at the same time. I need a 480DB. I'm sure they don't have this problem.

 

[Alex F]

It's not just your boat. My master stateroom A/C, water heater, stove and cockpit A/C are all on the same circuit. Three of four of these running at the same time can sometimes (not always) trip the breaker. All four definitely will! Sometimes the breaker on the panel in the salon, sometimes in the transom locker, sometimes on the dock. Oh yeah, and if the admiral plugs in the curling iron, it may only take two of the four along with the iron! Welcome to the energy management club....

I guess, this is somewhat of a good news if it's not just my boat (I really didn't think it was, it wouldn't make sense). I'm thinking that maybe I can change the sides for my 2nd HWH with Washer/dryer to distribute the load.

Alex, have you tested for the problem while on the genset? I would do that before I eliminated shore power as potentially being the issue.

I honestly don't see the connection here. What will it change if I have the genny on?

When the breaker trips on the main panel my stbd side still has 110v coming in. This means my main source of power (shore power) is still alive. If I'll turn on the genny, all it will do is supply the same 110v to the boat, which I already have from the shore power. Am I missing something here?

Mine trips when I have the washer, dryer and tanning bed all on at the same time. I need a 480DB. I'm sure they don't have this problem.

Hey Todd,
I think you should be fine if you run Jacuzzi instead of the washer/dryer as it uses less juice....LOL.

 

[Hampton]

Doesn't sound like a shore power issue, but I see the point to trouble shoot. It seems to me it's flat out an overload issue. We had this on our 340 - with 2 30 amp lines.

Now, yes, we do monitor our power, but I don't like that you have to turn one HWH off. The only sure time to leave the HWH on is all night. It goes off for toaster, curling iron, blow dryer, bowling alley (joke), and any other resistance style heating implement (cockpit space heater on 340). We, generally, do not run the cockpit A/C and the forward A/C at the same time. If we do, we firewall them so they don't cycle and constantly SPIKE the amperage (at startup). Our salon A/C is on the stbd side. The other two and HWH are to port.

Long story short - move the 2nd HWH to the opposite side, if that provides a more equitable distribution for things you may tend to use at the same time. I would consider removing it. I mean, really, 2 HWH's? How many girls are you bringing along. Hell, you can't bring them, you have to stay near the source of shower water. You only have about 150 gallons, right?

The good news is that they heat up pretty quickly. You don't need to plan an hour in advance.

 

[rondds]

Related Question:
I was under the impression that somehow, the AC units communicate and there is a mechanism that prevents them from starting up at precisely the same time. Is that a myth? If so, what exactly is involved in "firewalling" them?

We've taken three consecutive showers (not "boat" showers, but real showers) and the 11 gallons is plenty. Never ran out. And my 14yo likes to soak.

 

[Alex F]

Doesn't sound like a shore power issue, but I see the point to trouble shoot. It seems to me it's flat out an overload issue. We had this on our 340 - with 2 30 amp lines.

Now, yes, we do monitor our power, but I don't like that you have to turn one HWH off. The only sure time to leave the HWH on is all night. It goes off for toaster, curling iron, blow dryer, bowling alley (joke), and any other resistance style heating implement (cockpit space heater on 340). We, generally, do not run the cockpit A/C and the forward A/C at the same time. If we do, we firewall them so they don't cycle and constantly SPIKE the amperage (at startup). Our salon A/C is on the stbd side. The other two and HWH are to port.

Long story short - move the 2nd HWH to the opposite side, if that provides a more equitable distribution for things you may tend to use at the same time. I would consider removing it. I mean, really, 2 HWH's? How many girls are you bringing along. Hell, you can't bring them, you have to stay near the source of shower water. You only have about 150 gallons, right?

The good news is that they heat up pretty quickly. You don't need to plan an hour in advance.

John,

My thoughts are the same pretty much on all counts, well ...except the girls...:lol:

I have to admit that the moment I found out about 2 HWH I was surprized. We were actually managing just fine with the little 6gal HWH on 320 and I'm sure we can do just fine with original 11gal HWH.

My plan A is to move the 2nd HWH to the port side. If that doesn't help my plan B would be rewire it and change the plumbing to run in parallel, so I can use one or the other. If that doesn't work, then of course the worst case scenario is to remove the 2nd one all together.