I have a '93 catalina 30 and noticed a strong shock when I touched the binnacle after starting the engine last weekend. Ground fault somewhere? Why would I only notice it when the engine (alternator) is running and not the house batteries?
Getting shocks from the binnacle when engine running
- Thread starter augsbut
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This is a big SWAG but check the route on your throttle cable and see if it's touching anything it shouldn't.
Not plugged into shore power but motoring back to dock. Didn't have time to investigate so going back tomorrow to start hunting.
I'd be checking inverter and any solenoids, electric iso switches, anything with a coil of wire. The inverter connects to the AC system so if you don't feel it with shore power it is probably OK. The coils can send a strong shock when they engage or disengage. Just like an auto ignition coil but not so much voltage. The shock would be either through a metal case or the control wires.
The Great Roosack predicts your electric iso switch is malfunction and "chattering" on and off and feeding high voltage back through the ignition switch.
The Great Roosack predicts your electric iso switch is malfunction and "chattering" on and off and feeding high voltage back through the ignition switch.
I can feel 12V current but would hardly call it a shock and much less a strong shock. You do not indicate if the boat is equipped with an inverter but I would eliminate the possibility that there might be stray 120V current traveling around. With the engine off turn the key switch on and see if you get a shock. If you only get a shock with the engine running check the voltage ouput of the alternator. Give a visual to all wires and cables to see if you notice something out of place or form. Do you have a 12V socket on the binnacle or a connection for instruments. Auto Pilot motor?
Thanks for the help. I'll report more after an investigation this afternoon. FYI, no autopilot, no inverter....
Was the shock continuous or just one hit (like you really want to experiment). The other thing I can think of is a depth finder which puts out a high energy pulse that could be felt.
You can get a strong sensation from 12V if for example you have wounds on your hands, and the resistance of the skin is not there to limit the current flow.
You can get a strong sensation from 12V if for example you have wounds on your hands, and the resistance of the skin is not there to limit the current flow.
IMHO
I don't think you could get anything from 12v that could be called a shock. You cannot even feel a direct 12v connection to your body, unless your grounded extremely well, and even then very minor. With engine running, and no inverter on board, I would look first and directly at the alternator. Recently I had a bad regulator, and the alternator was putting out 16+ volts. But still don't think that would be enough to cause what could be called a shock. An internal short of some kind in the alternator could put AC into the system, and if you felt much of a shock, pretty sure your looking for AC voltage.
I don't think you could get anything from 12v that could be called a shock. You cannot even feel a direct 12v connection to your body, unless your grounded extremely well, and even then very minor. With engine running, and no inverter on board, I would look first and directly at the alternator. Recently I had a bad regulator, and the alternator was putting out 16+ volts. But still don't think that would be enough to cause what could be called a shock. An internal short of some kind in the alternator could put AC into the system, and if you felt much of a shock, pretty sure your looking for AC voltage.
Re: IMHO
I am inclined to give credence to Bill Roosa and the inductive discharge spikes. But there aren't very many coils on a boat. Phillip you remember the power supplies for car radios that used a vibrator that would switch the DC on and off to drive the transformer for the high voltage side of the vacuum tubes?
I am inclined to give credence to Bill Roosa and the inductive discharge spikes. But there aren't very many coils on a boat. Phillip you remember the power supplies for car radios that used a vibrator that would switch the DC on and off to drive the transformer for the high voltage side of the vacuum tubes?
I remember
Ross, I do remember those things. WOW Long time ago. My thinking was that it would take two things to happen for some kind of coil to give a shock. First the coil itself would have to be shorted internally, and there would also have to be some kind of short to the case or housing for it to get to the rest of the system. If a diode in the alternator blew, or shorted to the alternator case, it would be connected to anything on the boat that is grounded. Wouldn't rule out anything, but seems like that is a more likely cause. Of course, there are many on this board who are much more knowledgable in this stuff than myself.
