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Check Your Shore Power Plug & Power Center Connections Regularly!


lb311

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I've been RVing for 10 years and full-timing for almost 2, but last month I nearly started my rig on fire due to my RV's 110 electrical system going haywire.

 

My problems started one night last month with circuit breakers flipping when I was running my ceramic heater. I'd been running the heater fine for weeks and my RV is currently parked for the season, so nothing had changed from the day before. Once I reset the breaker the 3rd time, things seemed to work o.k. again, but within a few days I started noticing a slight smokey smell whenever I was running a "high-demand" electrical appliance (i.e. space heater, microwave, hair dryer, etc). The appliances continued to work so I didn't immediately investigate the problem. But a few days later when I finally did, oh good heavens!

Opening the access panel of my power center/converter revealed some severely charred 110 wiring (all of my neutral buss wires were burnt to a crisp!). I stopped using 110 electric immediately, and the next day, the park's electrician came to check my outside power pedestal for any miswiring or other problems. It checked out fine, so the problem was deemed with my RV. The electrician suggested I start troubleshooting from my surge protector all the way to my power center/converter to look for loose or faulty wires.

 

Long story short, I discovered that the wiring inside my shore power plug had become faulty due to one of the screw posts rubbing against the ground wire's insulation until it finally wore thru. This created a "hot neutral" condition which then burned up the neutral buss wires in my power center as well as the neutral prong receptacle of my surge protector (that the shore power plug was plugged into).

 

So my tip to all fellow RVers is to inspect your shore power plug regularly (at least annually), and routinely double-check all your power center wiring (and any other RV wiring you can easily access) for any loose connections as well.

 

I thought my fancy $200+ surge protector would keep my rig safe from any and all electrical problems. Nope! It can't prevent the RV-side electrical problems, it only protects you from those lurking at the power pedestal! I learned a valuable lesson...and dodged a major bullet by getting this fixed before a fire started!

If you're interested in further details and photos of my saga... check out my blog posts here and here.

 

Lynne

 

 

 

 

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If that were the case I think the breaker on the pedestal would have tripped. I think your problem was just loose connections on the neutral return leg from overloading. I had the same problem in a transfer switch once.

 

Looking at your picture that is just overloading. The neutral and ground are generally bonded in the panel. That is a lot of current coming back on the neutral leg.

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Ranger Smith,

 

When you state "The neutral and ground are generally bonded in the panel" I trust you mean in the RV parks power distribution system NOT in the RV's AC Power Distribution Panel???? FYI There's only ONE Neutral to Ground Bond, its NOT bonded again in the RV panel.

 

John T

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Between the story here and what I saw on her blog, I think Lynn needs to get the help of someone who is qualified to do 120V electrical work. I once read a paper from the insurance industry that said that amateur electrical work was the #1 cause of RV fire claims.

 

But it is important to check your power cords and plugs on a frequent basis. And be careful with the use of extension cords as well.

 

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Kirk, in addition to "I once read a paper from the insurance industry that said that amateur electrical work was the #1 cause of RV fire claims."

 

I'm also amazed and afraid (even in relatively expensive units) of how so much wiring is wire nut connected maybe NOT inside protective enclosures and tucked up inside or against thin easily flammable pressed wood or super thin plywood and all other sort of tinder. Many RV's are built so cheap and fast and you see those crimp on or push tab connections YIKES especially where 1500 watt heaters are in use!!!!!!!!!!!!!!!!!! Many of those combination Converter/Charger and AC and DC distribution systems and panels are UNDER THE BED...........Proper fusing,,,,,,,,,,,,,,good regularly checked and tightened electrical connections,,,,,,,,,,,,good working smoke and LP gas and CO detectors,,,,,,,,,,,,,plus a good "smeller" and plenty of fire extinguishers handy ARE ALL A SAFETY MUST

 

I'm NOT saying I never use a 1500 watt cube space heater in an RV, but I still don't feel that's the safest thing out there subject to the RV wiring and how and where its connected.

