SIMPSON SERIES 8 DAVITS - electric shock


Stefan Schaufert
 

Dear Amelians,
from time to time we get an electrical shock (for free ;-) when using the switches to lower or raise the dinghy AND have contact to the davids or wires.
Today I checked the units/ electric engines and wiring, but everything looks fine. No broken cables, no failure.
What can be the reason for the electric shocks from your point of experiences?
Thanks a lot for you appreciated ideas.

Best regards
 
Stefan
A54 #119 Lady Charlyette, currently Exumas


 

Experts will say that 24 volts will not shock you. I have dealt with 24VDC and never felt a thing. 

I suspect that you have a 220VAC device that has an internal fault delivering 220VAC to the 220 Earth which is connected to Bonding. The Simpson davits are also connected to Bonding.

I also suspect it is either an Inverter that was connected wrong, a device connected wrong to the inverter power, or a device or wiring failure.

You should be very careful.  

Best,

CW Bill Rouse 
Amel Owners Yacht School
+1 832-380-4970 | brouse@...
720 Winnie, Galveston Island, Texas 77550 
www.AmelOwnersYachtSchool.com 
Yacht School Calendar: www.preparetocastoff.blogspot.com/p/calendar.html


   


On Tue, Mar 23, 2021, 4:17 PM Stefan Schaufert <mail@...> wrote:
Dear Amelians,
from time to time we get an electrical shock (for free ;-) when using the switches to lower or raise the dinghy AND have contact to the davids or wires.
Today I checked the units/ electric engines and wiring, but everything looks fine. No broken cables, no failure.
What can be the reason for the electric shocks from your point of experiences?
Thanks a lot for you appreciated ideas.

Best regards
 
Stefan
A54 #119 Lady Charlyette, currently Exumas


Elja Röllinghoff Balu SM 222
 

He Bill 
Is it possible to install a 
residual current protection switch
 to remove such threats?

Best Elja 
Sm Balu 222

Von meinem iPhone gesendet


 

Elja,

There is one installed on the 220VAC panel, and there will likely be one at the marina shore power post.

This is the reason I concentrated on the Inverter circuit. Many inverters were installed on Amels after leaving Amel.
CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Wed, Mar 24, 2021 at 1:00 AM Elja Röllinghoff Balu SM 222 <Bijorka@...> wrote:
He Bill 
Is it possible to install a 
residual current protection switch
 to remove such threats?

Best Elja 
Sm Balu 222

Von meinem iPhone gesendet


Stefan Schaufert
 

Thank you Bill.

The shock is very rare, not heavy and feels like a electrical discharge (like from clothes etc.).

May be it is something like induction from movings/ friction?

Best regards
Stefan
A54 #119 Lady Charlyette, currently Exumas


Robert Giroux <rg@...>
 

Here you go.

 

 

Regards,

Robert Giroux

(202)262-5828

 

From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> On Behalf Of Stefan Schaufert
Sent: Wednesday, March 24, 2021 8:49 AM
To: main@AmelYachtOwners.groups.io
Subject: Re: [AmelYachtOwners] SIMPSON SERIES 8 DAVITS - electric shock

 

Thank you Bill.

The shock is very rare, not heavy and feels like a electrical discharge (like from clothes etc.).

May be it is something like induction from movings/ friction?

Best regards
Stefan
A54 #119 Lady Charlyette, currently Exumas


Bill Kinney
 

With all the dampness around a boat, I think it is fair to say that it can NOT be a static discharge from friction.

I have to disagree with the assumption that you can never feel a "shock" from 24VDC.  It is true you will not receive a dangerous amount of current, but under the right conditions you most certainly can receive a shock more than strong enough to feel.  I know I  have when working around batteries and bridged across the terminals with an arm wet with sweat. I wouldn't describe it as painful or scary, but it certainly is enough to get your attention. If you have a good path between the battery positive and across your body to battery negative you will feel a significant tingle, sometimes even from 12 volts. All it takes is a bit of dampness on each contact point, and it really helps if the damp has some salt in it.

Your boat has an ELCI installed as the master shutoff breaker, so you should already be protected against hazardous shocks from 220V.  But it is always a good idea to test these regularly.  They DO go bad.  And some of these devices do not work well with all types of inverters.  If you push the "test button" it should trip.  It is also possible, that post-factory wiring modifications could have bypassed this device or rendered it ineffective.

You are correct to worry about the consequences if it is 220 Volts.  That would be dangerous.  The next time you feel the shock, turn off any inverter, and stop the generator.  If you still feel the shock, it must NOT be 220V.  A multimeter will also tell you the voltage of the leaking current, without putting your body into the circuit!

These issues can be infuriating to track down, the ability to feel the shock can be very dependent on conditions, and the leaking current might come and go in complicated ways that are hard to piece together.

If the leaking current is from 24 Volts it is not dangerous to you, but it can cause serious corrosion issues to the boat. It is telling you tht the bonding/grounding system is not working correctly, and in fact might have multiple problems.  This is the most likely source of what you are feeling.

A 220V leak is unlikely, but it true, it is the other way round:  unlikely to damage the boat, but dangerous to you.  Becasue of this the possibility can't be ignored.


Stefan Schaufert
 

Dear Electricans,

thx a lot for your hints and thoughts.

I checked a bonding of the Davits. No bonding to see + more then 5K ohm between bonding and davits, no bonding in the wiring diagram. Motors are with 24V (mostly 26V).
I checked the residual current protection switches. They are working/ ok - and 220V is obviously not relevant.
Inverters are turned off most off the time (only on for hot water, cooking, with generator for washing machine, dryer or dishwasher) and both ALWAYS turned off when using the davits.
No unusual corrosion so far.
No electrical leaks (since appr. 1,5 years). Detector is working.

That is why it is a riddle (at least for me) and interesting to solve it.

Best regards
Stefan
A54 #119 Lady Charlyette, currently Eleuthera