Ross, I do remember those things. WOW Long time ago. My thinking was that it would take two things to happen for some kind of coil to give a shock. First the coil itself would have to be shorted internally, and there would also have to be some kind of short to the case or housing for it to get to the rest of the system. If a diode in the alternator blew, or shorted to the alternator case, it would be connected to anything on the boat that is grounded. Wouldn't rule out anything, but seems like that is a more likely cause. Of course, there are many on this board who are much more knowledgable in this stuff than myself.
12 volts can absolutely shock you. Think about a dead short across the battery. My brother once got a shock from a battery that spot welded 2 links of a wrist watch together while working on a tractor. Ever try to start your engine by hot-wiring across the solenoid of the starter. Big spark!! I'd check all the circuits to the binnacle and also see if there is any voltage to the steering cables and engine controls. A wire could easily chafe through the insulation.
There is a vast difference between electrical shock and electrical burns. learn of the difference.
Prime Time, While I will not say what you are describing is incorrect I believe what we are describing is putting your fingers across the battery terminals not some piece of metal.
Coils on a boat: iso solenoid, engine stop solenoid, some types of buzzers, depth finder transducers, any motor (low probability here though), starter solenoid, knot meter transducer, tach sender unit and of course the alternator (also low probability here too)
Coils on a boat: iso solenoid, engine stop solenoid, some types of buzzers, depth finder transducers, any motor (low probability here though), starter solenoid, knot meter transducer, tach sender unit and of course the alternator (also low probability here too)
Under the right conditions you can get significant effects from very low voltages. During surgery a heart can be stopped by having equipment plugged into circuits that are a few hundred millivolts different in ground potential.
If you take an ohm meter and measure your resistance through dry skin you may get about 200,000 ohms. Once the skin is pierced the body fluids (about as salty as sea water) conduct fairly readily. If you want a demo try connecting 12 volts to your tongue. Note that you need to apply both + and - to that organ for the full experience.
If you take an ohm meter and measure your resistance through dry skin you may get about 200,000 ohms. Once the skin is pierced the body fluids (about as salty as sea water) conduct fairly readily. If you want a demo try connecting 12 volts to your tongue. Note that you need to apply both + and - to that organ for the full experience.
From a medical perspective, A burn from electrical injury is "shock".Ross said:
A traumatic physical state caused by the passage of electric current through the body. It usually involves accidental contact with exposed parts of electric circuits in home appliances and domestic power supplies but may also result from lightning or contact with high-voltage wires. The resultant damage depends on the intensity of the electric current, the type of current, and the duration and the frequency of current flow. Alternating current (AC), direct current (DC), and mixed current cause different kinds and degrees of damage. High-frequency current produces more heat than low-frequency current and can cause burns, coagulation, and necrosis of affected body parts. Low-frequency current can burn tissues if the area of contact is small and concentrated. Severe electric shock commonly causes unconsciousness, respiratory paralysis, muscle contractions, bone fractures, and cardiac disorders. Even passage of small electric currents through the heart can cause fibrillation. About 1000 persons in the United States die from electric shock each year. Treatment may involve such measures as cardiopulmonary resuscitation, defibrillation, and IV administration of electrolytes to help stabilize vital functions. See also cardiogenic shock, hypovolemic shock.
Mosby's Medical Dictionary, 8th edition. © 2009, Elsevier.
Lets try and stay on topic folks. I'm sure we all will agree that taking probes attached to batteries and sticking them in our bodies is not going to help diagnose the problem.
Augsbut, what exactly were you touching when you got the shock? Certainly you felt it enter your hand, where did it leave? I'm thinking the same hand as gelcoat is a pretty good insulator. Was there water on the cockpit sole?
Augsbut, what exactly were you touching when you got the shock? Certainly you felt it enter your hand, where did it leave? I'm thinking the same hand as gelcoat is a pretty good insulator. Was there water on the cockpit sole?
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