 

I wonder in the future or already for all I know the RV industry will go to Arc Fault protection in addition got GFCI??? Arc Fault will detect those low (not enough to trip the 15 amp breaker) current yet still extreme heat producing shorting buzzing arcs like a cheap pinched extension cord can produce. I see them as even MORE important in a thin wood RV then a persons home.

 

Lynn B, keep safe now and best wishes

 

Oh well, keep safe yall and Merry Christmas

 

John T

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From her photos and blog, it was a neutral to ground short, not a hot to ground short. I find that baffling as a cause of the problem UNLESS the outlet or elsewhere is reverse wired. The neutral and ground are bonded together at the park panel anyway, so there should be no current flow between the two at the RV end. I think I'd start by verifying that the park outlet is not reversed.

 

On edit: Another possible cause would be a bad neutral on the park side, causing the full load to be using the poor short to ground connection as the neutral. In either case, the plug design was not the cause of the problem, as a neutral/ground short should not normally cause any problems by itself.

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Mornin Dutch, to your statement "it was a neutral to ground short, not a hot to ground short. I find that baffling as a cause of the problem UNLESS the outlet or elsewhere is reverse wired."

 

My thoughts are if indeed in the RV panel there was a Neutral to Ground short (one pic looks like the green may be shorted to Neutral Buss???) a parallel current path is created (Neutral and Ground) and if balanced each conductor carries only HALF the return current which reduces current and heating IE less heat in either the Neutral or Ground from short back to parks power pedestal. Like you I don't see that as causing all that damage.

 

HOWEVER, Again like you, if at the RV panel the Ground got shorted to a Hot conductor (perhaps reverse wiring) NOW THATS SOME BIG TIME HEAT AND CURRENT some of which might find alternative paths and other wires got overheated.

 

Same in the RV plug, if ground were shorted to Neutral that's one thing, but if Ground were shorted to HOT big time heating and burning until a breaker cleared the fault or it burned itself open.

 

Something for sure went wrong and high currents caused all that melting............

 

John T

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Mornin Dutch, to your statement "it was a neutral to ground short, not a hot to ground short. I find that baffling as a cause of the problem UNLESS the outlet or elsewhere is reverse wired."......................................

Something for sure went wrong and high currents caused all that melting............

Which is exactly the reason that I suggest Lynn needs some qualified help. The explanations she gives are not supported by electrical theory.

I would also comment to other readers to be very wary of electrical advice you find on the internet when you don't know anything of the author's qualifications for giving technical advice.

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Which is exactly the reason that I suggest Lynn needs some qualified help. The explanations she gives are not supported by electrical theory.

I would also comment to other readers to be very wary of electrical advice you find on the internet when you don't know anything of the author's qualifications for giving technical advice.

 

I fully agree, Kirk...

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Boy-- lots of testosterone on this board. Guess you guys have never heard of a female actually replacing her own RV power center and living to tell about it. Unbelieveable.

 

Kirk, the photo you posted above has absolutely zero to do with my RV electrical system-- that's an outdoor extension cord hooked up to a completely separate 20 amp outlet that connects a water hose heat tape and a temp-controlled plug for a utility light that heats my water bay. I'm sure you would have, no doubt, come up with a much nicer looking solution, but stowing mine inside a concrete block, keeps them above ground and dry.

 

I did indeed confer with 2 qualified RV electricians before undertaking this job, but as I am at a Wildlife Refuge 120 miles from any repair shop, I had to do this repair myself if I wanted it done quickly. I was not some ditzy dame with no electrical familiarity! The RV electricians assured me that the job was nothing more than cutting and stripping wires and reconnecting them to the new power center, and that was something I was fully capable of doing myself. A licensed electrician for the Refuge also fully inspected the pedestal for any miswiring or voltage issues-- I watched him do it.

 

The new power center and shore plug have been running now for a month and show no signs of miswiring, melting or other calamity. Yes, it actually works, as hard as that might be for you guys to imagine.

