Bonding/Electrical Leak??

[eje]

I was sure how to title this post and I do know this has been discussed here before

I have a 35ish year old boat I've had about a year with, I believe, a mostly original electrical system. My zinc anodes have been eroding very quickly and my diver just said he felt a mild tingling on one of his fingers when he would touch the propeller (with both AC & DC power on).

I assume I must have current leaking to the green wire, but am not sure where to start looking.

Should I be looking for an AC or DC leak?
Any suggestions on how or where to start looking for this would be very helpful

[YANDINA]

If the diver felt tingling it has to be AC, DC does not cause tingling.

You need to make sure that the shore power ground lead is not connected to the shore power neutral.

Unplug the shore power end of your cable and with the main breakers all OFF on the boat measure the resistance between all the connections in turn on the plug you removed. If you see a low resistance on one pair that would indicate that the neutral and ground are joined and need to be separated.

In particular, boats using a house hold circuit breaker box will often have the neutral and ground bonded together since they have that feature available.

Having isolated the ground, add a Yandina Galvanic Isolator to minimize the electrolytic action that is eating your zincs.

[GordMay]

Originally Posted by YANDINA

If the diver felt tingling it has to be AC, DC does not cause tingling...

Both AC and DC can produce a tingling sensation, though it’s true that AC has a much lower threshold of sensation.

The average threshold of feeling, for 60Hz AC current, varies between individuals, from about 0.5 - 1mA. The threshold increases with increasing AC frequency.
AC shock [not painful and no loss of muscular control] occurs between ±1.2 - 1.8 mA.
Painful AC shock [some muscular control lost] occurs between ± 6.0 - 9.0 mA.
The average threshold of feeling [tingling], for direct current varies between individuals, from ±1.0 - 5.0 mA.
DC shock occurs between ±6.0 - 9.0 mA.
Painful DC shock occurs between ±50.0 - 75.0 mA

[eje]

Thanks, that helps - I'll start chasing AC

The diver did say it was just a mild tingling and only felt it in one finger that had some scar tissue from an old injury.

"In particular, boats using a house hold circuit breaker box will often have the neutral and ground bonded together since they have that feature available."

This might be my problem. My slip doesn't have a 30amp receptacle. I'm using an adapter to a household 15amp outlet. Not the best setup, I know.

[eje]

"In particular, boats using a house hold circuit breaker box will often have the neutral and ground bonded together since they have that feature available".

Here's an update-

I did buy a galvanic isolator but wanted to check for leaks before I installed it.

I found the green wire was connected to neutral someplace. After chasing awhile I found the leak in the air-conditioning circuit, the air conditioning unit is wired directly to the AC shore power inlet with it's own breaker. It looks like a household breaker box. I'm not sure what to do with the green wires at the breaker. Should I just disconnect them from the breaker & spice them together?

[YANDINA]

Yes, if it doesn't have a separate ground bar remove both from the neutral bar and connect them together.

[BillKny]

You REALLY need to have someone who knows boat electric systems look at your boat.

It is impossible for anybody here to give you advice that they can be sure is accurate and safe when the source of information (i.e., you!) doesn’t know what to look for and what is important to report.

[YANDINA]

Originally Posted by BillKny

You REALLY need to have someone who knows boat electric systems look at your boat.

It is impossible for anybody here to give you advice that they can be sure is accurate and safe when the source of information (i.e., you!) doesn’t know what to look for and what is important to report.

The photograph showed the neutral and the ground are connected together. I suggest that a photograph is a sure and accurate source of information.

[eje]

BillKny - thanks for the advice, hiring somebody would certainly be the easy route, but the ONLY way for me to learn & understand the systems on my boat is to work out these issues myself. Further, I've already figured out the pro who installed the AC unit didn't wire it correctly.

I'm a former aircraft mechanic. I've got a good basic understanding of electrical systems. Between the vast knowledge available on forums like this one & Nigel Calder's book, I'm confident I can work it out

[Ike]

I worked for many years in the Coast Guard Office of Boating Safety advising boat builders on US electrical standards. One thing we used to always point out; be very careful when installing AC household type appliances on a boat. On household appliances the Green Grounding wire is connected to the White Neutral wire. That connection needs to be removed. If the appliance has a metal case then connect the green wire to the case, or to a metal chassis of the equipment. The Green and white should never be connected together on the boat, if the source of power is shore power. The only place the green and white should be connected is at the source of power which is back at station where the power is generated. If you have a generator as a source of power then the grounding green wire is connected in the generator. Same if you are using an inverter, because they are the source of power and you need an alternative path back to the source in the case of a ground fault. Otherwise it will try to travel through you, or through the water.

Anyway, read Nigel's book and learn. There are significant differences between shore side electrical systems and onboard systems.

[goboatingnow]

Originally Posted by Ike

I worked for many years in the Coast Guard Office of Boating Safety advising boat builders on US electrical standards. One thing we used to always point out; be very careful when installing AC household type appliances on a boat. On household appliances the Green Grounding wire is connected to the White Neutral wire. That connection needs to be removed. If the appliance has a metal case then connect the green wire to the case, or to a metal chassis of the equipment. The Green and white should never be connected together on the boat, if the source of power is shore power. The only place the green and white should be connected is at the source of power which is back at station where the power is generated. If you have a generator as a source of power then the grounding green wire is connected in the generator. Same if you are using an inverter, because they are the source of power and you need an alternative path back to the source in the case of a ground fault. Otherwise it will try to travel through you, or through the water.

Anyway, read Nigel's book and learn. There are significant differences between shore side electrical systems and onboard systems.

I can say categorically that certainly on this side of the pond household appliances never ever have neutral bonded to protective earth inside the appliance.

In the US. The only time I saw something so bonded was a very old electric stove.

Note also if you have isolated means of mains supply , there is no return path through the water.

[Ike]

I can say categorically that certainly on this side of the pond household appliances never ever have neutral bonded to protective earth inside the appliance.

That's because on your side of the pond they do it differently. Not right, Not wrong, just different. As I point out on the electrical portion of my website, there are many ways to configure the electrical system on boats. The only real concerns are, does everything work properly, and is it safe, not just for you, but also for the boat and others around your boat. Unfortunately there are far too many people out there who DIY the electrical systems on their boats, that haven't got a clue. At least if they ask on this or other boating forum they are likely to get some good solid advice.

[GordMay]

Originally Posted by goboatingnow

I can say categorically that certainly on this side of the pond household appliances never ever have neutral bonded to protective earth inside the appliance.

In the US. The only time I saw something so bonded was a very old electric stove.

Note also if you have isolated means of mains supply , there is no return path through the water.

In North America, it is permissible to bond the neutral to the frame, only on major appliances, such as dryers and oven/range, when installing on old wiring, with no ground.
This was a compromise worked out with the appliance industry, who feared losing sales. The rationalization is that dryers and ranges are rarely unplugged and moved, so a neutral wire failure is unlikely.
Better explanation here:
Bonding Frames of Major Appliances ➥ http://adamselectric.coop/wp-content...Appliances.pdf