Stray Current Question

[msd58]

Today while taking off my prop off my 1995 2655 Bayliner I felt current coming from the stainelss prop when I touched it. It was not a shock, but I could feel it. The boat is on a trailer now. I did have a Marinco pigtail plugged into the shore power outlet on the boaand an extention cord from the pigtail to the outlet in the boat yard. The cord was not a three plug. Just standard two prong. I did have the battery charger on. Do I have a problem here? I have no real coorosion problems and zincs from last season look the same as the before. Boat stays in water May-November.

Much Thanks.

 

[bruceb58]

Re: Stray Current Question

You could be making a dangerous mistake by not using a grounded extension cord. You should also make sure you are plugged into a GFI outlet.

It sounds like you have a short to ground right now somewhere. it would be a good idea to isolate everything that hooks up 110V one at a time to see which circuit is the offender here.

 

[msd58]

Re: Stray Current Question

You could be making a dangerous mistake by not using a grounded extension cord. You should also make sure you are plugged into a GFI outlet.

It sounds like you have a short to ground right now somewhere. it would be a good idea to isolate everything that hooks up 110V one at a time to see which circuit is the offender here.

I will try a grounded extension cord. The power supply in the boat yard is just an outlet box with about 4 plugs on the box no GFI outlet. There is also a water spiggot there too.

 

[tommays]

Re: Stray Current Question

A ground is NOT going to solve this problem it is only there if things go wrong


There is a wireing problem with you AC circuts that can do really bad things to anybody swiming near the boat or even people in the boat


Tommays

 

[msd58]

Re: Stray Current Question

A ground is NOT going to solve this problem it is only there if things go wrong


There is a wireing problem with you AC circuts that can do really bad things to anybody swiming near the boat or even people in the boat


Tommays

I only felt the mild current when the power was plugged in.


PS thanks for all responses so far

 

[tommays]

Re: Stray Current Question

If it can PING you on dry ground it can do a LOT worse when its in the water and the shore power is pluged in

A ground is like a fireman it is not doing anything until things go wrong and if your getting pings touching the drive something is really wrong


Tommays

 

[Kevin W]

Re: Stray Current Question

Sounds like you found out why osha requires 3 prong plugs.
110V neutral is not always the same as earth ground and not always at 0V.

dump the 2 prong and go from there.

I get one of those polarity checkers.
maybe the boatyard was wired wrong.

 

[msd58]

Re: Stray Current Question

Sounds like you found out why osha requires 3 prong plugs.
110V neutral is not always the same as earth ground and not always at 0V.

dump the 2 prong and go from there.

I get one of those polarity checkers.
maybe the boatyard was wired wrong.

The boat has reversed polarity warning light on the breaker panel. It flashes green for normal and red for reversed. Its was green.

 

[Kevin W]

Re: Stray Current Question

I would get a GFI plug.
If you plug it in and it trips you know you gave an issue.
you can also use the GFI to troubleshoot.
If it does fail start by disconecting pluged in items on the boat until it does not trip the GFI.
I would start with maybe a battery charger?

 

[Texasmark]

Re: Stray Current Question

I saw a 911 true event on TV once where a family was building a boat dock. Everyone was out there having a big time. The son was sitting in the water attempting to use an electric drill which was not properly grounded.

It was not nice.

So do everyone there a favor and get the marina's wiring inspected by a qualified electrician.

Mark

 

[bruceb58]

Re: Stray Current Question

Because only a 2 wire extension cord was being used, nothing points to the marina wiring yet. Curious why everyone is blaming the marina wiring already.

 

[tommays]

Re: Stray Current Question

Most hand-held power tools have been Double-insulated and have used a 2 prong plug for a LONG time and still require a GFI in wet areas

The ground wire will not stop you from getting shocked in wet conditions

I repiar and weld in wash down areas everyday and pretty much know every way to get and electric buzz buy now

A GFI is the only way to be safe

A GFI should trip with the condition on this boat BUT will not fix the problem with the wireing that is allowing it to happen

Tommays

 

[MJ76]

Re: Stray Current Question

Whether the cord is grounded or not, the house or dock neutral should be held to ground potential. What you feel at the prop is voltage on the neutral with respect to ground. Easy enough to check with a voltmeter at the receptacle between neutral and ground, though I suppose you can't assume that just because the receptacle has a 3 prong plug that the ground is hooked up. Check it between neutral and that water sppigot you mentioned (if it's not plastic tubing). If you find voltage there, there's your problem.

 

[I/O WALDO]

Re: Stray Current Question

If the prop if hot ,something is reversed and/or knott grounded

 

[msd58]

Re: Stray Current Question

Because only a 2 wire extension cord was being used, nothing points to the marina wiring yet. Curious why everyone is blaming the marina wiring already.

I used a three prong extension cord today. Result was there was no current coming from the lower unit any more.

 

[Kevin W]

Re: Stray Current Question

Thats Good!
basically what can happen at some marinas id there is a large 110V load or an unballanced load on the circuit panel and the neutral becomes overloaded and becomes live AC.
it is low voltage ac but not 0V like earth ground.
the added earth ground added an aditional path to ground for this stray currrent and kept it way from you.

It is still possibe that you may have a problem but i would keep the 3 prong plug and watch your zink's .

 

[Kevin W]

Re: Stray Current Question

Ok I might stop blaming the marina now.
I had another thought.
most polarity indicators use the earth ground to check for reversal.
there was most likely enough electrolisys to light the light without a 3 prong plug. but i would guess that is where you got the poke from.
They draw about 1ma so it won't kill you but it will poke.

 

[bruceb58]

Re: Stray Current Question

I think it's pretty simple...your boat ground was floating above earth ground and that is why you felt a tingle. Could have been something as simple as your battery charger causing it after rectifying the AC. Most battery chargers output a lot of ripple. That along with the floating voltage potential is why you felt it. If you had measured the ground of your boat with earth ground on DC you could see the average float voltage. Measure on AC and you would have seen the ripple voltage.

 

[msd58]

Re: Stray Current Question

I duplicated what I did the week before and no current felt at all. Prior to that I talked to the mechanic in the yard and he said try a three prong cord, and that was it.

 

[I/O WALDO]

Re: Stray Current Question

Sounds like a potential shore power induced corrosion problem waitin to happen! Glad I'm not berthed near you!