OCP for shore power inputs

[ValhowellPower]

Looking at a Grand Banks 49 circa 1995. I am trying to determine if the forward and aft shore power connections have an RCD and circuit breaker? It appears as if the is a plastic cover and just a fuse. I am hoping someone can help clarify.

 

[Comodave]

There should be, at a minimum, be a circuit breaker within 10’ along the wire from the inlet. Doubt if there is any RCD from 1995. You should also have a selector switch so that the unused inlet isn’t powered up.

 

[ValhowellPower]

I believe this is the current configuration. Thanks

 

[Diep]

The original set up would have a fuse behind the plastic cover which is in the hot leg at each inlet. Power runs from there to a fwd/aft selector and then to a main circuit breaker on the panel.

 

[cks]

Those two fuse holders are not some cheap fuse holder. They are a very high quality Mil Spec product.

The manufacturer is FIC Corp. FIC P/N 5900/11. FIC 5900-11 fuse holder

Ken Davis is a true friend to the boating community.

KEN DAVIS, Sales
FIC CORP
Phone: 301-881-8124
Fax: 301-881-0530
Email: kdavis@ficcorp.com
Website: www.ficcorp.com

This is the primary protection for the boat. Faster acting than a circuit breaker and more reliable. The cap contains a neon bulb indicating when the fuse is blown.

 

[twistedtree]

I'd have to double check but I'm pretty sure fuses are not acceptable for the incoming power. Both legs have to be fused, and if there is an over current event, it's important that both legs disconnect. It's unlikely that fuses will do that, so a double pole breaker is really what's needed.

 

[Fleming]

No need to double check, twistedtree, you're right. Both current carrying conductors need to open so a fuse doesn't meet today's standards. I would recommend removing the fuses and installing an ELCI (or RCD) breaker.

 

[Bmarler]

There are literally thousands of boats with fused shore power inlets. They’re perfectly safe if the rest of the electrical system is in good condition. I don’t know if I’d change it out unless I was upgrading the electrical system. Then I’d bring the whole system into compliance.
It’s a different story if the surveyor calls it out and the insurance company requires a fix.

 

[cks]

Before me starts ripping out…. Remember what this is for…., it is the main protection of the boat wire. Fuses are FAST acting . Breakers….. not so much.
Ken Davis at FIC is a wealth of knowledge. I recommend a conversation with him first. He knows the regulations etc.
Grand Banks only used the the best of everything & continued use of this product for a good reason…. And NOT because it was less cost. They deemed it to be the best way to go.
Valhowellpower, proceed carefully….

 

[Fleming]

ABYC didn't just pull the idea of opening both current carrying conductors on the main shore power connection out of their a$$ for no good reason. There are several fault scenarios off the top of my head that I can think of where only opening the ungrounded shore conductor will cause problems. A reverse polarity is one example, when opening only the hot would still leave power on the neutral. Just because Grand Banks did it that way 30 years ago doesn't mean it's right. You won't see those fuses on a new Grand Banks, you'll see a double pole breaker.

That's the thing about electrical work that keeps it interesting. There are a million ways to do things that work, but they're still wrong for a reason. Sometimes that reason becomes apparent quickly, sometimes it takes a while before you figure out why it was wrong.

 

[SteveK]

This would appear to negate a need for neutral to be fused once the hot is open.

 

[twistedtree]

This would appear to negate a need for neutral to be fused once the hot is open.

I'm not sure how you reach that conclusion, though in isolation that section may not be as clear as it can be.

It's purpose is to make sure that if you have two shore power connections, they never share a neutral. So if you have two 30A shore connections which is pretty common, they need to each have their own neutral, and it can't in any way be connected to the other circuit's neutral. It could be dangerous if one of the shore outlets is reverse polarity, and on any modern shore connection it will trip the RCD.

 

[SteveK]

TT, I can agree. If reverse polarity yes, but my thought is with selector switch neutral is disconnected, plus most panels have reverse polarity lights if nothing else.

