Reverse Polarity

[BobP]

Then he can get the pocket tester at sears and plug it in every oultet, and read the color coded LEDs to anwser teh question. Anybody can do that.

 

[Grog]

There is no reason that a GFCI will not worked when plugged into another GFCI. Many large services have GFCI protection on the Main (for equipment set to trip at about 30 milliamp imbalance) and then standard GFCI's on the branch circuit. The only problem with multiple GFCI's is that when they trip they must be reset in sequence (upstream GFCI's must be reset before downstream GFCI's can be reset) and this causes confusion.

The new GFCI's may have changed but the older models would not function if you wire a GFCI to a GFCI, the older models don't need power to reset. You can't lump a large service ground fault in the same category as an outlet GFCI. A 30 mA trip would be worn out in a week at most factories. I've seen larger services trip and some not trip (idiot drilled into a MCC bucket and hit a bussbar and it saved his but, another tightened a #10 wire on a starter and blew the whole bucket out, he didn't work for a year).

 

[ahill]

BobP,
I'll check the panel mfr. and let you know.
The problem isn't with a GFI just a glowing rev pol light. It gets brighter when the charger breaker is energized.

 

[BobP]

That's interesting, about the charger breaker being closed and the reverse polarity light getting brighter.

Irrespective of what panel mfg says, go to Sears and get one of those pocket testers for checking wall outlets, it has some LEDs on them and a color code indicating if the outlet is wired properly (wpould also indicate of upstream problem all the same), I bought one 20 yrs ago for about 10 bucks. Plug into every receptable on boat, GFCI or not, an read colors.

I have to think about why charger would effect light

 

[haskindm]

[/quote]The new GFCI's may have changed but the older models would not function if you wire a GFCI to a GFCI, the older models don't need power to reset. You can't lump a large service ground fault in the same category as an outlet GFCI. A 30 mA trip would be worn out in a week at most factories. I've seen larger services trip and some not trip (idiot drilled into a MCC bucket and hit a bussbar and it saved his but, another tightened a #10 wire on a starter and blew the whole bucket out, he didn't work for a year).[/quote]

I am sorry but you are misinformed. There is nothing in a GFCI that will cause it to trip if connected to another GFCI. They are simply CT's that measure current imbalance between the hot and neutral (or between the two hots in a 240-volt GFCI). If there is no imbalance there is no trip and connecting one GFCI to another will not cause an imbalance. Most new hairdryers come with GFCI protection built in to the cord, these can be plugged into a GFCI protected outlet with no problem. All GFCI's require power before they can be reset, this was true when they were introduced in the 70's and is still true today. The difference in the new GFCI's is that when/if the electronics fail they must be de-energized or have an indicator light that shows that the GFCI circuitry is no longer functioning. 215.10 in the National Electric Code requires GFCI protection on any disconnect rated 1000-amps or more where the voltage to ground exceeds 150, so a 1000-amp disconnect on a 480/277-volt system requires GFCI protection. The following is from Siemens company:

Ground fault protection for equipment
must open a circuit when ground fault current reaches 30
milliamps. Health care facilities, such as hospitals, require
additional ground fault protection. This is outlined in NEC®
Article 517.17.

 

[Grog]

PM sent

 

[ahill]

I emailed Blue Sea.
As a refresher, the shorepower was installed by Grady dealer. The reverse polarity does not glow on direct shorepower only on generator. I have no problem with gfi"s.

 

[ahill]

Blue Sea's response
Dear Sir,



Thank you for your inquiry. What you are likely experiencing is the result of voltage drop in a long wire run which increases as loads are turned on. A full discussion of what causes this phenomenon can be found here: http://bluesea.com/viewresource/85. The red LED only consumes 5 mA at full brightness, so it is somewhat less than that given the brightness you are seeing. Since what we are measuring is the potential for current in the neutral leg, a simple test to see what's going on is to measure the voltage between the neutral and safety ground leg. If you have a true reverse polarity situation, then the voltage will be in the neighborhood of 120.



Best regards,



Scott McEniry

Sales Operations Manager/Sales Engineer

Blue Sea Systems

 

[BobP]

Thanks, this is what I expected in how it works, generally, and the test was covered by Jehines in a prior post, I believe. I wished the manuf. was more specific to explain changes when the charger is on, or via the generator, etc. Their legal dept. probably limits how much they can say.

The long lengths of wire do not apply in your case. The lengths in our boats are very short to begin with, but could be teh equivalnet of a bad/loose joint.

Nonetheless, if you are confident and have a mulitimeter and can measure the voltage as indicated, then fine.

You can alternately google "outlet tester", and pick one up and plug it into any outlet.

I was thinking about the charger scenario, the charger output shouldn't matter on the pos & neg how the input is connected polarity wise on the AC - should it be miswired (it matter for safety reasons however). If the charger is defective and emitting too much AC riding on the DC, and with the DC ground connected to AC ground / neutral, who knows what that can do ? And/or the charger may not like generator power quality.

You say when the charger is on, the light gets brigther, lift the charger dc leads off the batteries, then turn on the charger breaker and see what the light does. Tape the leads so they contact nothing when disconnected.

 

[ahill]

I connect through a shore power cable 25' with a pigtail to 3 prong. Maybe that's it. It still could be caused by inverter or generator ground.
I'll try a shorter run. What if I connect dynaplate to ground screw on generator?

 

[BobP]

You have to measure (or have measure for you) the voltages to verify the state first.

And 25 ft isn't long, if it was 500 ft, that's long!