Electrical ?- wire size from AC main breaker to neutral buss

[DCTracy]

Hello Tuggers,

Need some help.

I am trouble shooting a GFI trip problem on 2011 R25. Mechanic pulled off main AC/DC panel at the helm to access the wires. The incoming neutral and hot to the main breaker are #10. He noted that the neutral on the downstream side of the main breaker leading to the neutral buss was only 16 gauge and too small. Is he correct?

It seems like this is factory wiring in part because it is VERY hard to access the neutral buss since the boat is assembled, I don't think the boat electrical has been worked on and if so, don't know why someone would change that.

Will provide a photo as soon as I figure out how to upload. Do I need to load photo to a gallery first before inserting in this message?


Darren

 

[Wee Venture]

The main Breaker is inserted in the hot (black) feed - in and out. Your white #10 feeder neutral should go directly to the neutral bus. If there is a neutral (white) wire coming from this breaker it is only to allow a return path for the pilot light that glows to indicate the breaker is “on.” For this a #16AWG is more than sufficient. This is my understanding unless you have some sort of unusual setup that I haven’t encountered before.

John

 

[DCTracy]

Thanks for the reply Wee Venture. The white # 10 goes to the same breaker as the black #10 - a 2 pole breaker I believe. The only wiring connecting the downstream side of the double pole breaker to the neutral buss bar is the #16 white (neutral) that I described. It doesn’t make sense that a wire that small feeds the neutral buss bar.

It makes more sense that the neutral #10 go directly to the neutral buss bar as you describe. There may be a separate # 10 neutral that does that, but I can’t see - wiring is buried. But if that is the case, why the #10 neutral to the supply side of the double pole breaker with only a #16 connected to the downstream side of that breaker leading to the neutral buss? No AC wiring diagram in the owners manual to help me better understand what is going on.

Wish I could upload a photo to help paint the picture.

 

[BB marine]

The panels main breaker is a double pole main breaker. Newer boats should have the first double pole breaker installed ELCI this breaker should be installed within 10' of the boats shore power receptacle. The power panel should also have a double main breaker installed. The size of the triplex boat cable should be based on the length of the run and the service. In this case 30 amp, triplex 10/3 105C rating should be used if the cable is run thru the engine compartment.

The main feed wire size from the shore power receptacle to the ELCI then to the main double pole breaker in the panel to the Hot terminal strip, neutral terminal strip and the ground terminal strip in the panel should be the same size wire.

The feeder circuits protected with appropriate sized breakers can have smaller gauge wires based on the circuit load and protection.

In your description if a 16 gauge wire is coming off the neutral side of the double pole breaker to the neutral terminal strip it should be removed and a 10 gauge installed in place. This neutral needs to be the same size as the HOT

 

[Bruce Moore]

Hello Tuggers,

Will provide a photo as soon as I figure out how to upload. Do I need to load photo to a gallery first before inserting in this message?


Darren

There are two ways to embed images in your posts.

If the picture you want to include is in one of your gallery folders (on Tugnuts), click on the g2Imgbutton. That will open another window which will allow you to browse your galleries and select a picture. Be patient, it can take a while for the new window to populate. It should default to your album when it opens.

Click the box in the upper left of the picture you want to post. Scroll (way) down to the bottom of the window and click Submit. That will attach the picture to your post.

If the picture isn't in your gallery, perhaps something you've seen elsewhere on the web, or in another personal web collection (i.e. flickr, iCloud, google, etc.) then you click the Img button. The image/collection must be open to the public.

This will create the following string in your posting window - then you copy and paste the URL (http://whatever...jpg) of the desired image in the middle, between the ][ brackets. The trick here is to determine the direct URL of the image. Various image hosting sites show it in different ways. Sometimes it's right up in the address bar. Other times it's listed under "Share This Image", etc.

You can determine if you have the correct URL by hitting the Preview button. If it displays, you're good to go. If it's not correct, the form will give you some kind of clue so you can go back and dig around. You'll only have to figure it out once for each host.

Getting a User Photo Album is easy but it requires submitting a request from within the site structure.

1. Sign on to the site. You’re probably already signed in if you’re reading this.

2. Select the User Control Panel link from the upper left corner of any page. Note: On the home page, this link is in your user menu in the upper right.

3. Click the Usergroups tab, then select the radio button next to the User Albums group.
Scroll down, choose "Join selected" in the drop-down menu, and click the Submit button.

Once you do this, an email is automatically sent to the administrator (me). That message will trigger my ability to approve your request, and you'll receive an email indicating your membership in the User Albums group has been activated.

I'll watch for the message, and look forward to seeing your pictures.


Cheers,

Bruce

 

[Wee Venture]

Brian is absolutely right. What I said about a neutral wire only serving the pilot light would be true of a branch (single pole) breaker but not the main breaker. On our AC panel (Blue Sea Systems) the main breaker looks exactly like the branch breakers and I assumed it was single pole. Not so.

I believe the reason the neutral wire, along with the hot, is connected to a double pole breaker is because of the very real possibility of reverse polarity - either in the Marina wiring or the shore power connections to the boat. With a single pole breaker, if that happened, the boat wiring would still be hot even when the main breaker is switched off. So apparently it is standard practice for the main panel breaker, as well as the ELCI breaker, to be double pole. (In non-marine installations, neutral wires are not routed to circuit breakers, even the main panel breaker, unless it is a ground-fault type).

So thank you Brian for correcting me. And yes, I agree the neutral wire from the main breaker to the neutral bus should be the same size as the feeder wire, in this case #10.

John

 

[BB marine]

I believe the reason the neutral wire, along with the hot, is connected to a double pole breaker is because of the very real possibility of reverse polarity - either in the Marina wiring or the shore power connections to the boat. With a single pole breaker, if that happened, the boat wiring would still be hot even when the main breaker is switched off. So apparently it is standard practice for the main panel breaker, as well as the ELCI breaker, to be double pole. (In non-marine installations, neutral wires are not routed to circuit breakers, even the main panel breaker, unless it is a ground-fault type).

John, My opinion is identical to yours.