 

I did not post this looking for critiques from the peanut gallery. I was sharing my story to raise awareness so that other RVers will remember to inspect their electrical connections annually.

 

Mine was caused by a bad shore power plug that allowed some movement/chaffing of the ground wire behind the neutral screw post over time. The plug base was missing part of its clamp when I bought the RV a few years ago, but I never thought to open up and inspect the connections as I never knew this was something that should be done routinely. Now I know! Just wanting other RVers to learn this step too.

 

Lynne

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Lynne - It is recommended that connections be checked on an annual basis. Cord, Marinco plug if you have it, panels, breakers, basically all connections. According to the breaker manufactures, it is also recommended that you "exercise" (open and close) all your circuit breakers monthly (this is in case any internal contacts get stuck together).

 

Gender does not play a part in this. I have worked with good/bad electricians of both genders. Attention to detail is usually the best factor of good and bad.

 

When outside, I also try to raise the cord connections off the ground, usually I use a bucket or plastic milk crate. The cinder block is better than on the ground but it is abrasive on the cords. You use what you have and the block is better than the mud, but those edges are sharp. An old piece of hose, split down the center will mechanically protect the cords.

 

Have a great day.

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Boy-- lots of testosterone on this board.

 

reconnecting them to the new power center, and that was something I was fully capable of doing myself.

Mine was caused by a bad shore power plug

 

Lynne, in the posts I read, no one had inferred that you were not capable, but that there was another issue in play that undoubtedly was resolved by installing a new power distribution panel. You hadn't mentioned that you had already done that which was why some were suggesting an electrician to diagnose the actual problem in the original panel.

 

From the photo and description you gave, what 'is' clear, is that the ground to neutral (a hot to neutral fault in the plug would not have been possible from the photo that you showed) in your plug was NOT the contributing factor but a 'result' of the actual hot to ground/neutral that was likely occurring somewhere in your panel.

 

You solved the "cause" by replacing the panel and repaired the subsequent damage to your plug.

 

Reminding folks to regularly check all connections and electrical cords though DOES have merit!

 

All is well with the world so let's not forget to go have some fun. ;)

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I've found the posters here to be polite and professional and NOT biased. We try our best to help and I for one am NOT here to fight or disrespect anyone, male or female.

 

That being said, FWIW I, a retired AC Power Distribution Design Engineer, BSEE Purdue University, 40 years experienced, am of the polite with all due respect professional opinion, a short in the RV Plug WAS NOT ALONE THE SOLE CAUSE OF ALL THAT BURNED WIRING INSIDE THE RV PANEL. A Hot to Ground short in the plug would burn the wire open and/or trip the circuit breaker. A Neutral to Ground short there would NOT trip the breaker and NOT alone burn the panel as shown in the picture if all else is okay.

 

HOWEVER if a Hot Ungrounded live Conductor in the RV somehow somewhere got shorted to that Green Equipment Grounding Conductor, which is possible if the Ground got shorted to what was supposed to be the Neutral, but wires were somewhere (could be a lot of places I cant say where) reversed, NOW THAT COULD CAUSE THOSE BURNED WIRES.

 

That's my story and Ima stickin to it lol but mean no disrespect or want to argue or discriminate on the basis of ethnicity or gender. That opinion was NOT based on anything other then my education and experience as a professional Electrical Engineer. Feel free to take or leave my opinion at your own risk and wishes, Ive been wrong before and will be again, but believe in my heart of hearts this is correct or else I wouldn't post it...............

 

So God Bless all here and best wishes and Merry Christmas

 

John T BSEE, JD Electrical Engineer and Attorney at Law

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ok, my apologies guys. I see what you're saying, and now that I've thought it through, realize that some other factor in the shore plug wiring or power center must have caused the hot neutral event (and that the burned up neutral/ground in the shore power plug was a result rather than a cause).

