What is this porcelain gizmo on my breaker panel?

[photomikey2]

See attached photos - this porcelain gizmo attached to my 2x20amp breaker panel - what is it? Has a couple red wires coming out of the back.

[RivetED]

Someone might recognize it but your both photos are too far out of focus for me to clearly see it. A wild guess is it may be a rheostat.

[Bubba L]

It’s mounted on the top of the breaker box with a small bulb and wired in the box. I don’t remember if it stays lit when there’s power to the box or lights up when the shore power has an issue with polarity.

[FenderBender]

It's a polarity indicator. Lets you know if your trailer is plugged into shore power correctly.

[OTRA15]

Welcome to the forum.

Do you have the printed manual? On the lower right corner of p. 11-1 of this one, for a 1964 Overlander 26' Twin, it confirms this is a polarity indicator light, which should be off if the shore power is working correctly. [PDF p. 63/78]

https://www.airstream.com/wp-content...s-book-423.pdf

[photomikey2]

Indeed, it is a polarity indicator. One pole attached to the trailer body, one pole attached to the ground bus bar in the panel. It would illuminate if reverse polarity.

I'm actually not new to the forums, I've been here a decade or so. At some point we switched over to "RVLife" and apparently my old name (photomikey) is lost to time.

[OTRA15]

Welcome back!

Here is your last thread from early 2020:

https://www.airforums.com/forums/f45...ng-205305.html

By clicking on your user name on the left side of a post, you can "Find More Posts" in the drop-down menu.

Have fun with the new Overlander.

Peter

[Streamracer]

As kind of a side note has anyone noticed how OTRA15 can whiz around and find information from nowhere on the forms and post links?Great job Peter.

[OTRA15]

Thanks . . . a bored retired old guy with too much spare time?

[PatLee]

Streamracer - I was thinking the EXACT same thing about OTRA15's uncanny ability to methodically, uncritically direct people to where they need to go.

[OTRA15]

Thanks.

[Wazbro]

Originally Posted by photomikey2

Indeed, it is a polarity indicator. One pole attached to the trailer body, one pole attached to the ground bus bar in the panel. It would illuminate if reverse polarity.

I'm actually not new to the forums, I've been here a decade or so. At some point we switched over to "RVLife" and apparently my old name (photomikey) is lost to time.

Yes and if your trailer is plugged into an outlet with reversed polarity the shell would now be carrying a small electric charge and shock you if you touch it when you are grounded. Shouldn't be dangerous for a healthy adult, watch out for pets and people with pacemakers or other electronics surgically installed.

[Outbackga]

That is true only if the neutral (white) is INCORRECTLY bonded to the trailer frame. Unlike stationary house wiring, neutral is NEVER bonded (connected) to the trailer frame . Only the green/yellow wire should connect to the trailer frame.
I also disagree that the shock is harmless, it can be fatal. Do not ignore this issue if it occurs.

[gator.bigfoot]

Too bad they don't include those anymore. Would have helped some folks. We include them on all our electrical panels that we build.

[OTRA15]

Thanks for this:

Originally Posted by gator.bigfoot

Too bad they don't include those anymore. Would have helped some folks. We include them on all our electrical panels that we build.

We leave the following inexpensive polarity indicator plugged into the 120-volt shore power outlet above the fridge:

https://www.amazon.com/Power-Gear-Re...5838104&sr=8-2

. . . where it is visible from most of the trailer, as well as through the dinette window right after connecting shore power.

Does this device do the same thing, as that old AS OEM light, in effect?

Thanks,

Peter

PS -- And don't the Progressive EMS devices perform a similar polarity test internally?

[Oreg52]

Originally Posted by OTRA15

Thanks for this:
We leave the following inexpensive polarity indicator plugged into the 120-volt shore power outlet above the fridge:

https://www.amazon.com/Power-Gear-Re...5838104&sr=8-2

. . . where it is visible from most of the trailer, as well as through the dinette window right after connecting shore power.

Does this device do the same thing, as that old AS OEM light, in effect?

Thanks,

Peter

PS -- And don't the Progressive EMS devices perform a similar polarity test internally?

I have something similar. I plugged it into the outlet next to the door. Easy to check when entering the trailer.

[Wazbro]

Originally Posted by Outbackga

That is true only if the neutral (white) is INCORRECTLY bonded to the trailer frame. Unlike stationary house wiring, neutral is NEVER bonded (connected) to the trailer frame . Only the green/yellow wire should connect to the trailer frame.
I also disagree that the shock is harmless, it can be fatal. Do not ignore this issue if it occurs.

Not what I said. The reverse polarity light would connect a small charge (through the light so only a few watts) from the neutral line to the ground, this amount of current would be fairly harmless to most healthy adults. IF you search well enough you can find a couple threads about someone kneeling, sitting or laying on the ground and touching their trailer and feeling a tingle that was traced back to a reverse polarity light.

If the neutral and ground were bonded with the polarity reversed yes that would be dangerous to anyone.