AC Electrical outlet problem, wierd, but true

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rtrinkle's picture
rtrinkle
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AC Electrical outlet problem, wierd, but true

Alright, I've been working on electrical circuits 12 volt and 120 volt for many, many years, and have come up with a strange situation with an outlet and a light plugged into the specific outlet.

We have 2 AC lamps in the salon. One light is plugged into the starbard outlet by the starbard settee. However, this light will not work in this outlet, either the top or the bottom female outlets. However, move the lamp to the port side, and it works fine.

Here's where it gets tricky. The other items I plug into the suspected outlet work just fine (battery charger for additional 12 volt batteries, and a 29" flat screen TV).

The only thing I haven't tried is moving the port lamp to the starboard side to see if it works. [I actually just thought about doing this.]

Any ideas?

Robert Trinkle
Troubador, 1995 C36 MKII #1433, SR/WK
Universal M35A
Kinsale Harbor Marina
Kinsale, VA

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HowLin
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No ideas, but I'm sure waiting to hear the outcome... :D

---- Howard & Linda Matwick ----

--- S/V "Silhouette" - Nanaimo, BC ----

--- 1999  C36 MkII  #1776 M35BC ---

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plaineolde
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Does one have a green bulb in it and the other a red bulb? Port and starboard lights?

Sorry, couldn't resist.;)

That is odd; I'd take a close look at the prongs on the plug of the lamp that's giving you trouble. It's possible that they are bent slightly, just enough to not make contact in one outlet, while working fine in another. I've actually run into this sort of problem at home, particularly with a 2-prong plug, most recently on a vacuum cleaner.

Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay

Maine Sail
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Are the bulbs in the lamps polarity sensitive...

-Maine Sail
https://www.marinehowto.com/

 

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Steve Frost
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Polarity will not be the issue as we are talking about AC, Alternating Current.
We all know that A/C in the USA runs at 60 cycles per second. My guess is that you need to alternate these lamps port to starboard quicker.

No thanks needed, this is just what us technical advisors do.

Steve

Cepheus dream
C36 MK I # 825
MK I Tech Editor No Mas

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baysailor2000
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Posts: 218

plug in a powers strip that has a light on it indicating that 110VAC is available. Then insert your lamp into the power strip. If it works then replace the wall receptacle - it is worn out. Or - take a flat head screw driver and insert into the pins of the lamp and spread it a bit. It may not be making contact when plugged in.

Haro Bayandorian, 1999 C36 MKII, Sail La Vie #1787, M35B,
Coyote Point, San Mateo, CA.

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LCBrandt
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Reading about a weird symptom like this turns a BIG RED LIGHT On in my brain! Weird symptoms in electrical systems ALWAYS raise my suspicions regarding proper grounding. (See other posts I have made on this.) What you're describing should not happen, but apparently it is doing what you say. And this makes me question the integrity of the wiring of your AC system.

My suggestion is that (a) you take the lamps ashore see if they work as they should; and then (b) you absolutely verify that your boat wiring is correct, particularly the AC neutral versus the DC ground. IF you have a mis-wire in your AC system, you *may* unknowingly have all metal items in the boat at a high AC voltage - or - you *may* be allowing AC current into the water around your boat - or - some other serious risk may be present.

Please treat this odd issue with the utmost seriousness until you have it fully resolved/understood. The safety of your crew and others may depend on this.

Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
 

BudStreet
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Posts: 1127

Don't know about below the border, but up here everything 110VAC has a big terminal and a small terminal, and a ground. Which tells me that polarity is indeed significant. We had one plug that was different than the others visually and it also was installed upside down. It was really flaky at times especially with non-incandescent lights. I took it out to turn it over and saw it was also wired wrong. Reversed the wiring and it has been fine since. Certainly I'm no electrish but I dunno about polarity being a non issue.

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deising
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I took a moment to find this write-up on the Net. It may not be the best or most authoritative explanation, but for starters:

Polarity and Electrical Devices
■It used to be that polarity was not such a big concern, especially when using standard incandescent light bulbs with nothing more than a sealed vacuum enclosure with gas and a carbon wire filament which was not polarity sensitive, the light bulb would light if the power flowed in either direction, it just needed power to make the filament glow. With more modern electrical devices, we have a third wire for the ground and more and more devices have electrical circuits and components that are definitely polarity sensitive.
■You may even notice that one of the straight blades of the 120 volt outlets is larger that the other, and the same is true for the plugs found on many cords of electrical appliances. This is because there is a specific polarity that is needed for the specific circuit components.
■The hot wire of a 120 volt circuit is an ungrounded conductor while the neutral wire is a grounded conductor, both being current carrying conductors which is why they are insulated.
■The third wire being the ground wire may be uninsulated because it is a non-current carrying conductor which is used as an equipment safety which is attached to the frame or enclosure of the electrical device. This grounded conductor has a direct path of least resistance to the main ground source where it sends voltage in the case of a failure, which is designed to quickly cause the circuit protective device to trip and de-energize the circuit and protect it from damage.
■Some electronic devices may actually be damaged if they are plugged into an outlet that has reverse polarity. So to summarize this it is well to understand that with today’s electrical circuits it is best to make sure the polarity is correct

[url]http://www.ask-the-electrician.com/the-importance-of-electrical-circuit-...

