H27 Polarity Indicator problem

[tcrespo]

For the last 12 months I've had an issue with the shorepower. Everything seems to work well, but any high startup load devices (Shop Vac, AC unit) would cause the 15 Amp dock circuit to blow. After figuring out that I could run these devices directly back to the dock and they would work fine, I started narrowing things down.

This weekend, I decided to disconnect the reverse polarity indicator (after hearing a strange noise the last time the circuit blew). Once I removed it, everything works great. I had the AC, fans, microwave and a computer all running on the boat with no issues.

My question is this - I'm on a lake, always at the same dock - how important is this polarity indicator? The boat has been at this marina (on various docks with prior owners) for over 10 years. I am confident that the power supplied to the boat is good and pure.

Do I need to replace this unit, or can I just go without it?

Thanks in advance for any assistance (and don't worry Ross - I'll be checking back throughout the day for replies)!...

Tom

 

[Ross]

I ain't worried about you and that concern .;D

Buy a plug-in polarity checker and use that. You can even get them that check GFCI breakers. About 10-15 bucks.

 

[GuyT]

I dont see the connection

between an indicator that should draw no current and tripping a breaker.
Maybe you fixed the problem by simply tightening things down when you removed the indicator - I have seen problems fix themselves just by removing and re-installing. Connections are always issues on boats. Try re-installing the indicator and see if the problem comes back.

Anyway, if it is bad I would replace it. In the event you ever sell the boat or change docks - you never know.
Reverse polarity can be very dangerous - I would want to know about it.

 

[tcrespo]

Checking today

I'll check it today with a tester and also try reconnecting it. Thanks! Tom

 

[Don12364]

Varistor?

Hi tcrespco. I think you are referring to the installed varistor as the reverse polarity indicator. Hunters fit these between the neutral and earth on the shore power wiring. Normally they represent a high resistance and have no effect on the power supply but, as soon as the neutral has some voltage on it (as when the shore power polarity is reversed), then this device conducts electricity and trips the ground fault breaker.
In fact the reverse polarity indicator is the small neon lamp which lights up on the panel.
The system will run without this varistor connected but it then will not trip the breaker automatically so you might have a reverse connection and not know unless you monitor the neon lamp - normally only necessarily when first connecting to the shore supply.
From the symptoms described it would appear that there is a substantial voltage drop down your dock wiring from the ground point ashore. This may be nothing to do with yourself and other boats may be contributing to this. I suggest you measure the voltage difference between neutral and ground on your boat whilst you are running a known load and if it is more than a few volts have a word with the dock staff.
Whilst about it also measure the voltage arriving on board both off load and on load. You may be surprised.
Presumably your shore power lead is okay?
Caution:- From your description you appear to be competent to work on live wiring but if you have any doubts whatsoever than get a competent electrician to do this.

 

[tcrespo]

Label

Donalex - thanks for the response. The device in question has an actual label on it that says "Reverse Polarity Indicator". I had done a search on the threads and noted that people kept mentioning an indicator light on their panel. My 78 27 has the original hunter panel in it but no lights on it.

The device (we'll call it that for now) has two wires that come out of it - it's mounted right next to the shore power connector up underneath the rear quarter berth. The two wires go to the hot and neutral of the connector - nothing to the ground.

Haven't gotten a chance to check the dock polarity yet - hoping to do that by this weekend. We had a tremendous amount of rain here yesterday (thank goodness - drought has been horrible - got 8 inches yesterday alone thanks to the remants of TS Fay), so I've been in batten down the hatches mode versus diagnostic mode.

Will report back soon - again, thanks for the info!

Tom

 

[Don12364]

Puzzled

Am puzzled as to what type of component is fitted to your boat. Because there is no light (or other visible sign?) it seems unlikely it can be an "indicator" despite the label. Having only two wires and connected between hot and neutral, and with no connection to ground I do not see how it can determine when the polarity of hot/neutral is actually reversed.
To me this is where I would expect to find the Ground Fault Interrupter and, in view of the fact that it is adjacent to and wired to the shore power inlet socket, I wonder if this is what is fitted - despite the label? Also this might not have a ground connection to it either. My boat has a breaker here too.
For my info is this a sizable item or just a small component?
I attach a picture of a varistor similar to that used by Hunter in recent years. It measures about 1/2" in diameter. Please disregard the colour as they come in all shades and also ignore the markings as I just selected a picture from a catalogue.

 

[Jim]

Ross is on the right track

I would also get as isolation transformer. It is worth the money!

 

[Jim]

Varistor

MOV, Metal Oxide Varistor are a high impedenace resister under normal votage but become very low resistance under high voltage. When the are placed in shunt with the load then protect it from a high voltage strike. I am not an expert but would have to say, you don't need it. I would get the isolation transformer if you don't have one.

 

[Jim]

I 100% agree with Donalex from England

there is a substantial voltage drop somewhere in your system. You should be able to see this with an ohm meter. I would guess it is close the the shore power outlet. I would try someones shore power cable first. The check you shore power boat plug.

 

[Frenchie3958]

VARISTOR and Surges

We use Varistor on our machines to protect the power supply BUT when a huge surge occurs these nice componants become in 50% of cases a real SHORT CIRCUIT (they blow up),the main breaker blows and we have to replace them. DONALEX show you a picture of a new varistor, they can be blue,red or yellow but when they turn dark and explose in pieces in case of dammage. JIM gave you the best advice use an insulation transformer !!

 

[tcrespo]

Update

Finally got to the boat and was able to check polarity - it's fine all the way through the dock circuit and into the boat.

I should add that all of the A/C wiring in the boat (including the GFI, wiring and outlets) is also all new. The only "old" components are the actual shore power recepticle and the mystery device.

So - the mystery device - it's about the size of a transformer pack (like you'd use on your laptop). It has two wires that come out of it and go to the shore power connector - one to neutral, one to hot. The label on it says "Reverse Polarity Indicator."

I'll be out for a labor day sail tomorrow and will snap a picture of it.

I can say this - without that thing attached, the electrical system on the boat has never operated better. I'm no longer tripping the GFI on the dock and I can run everything with no issues.

I should also add that prior to the disconnect of the device, the dock circuit would also blow when other people used high current devices. Early in the summer, two slips down, a guy moved in and put in a lift, the type that sounds like a vacuum cleaner. Anyway, whenever he'd fire that thing up, the dock circuit would trip. The interesting thing is that unless I reset the breaker on my boat, the GFI on the dock would not reset (they would end up unplugging my boat so that they could reset the GFI). With my boat disconnected, the lift worked fine.

Today when I was there, I asked Brad (the guy with the lift) to give it try. I had all sorts of things on my boat running - radio, fans, etc. He fired up his lift with no problem and nothing tripped.

Again - picture of the mystery device will be posted by tomorrow night.

Tom

 

[tcrespo]

Raritan Sonic Polarity Indicator

Green in color - mounted up under the rear quarter berth. Do I really need this thing? Boat electrical system is working great without it!

Thanks - Tom