 

Sorry I didn't mention in the post above that I replaced both the power center and all the circuit breakers when I did this fix (that info was in the blog posts). So, it sounds like either perhaps I overlooked a hot to ground short somewhere in the shore power plug (that I managed to fix when I trimmed the wiring back and replaced the plug), or perhaps a bad circuit breaker inside the distribution panel managed to cause the short? (I never knew about exercising them monthly, thanks for the tip Bill B!).

 

John T-- could a bad circuit breaker have caused a hot ungrounded live to short the grounding conductor? When I inspected/repaired all the wires in the panel, the only ones with visible damage were the neutrals and a few of the grounds (including the heavy gauge green grounding wire). I could find no visible damage to any of the hot (black) wires running to the CBs, nor could I find any damage in the wiring behind the panel or at the junction box (where the shore cord terminates).

 

Otherwise, I'm not quite sure how I managed to unknowingly fix the hot neutral, but everything is now working as it should, and everything that I've been able to check in the RV has tested out fine for correct polarity.

 

thanks for the feedback,

 

Lynne

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Lynn B,

 

No apologies necessary, to tell the truth when I read your post I didn't even look at the picture and have male friends named Lynn (I dont know spelling differences lol) and I didn't even know your gender, plus at my age I don't have much testosterone left lol

 

Thanks for the feedback. The circuit breaker and its mechanical components and its two connections (Panelboard Buss and Output wire terminal) only connect Hot Buss in to Hot wire terminal out and the Hot BUSS has a serious high voltage withstand rating and is well physically separated from the metal tub frame, so NO I don't envision a bad breaker causing the problem. The more common breaker problem is they trip too easy or the mechanics doesnt let them cam over and hold in, after all they are spring and latch and cam mechanisms and not nearly as reliable as an old fashioned no moving parts piece of wire that melts under excess current IE a fuse.

 

The reason I suspect a Hot had to get to Ground or a Hot (due to a reversed wire somewhere) disguised as a Neutral got to Ground somewhere in the panel is it took a BUNCH of current to melt all those wires and in such a case that much current will seek every path it can find which must have included allllllllllllll those wires as they were alllllllllllll parallel current paths. Regardless if a Ground to Neutral (not much affect) or Ground to Hot short (serious wire burning and open) in the plug, those current flows would be between the plug and the parks power pedestal and not in the panel.

 

I cant tell from the picture if the Green ground wire actually shorted and was in contact with the Neutral (white wires) Buss?????????????

 

Ya know if the RV Plug orrrrrrrrrrrr the RV pedestal outlet (or elsewhere for that matter) had Hot and Neutral reversed (easy to do) and that Green Ground wire in your panel was actually shorted to what was supposed to be the Neutral Buss, but was a Hot, THATS SUPER HIGH CURRENT which is super high heat causing melting.

 

There are several electrical sparkies here (Im rusty on this stuff) who have helped me before and sharper then myself, but I try to help best I can. However when others also agreed there had to be a Hot to Ground short to cause all that damage and that a Ground to Neutral short couldn't have been the cause I SURE FELT MORE CONFIDENT LOL As you probably know the Ground and Neutral are bonded together at the main distribution panel and are at near the same potential so their downstream shorting (like in your Plug or elsewhere) does NOT cause much current flow. HOWEVER its a serious code violation and a safety hazard if a second downstream bond or short exists. The Neutral is a Grounded Conductor that carries normal return current while the sole purpose of the Equipment Grounding Conductor is to provide a dedicated low impedance return path ONLY FOR FAULT CURRENT. The equipment ground is bonded to the RV metal frame and the outer conductive metal case/frame of some tools and appliances and you touch those SO YOU DONT WANT THOSE TO BE LIVE CURRENT CARRIERS NOW DO YOU

 

Nuff said (the others already know why I so long winded lol)

 

John T

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Lynne - I would suspect 2 things. Your MH should be seen as a large appliance on a cord. In the normal world (no problems) your ground wire comes into (via ground prong) the box as a single wire (electrically) to the ground buss and then through the MH to the ground connections on the plug(s). It should never have power or current until---- something goes wrong. It is a safety path that is NOT you.

