Reverse polarity on shore power (O'Day 35)

[Rivatar]

if the plug at the marina end is not completely pushed in, the list sea air causes a short between the exposed prongs on the plug, and lights up the reverse polarity led on your control panel.

[ramblinrod]

Originally Posted by Rivatar

if the plug at the marina end is not completely pushed in, the list sea air causes a short between the exposed prongs on the plug, and lights up the reverse polarity led on your control panel.

A poor connection between the shore power cord and power post can cause the reverse polarity indicator to light, but this is not due to a "short" (circuit) or sea air (directly), it is due to an "open" circuit.

The neutral and ground connections on the vessel shore power cord, (when disconnected) should be open circuit. When the cord is plugged into the marina power post, these are connected (by the ground/neutral connection at the marina service).

If the ground connection at the power post (or vessel shore power inlet) is poor (open circuit), it may cause the reverse polarity indicator to light (even though line and neutral polarity is correct).

But in the case of the OP, there is no problem; he assumed the "test" switch was to test for a reverse polarity condition in his connection. It is not. It is to "test" the reverse polarity indicator.

If the reverse polarity indicator is working properly (as may be tested by operating the "test" switch if applicable) it will light the instant a reverse polarity (or may if "open" ground) connection is made at the power post, with the vessel main AC breaker in the "off" position (where it should be when the power post connection is made or broken) until the reverse polarity check is completed.

ABYC standards have called for reverse polarity indicators for many, many years. If your vessel is post ~1980 or has had AC panel modifications since, it should have one. If your vessel is older and doesn't have one, it is likely way past due an AC electrical panel upgrade.

[smac999]

Originally Posted by ramblinrod

A poor connection between the shore power cord and power post can cause the reverse polarity indicator to light, but this is not due to a "short" (circuit) or sea air (directly), it is due to an "open" circuit.

The neutral and ground connections on the vessel shore power cord, (when disconnected) should be open circuit. When the cord is plugged into the marina power post, these are connected (by the ground/neutral connection at the marina service).

If the ground connection at the power post (or vessel shore power inlet) is poor (open circuit), it may cause the reverse polarity indicator to light (even though line and neutral polarity is correct).

.

this issue is caused by a poor connection on the N, it would not light up on an open N. causing a voltage drop along the N wire. which only happens under AC load. the higher the load the higher the voltage drop. the brigher the light will be. if you have voltage drop along the N wire. that creates a voltage potential between the N and G wires on the boat. maybe ~5vac. which is enough to light up the RP light dimly.

so you end up with say 120v Hot to Ground, 115v H to N, 5v N to G. with 5vac across the bulb

it is pretty normal to see 1vac N-G as even with a good connection there will always be some voltage drop in the marina and shore cords. but it'll be equal drops on both H and N.

so you'd end up with like 119v H to G, 118 H to N, 1v N to G. 1V drop on each the H and N from dock. no V drop on G because there is no current.


or maybe it's the solar charger voltage doing it...

[zeehag]

unless you twist your plug to lock it into place, you will have reversed polarity.
try actually plugging in the cord, twist the plug into socket, THEN test it.
i use special surge protectors with notification of reversed polarity. they are pricey but worth it. only times it showed i had a problem were once when a dock worker removed my plug and did not twist it locked, and when i was at a marina with open ground----
try using plug correctly. it will prevent fires also.