[U]However, here is a quote from a marine electrician[/U]:

Some older boats with AC electrical systems installed by less than expert hands are fitted with single pole main breakers but not fitted with a polarity indicator light. You must also remember that even if your boat is wired correctly, the shorepower pedestal may not be.

So what happens if polarity is reversed ? If the polarity is reversed, then the neutral (the grounded conductor) is now powered by the hot (ungrounded conductor) line. All appliances and loads on the boat will still work since they don't care from which direction the alternating power comes from.

With proper polarity If a fault occurs in one of the loads (like a ground fault/short circuit) , the current will increase substantially on the hot line which should trigger the branch supply circuit breaker for the load to trip. That's the main purpose for having the ground system installed (to ensure there is a path for fault currents to go so that the current will become high enough to trip the breaker, at the same time keeping the voltage down on the exterior of the faulted component).

In a reverse polarity situation, when a ground fault occurs, the current rises substantially on the neutral line, If there is no breaker in the neutral line ( single pole), the conductor will heat up, cook, and could eventually cause a fire. That's why we have polarity indicators. They tell us there is no over current protection for the neutral conductors supplying power to loads.

[url]http://www.pcmarinesurveys.com/AC%20Polarity%20Indicator%20GFCI.htm[/url]

Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/

plaineolde's picture
plaineolde
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You can pick up an outlet tester at Radio Shack, Lowes, Home Depot or a hardware store. Plug it into the outlet and it will tell you whether the outlet is wired correctly.

I play in a band and learned to always check the outlets the first time we play a new venue. At one venue, one member of the band got a shock every time his lips touched the grill of his mic if he was touching his guitar strings. Plugging his amp into the same outlet as the PA solved that problem. I picked up an outlet tester and next time we played there I tested the outlet and found it to be wired backward. So there were potentially 110 volts (likely less) between the strings of the guitar and the mic grill. That doesn't feel good and is potentially deadly. Since both the guitar amp and PA have polarized plugs, if the outlets are properly wired, this danger is avoided. But not all buildings, particularly old ones, are wired correctly. The lamps on your boat may not have polarized plugs, since lamps will operate either way, but as mentioned in the prior post, other things do care, and/or can create a dangerous situation.

Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay

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Steve Frost
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Sorry to have made light of this (pun not intended) as 110 volts aboard can cause some very serious issues.

I still stand by my thought that the problem encountered would not be a polarity issue. As detailed by Duane Mis-wiring an A/C outlet can create many dangers but the failure seen with the incondecent light would be unlikely. If it sees a hot and a neutral or a ground it will work regardless of what way they are attached to the line. More complex electrical devises especially if grounded may not work if ground or neutral are swapped but not an incondecent lamp as it is not phase sensitive, the neutral is alternating -\+ sixty times a second through the resistance coil of the lamp.

A worn outlet as previously suggested is the most likely fault here. This should be a straight forward fix. If you are at all uncertain about working with A/C wiring, please get someone else to look at the issue, and have them explain what they are doing for your understanding 110 Volt can be deadly.

There are some subjects here that should not be made lite of do to inherent dangers involved, I guess we should put 110 volts on boats in this category.

Cepheus dream
C36 MK I # 825
MK I Tech Editor No Mas

deising's picture
deising
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My first reaction was agreement with Steve that "polarity" should mean nothing to a resistive load like an incandescent lamp, and it does appear that except for one statement about "certain electronic devices" that all the concerns regard safety, not functionality.

I have not found any other definitive discussion on 'why' A/C voltage should matter to any device since as Steve has pointed out, the current reverses at 60Hz anyway (at least in the USA).

Hoping we get a report on the root cause.

Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/

rtrinkle's picture
rtrinkle
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Posts: 203

Alrighty,, there is alot of good info here. The light did work for several months before it decided not to work. As the light normally on the starboard side works on the port side outlet, I don't think its a light prong problem,, but I will check. Since other items (TV and battery charger) work in th the starboard outlet with no problems, I suspect the outlet and wiring is fine.

However, given the advise here, I will slightly bend the prongs on the light. I have an outlet tester, so I will take that as well on my next trip this weekend. And for safety concerns, I will check the wiring and ensure I'm not getting any voltage to ground,, but the light was working before, and still works on the portside. I will also take some extra light bulbs and check that. I have seen light bulbs that had issues when first bought. I'll be sure to take red and green lights.

Perhaps Troubador is playing a trick on me. We have had some pretty bad issues found and resolved after the fact (our engine was out of alignment b/c the stringers were rotted out (the issue was not found by the surveyor)), and she protected us.

If anyone has further advise, it would be greatly appreciated.

Robert Trinkle
Troubador, 1995 C36 MKII #1433, SR/WK
Universal M35A
Kinsale Harbor Marina
Kinsale, VA

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rtrinkle
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Posts: 203

To everyone's concern,, the problem is resolved. In my years of electical work, sometimes I feel I need to get back to the basics. It appears the lightbulb I replaced was bad. I put another light bulb in the light, and all is working fine.

Thanks again for all the great feedback.

Robert Trinkle
Troubador, 1995 C36 MKII #1433, SR/WK
Universal M35A
Kinsale Harbor Marina
Kinsale, VA

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