 

The cord cap may have been -- dirty, sand, loose contact in the receptacle and I would still have the park pedestal checked for tension. This is one problem.

 

The second is / was your neutral, which you correctly repaired by replacement. And your right, they bolts / screws should be checked annually or sooner. Breakers work on heat. A bimetal strip inside heats up as power goes through it. Ambient heat or cold will effect it characteristics. If you had (probably) loose set screws on the neutral buss, they would have raised the panel internal heat and caused the several trippings that you had.

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Hi Lynne -

 

Looking at your blog pictures, it looks like the problem was one or more loose or corroded connections on the neutral buss inside the power center.

 

When you draw current through a bad connection, heat is produced. More current = more heat at the bad connection, so the problem only showed up under prolonged heavy current draw, such as running an electric heater for several hours.

 

The neutral buss sits pretty much in free air, the plastic insulator it sits on isolates it from the heat sink of the power center frame so any heat produced along the buss will heat up the buss and it's connected wires instead of dissipating into the wall of the power center. This amount of buss heating is less likely to occur in a stick home's main panel because it's neutral buss has a solid metal connection to the panel's frame, allowing it to dissipate heat to the frame instead of burning the other wires.

 

If you look at the burned wires, the greatest damage is at the two wires at the center of the buss along with possibly another wire at the bottom. I'll bet one of these come from the circuit feeding your heater and the other is the wire from the power cord. These are the wires that carry the heavy heater current. The rest of the burned wires were merely along for the ride, over time the heat from the loose connection(s) on the current carrying wires heated the rest of the neutral buss and transferred to the other burned wires.

 

Again, notice the wires towards the top end of the buss are burned less than the ones in the middle. The other thing that supports the buss overheating is the plastic insulator holding the buss in place is melted more at the bottom than at the top, but it's still insulating the buss from the metal case.

 

As far as the shore power plug goes, it looks like the neutral contact in the plug made a bad connection with the surge suppressor socket and heated up when you drew the heavy current. Notice the majority of heat damage is in the socket, indicating that's where the heat was centered. The screw melting the insulation on the on the ground wire is only collateral damage, it heated up with the rest of the neutral pin and has nothing to do with the original problem. Same thing with the white and ground wires fusing together - the white wire's insulation heated up and melted into the adjacent green wire's insulation. I'll bet the two wires are still electrically isolated from each other.

 

So you actually had two unrelated events exasperated by the prolonged heavy current draw from the heater - one or more loose connections on the neutral buss overheated, transferring heat to the other wires on the buss and burning their insulation. And a bad connection between the neutral pin on the shore power plug and the matching socket on the surge protector created enough heat to let the screw on the male pin melt the insulation on the ground wire and fuse the insulation between the white and green wires.

 

If you haven't already, you should replace the socket on the surge suppressor.

 

I hope this rather drawn out explanation helps, it looks like you did a good job repairing the damage.

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Kirk, the photo you posted above has absolutely zero to do with my RV electrical system-- that's an outdoor extension cord hooked up to a completely separate 20 amp outlet that connects a water hose heat tape and a temp-controlled plug for a utility light that heats my water bay. I'm sure you would have, no doubt, come up with a much nicer looking solution, but stowing mine inside a concrete block, keeps them above ground and dry.

My comment has noting at all to do with your gender. One of the best electricians that I have ever known is a lady and before I retired I worked with several excellent lady technicians. But they all had training in electrical theory and electrical safety. Electrical mistakes can be dangerous.

 

The extension cord was a side comment, added because of that picture since cords can easily be overloaded. I will say that you did use good judgment in the placement of that cord to partially protect it from weather, but excessive use of extension cords, particularly the light duty ones can create a whole new set of problems, not in any way related to the problems you already experienced. If I might make a suggestion, I would add a plastic bag down over the top of that block, leaving the bottom open for ventilation but preventing any blown in water.