 

[Diep]

Following since I have the same setup as OP right now. I know it isn't current ABYC compliant and is a worthy upgrade, but its a little way down my list right now.

Is it possible that TT is talking about 2 shore power connections simultaneously (Like 30A house, 30A A/C) and SteveK is talking about 2 connection points (Fore/Aft). That is how I am making sense of the conversation anyway.

 

[O C Diver]

If the main panel has a breaker that also disconnects the neutral, and the fuse is for a shorepower cable where the inlet to breaker panel is greater than 10' (as required by ABYC), does the fuse need to be replaced with a neutral disconnect breaker as one already exists (further down stream)?

Ted

 

[SteveK]

Following since I have the same setup as OP right now. I know it isn't current ABYC compliant and is a worthy upgrade, but its a little way down my list right now.

Is it possible that TT is talking about 2 shore power connections simultaneously (Like 30A house, 30A A/C) and SteveK is talking about 2 connection points (Fore/Aft). That is how I am making sense of the conversation anyway.

Good question as yes I am talking about two sources fore/aft chosen by selector switch, whereas my boat has three separate inlets that can all be used separately or combined 1-2 and 1-3.
Other than the 10 foot from inlet point I have not found any other reference to current discussion. That is keeping in mind that current regulation may not override previous standards that may have permitted a fuse only on hot.

 

[Fleming]

If the main panel has a breaker that also disconnects the neutral, and the fuse is for a shorepower cable where the inlet to breaker panel is greater than 10' (as required by ABYC), does the fuse need to be replaced with a neutral disconnect breaker as one already exists (further down stream)?

Ted

Yes, if you want to be ABYC compliant you need a main AC breaker that opens both current carrying conductors (hot and neutral) within 10 feet of the shore power inlet.

 

[twistedtree]

Following since I have the same setup as OP right now. I know it isn't current ABYC compliant and is a worthy upgrade, but its a little way down my list right now.

Is it possible that TT is talking about 2 shore power connections simultaneously (Like 30A house, 30A A/C) and SteveK is talking about 2 connection points (Fore/Aft). That is how I am making sense of the conversation anyway.

It doesn't matter. Best practice is that at no time should the neutrals of two inlets be connected. It doesn't matter if the inlets serve the same onboard circuit, or different onboard circuits.

 

[SteveK]

It doesn't matter. Best practice is that at no time should the neutrals of two inlets be connected. It doesn't matter if the inlets serve the same onboard circuit, or different onboard circuits.

Agree, but if there is a two pole selector switch like we have when switching from shore to generator then the two neutrals are never connected. The 10 foot rule can be in addition to this if the distance is greater than 10 feet from inlet, except as you posted before whether the latest standard changes the requirement decades old accepted.
The fuse on hot side protects the entire length and the selector switch opens the neutral.
New standards should not mean mandatory upgrade to previously approved/accepted installation.

 

[Diep]

Agree. I was taking Steve to understand that if your inlets feed a rotary selector it will switch both legs and be break before make. In this case the ABYC requirement for no shared neutral will be satisfied. With two simultaneously active supplies this will not automatically be the case and depends on how the panel or equipment is wired. *edit-cross posted with Steve saying this*

I also agree this is not material to the (modern) requirement to have double-pole protection within 10' of the inlet, which is clear.

 

[twistedtree]

The breaker/fuse requirements and the no-interconnected-neutrals requirement are two separate things.

A 2 pole breaker is called for so that both conducts open if there is a fault. Both get open because there is no guarantee that the pedistal, shore cord, and inlet are wired correctly and you could end up with reversed neutral and line on the boat. If they are reversed and there is a fault and all you have is one fuse in the line conductor, it will blow, but because you are reverse polarity, you neutral is hot throughout the boat.

That's the current best practice. Your call whether/when to upgrade any parts of an older system.