 

As previously stated, there is nothing to apologize for. Our concerns are for your safety. Burned wires and the odor that you described mean heat in dangerous amounts in places that you do not want it. There are some very good theories being suggested here and there is nothing really wrong with any of them but it would take some time on site with a good meter to narrow it down. My recommendation is that you keep a close eye on the new load center and if you smell something, investigate immediately.

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Hi Lou-- thanks for the very clear and logical explanation. I went back to look at additional photos of the charred neutral buss (that I'd not posted to the blog) and found a close up where one buss screw clearly shows signs of corrosion, and there appears to be some faint corrosion on the buss bar itself too. So, even though I never found any of the charred neutral wires loose enough to pull out of the buss by hand, it seems highly likely that the top neutral buss wire's socket had corrosion, and this combined with the high draw of the space heater caused the wire (and eventually the whole neutral buss) to overheat and burn. By the way, this top wire was the one that was burned the furthest back.

 

close%20up%20neutral%20buss_zpsh9i9lbmy.

 

 

Following that logic, if I'm understanding this all correctly, that likely also explains the circuit breakers flipping at certain points of this extended fry-out (when the faulty connection was overheating enough to pull more current than the circuit was rated for), right?

 

Interesting hypothesis on the shore plug/surge socket too. The electrician suggested I start with the surge protector and work my way down the line to look for the problem. It was a TRC 30-amp full-EMS style protector (both high and low voltage protection), and was about 10 years old, so the pigtail ends had certainly been bended, pulled, and exposed to lots of weather over the years. I was able to pry open the box and examine the internal connections (all of which seemed tight and in working order), but the pigtail socket/plug ends were moulded and lacked any easy way to tear them apart to examine the plug connections, so I had just assumed the socket wiring was ok. Your explanation would now certainly make me second-guess that assumption! I threw the TRC out after dissecting it. I'll be buying a new Progressive Industries EMS going forward (probably the hardwired version to minimize these variables in the future).

 

Thanks again for everyone setting me straight on what likely caused this mess. Now even more a reason to spread the gospel to check those RV electrical connections regularly (for both tightness and corrosion).

 

Lynne

 

 



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Thanks Kirk. I took the panel off the new power center again today, and the new connections and new buss bars are still looking new and tightly connected. I've been running the ceramic heater a few hrs each evening for the past month, so the new components & wiring seems to be doing its job properly. I'll certainly recheck everything again the next time I move the RV.

Yes, I did indeed buy a heavy-duty outdoor extension cord for the hose and utility light setup. I would have preferred to have plugged those items directly into the pedestal, but the beige temperature-activated plug only was sold as a 2-outlet plug and would not fit there-- thus the need for the short extension cord. It might look rather hillbilly, but it's doing an awesome job at keeping my water line from freezing this winter!

 

Good suggestion to put a bag over the concrete block. We rarely get any precipitation here, and our packrats love any kind of enclosed space, so I refrained from doing that, but will throw a baggy over it when rain or snow are forecasted.

 

Lynne

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The faulty neutral connection was heating up the rest of the parts inside the panel, too. Circuit breakers are heat operated devices - when a bimetallic strip inside the breaker gets hot enough, it bends and trips the latch that opens the breaker contacts. So the added heat from the hot neutral buss bar probably made the breakers trip at a lower than normal current level.

 

On your newest picture, the top wire looks to be a larger gauge than the rest - if so, it's probably the one coming from the shore power cord. Being physically larger it would take longer to heat up than the smaller wires which is why it's insulation looks more intact but the damage spreads further back.

 

Starting at the source and working downstream is normal troubleshooting procedure. Downstream problems are easier to solve if you can first eliminate problems with the source feeding them. In this case the only mistake was not recognizing the hot neutral pin made the screw burn into the ground wire's insulation, instead thinking it happened the other way around.

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