Electrical C Honnections

[rvhunter77@gmail.com]

Occasionally have difficulty plugging and unplugging 50amp male from various female adapters/sockets.  Most suggestions involve the application of brute strength, repeatedly plugging and unplugging the connection.  Recently discovered a supposedly dielectric dry lubricant called "Strike Hold"   http://strikehold.com/strike-hold-cdlp/

Does anyone have experience with this product  -- or -- any suggestions on how to overcome this problem?

 

[pethier]

subscribed

 

[Kirk W]

The 50a outlets & plugs are intended to fit very tightly because with the high currents that can be drawn through them a loose fit will introduce resistance and so generate heat. Enough heat and the plug and socket begin to degrade and in time fail. What I have long used on the blades of my RV power plugs is a silicone spray. That does make it less difficult to remove. 

[Ray,IN]

Dielectric means non-conductive, the use of dielectric grease is not universal, it has it's uses and not-good uses. In the instance of a 50A RV/marine plug where the female receptacle has good spring tension, dielectric grease is a proper application. There is a long discussion about the appropriate use of dielectric grease (participants are electricians and electrical engineers) here.  

[oldjohnt]

Good Neighbor Ray, GOOD READ on that prior technical discussion. My engineers take is there's a proper time and place for the use of THE CORRECT so called "Dielectric Grease"  Given the term dielectric is an insulator why would you want that (an insulator) between electrical connections is a valid question, but as the discussion goes to show IT GOES MUCH DEEPER THEN THAT and there is indeed a place for use of the "specific correct" product even if the name (dielectric grease) is less then perfect.

That being said, I keep my male plug pins bright n shiny and maybe use electrical contact cleaner now n then in the hidden female receptacles, but I DO NOT use any sort of oil or water based or other lubricants or greases or dielectric grease to reduce in and out friction for mating of plugs and receptacles.

Of course, if a certain specific product (whatever its called, dielectric or electrical contact lubricant or plug and receptacle protectant or lube or friction reducer etc.) is intended for and approved for that specific use, sure Id give it a try. I've just never come across a lube specifically labeled to reduce plug and receptacle friction but that sure don't mean it doesn't exist or that certain products even if not so exactly labeled wont still work just fine ????? Over many years I have seen folks spray the plugs and receptacles with the likes of WD 40, Silicone Spray, PB Blaster, Electronic Contact Cleaner, on and on and it didn't seem to "hurt" anything, I think I will stick with nothing for now unless I'm absolutely certain its designed specifically to make plugging and unplugging easier while NOT harming electrical conductivity caused by it being an insulator............

As always people are free to use what they please, this is just my way of doing things, no warranty its right or its wrong, I'm ONLY saying it works for and suits ME...........Do as yall please and whatever works for you.

 

John T

[Ray,IN]

John T, when I was working for ABB, the plant chemist came and asked what I would use on their distribution-line, blade disconnects. He said they were having arcing problems and  excessive resistance when the blade was closed when using dielectric grease. I asked if they had tried using water-proof, graphite grease?  The chemist shook his head and said "duh" graphite is a great electrical conductor. I've infrequently rubbed powdered graphite on my 50A plug prongs, couldn't decide if it helped unplugging or not, but it sure made my fingers black. Went back to nothing on the blades, just polish them with a "Scotch" kitchen pad now and then.

[oldjohnt]

 Ray, I'm sure most of us have used powdered graphite as a lubricant and graphite IE carbon can conduct electricity. It may NOT be a perfect conductor but I wouldn't classify it as a dielectric/insulator either. Like you I'm sticking with shiny blades and clean female receptacles not using any sort of "lubricants" at this time but NOT saying there aren't products out there that cant work just fine and are approved for plug and receptacle use ??????????? But I just don't know which products out there best serve the purpose of lubricating yet not hindering electrical conductivity in any way............. We may have to Google it lol

 

 John T

[Kirk W]

Whatever you use, it needs to be dry in order to avoid collecting dust, dirt, and grit of any kind. In 40+ years of electrical maintenance and repair profession, I have found that the spray silicone lubricants do not leave enough silicone to have much impact upon the resistance of the connections but will somewhat decrease the friction of insertion and removal. The problem with graphite or most dry power lubricants is that if used too liberally, they will migrate and cause shorting in bad places. I have also polished the pins of the plug which can help some, but a good, tight, fit is the most important part for long life.

[oldjohnt]

8 hours ago, Kirk Wood said:

but a good, tight, fit is the most important part for long life

AMEN Kirk,

John T

[Ray,IN]

15 hours ago, Kirk Wood said:

Whatever you use, it needs to be dry in order to avoid collecting dust, dirt, and grit of any kind. In 40+ years of electrical maintenance and repair profession, I have found that the spray silicone lubricants do not leave enough silicone to have much impact upon the resistance of the connections but will somewhat decrease the friction of insertion and removal. The problem with graphite or most dry power lubricants is that if used too liberally, they will migrate and cause shorting in bad places. I have also polished the pins of the plug which can help some, but a good, tight, fit is the most important part for long life.

You hit the nail on the head! The reason so many folks with 30A RV's have electrical issues is the over-used, maintenance-ignored, power pedestals in CG's.  I tell my friends to use  their own 50A to 30A reducer with their 30A RV when the 30A receptacle is loose.

[oldjohnt]

8 hours ago, Ray,IN said:

I tell my friends to use  their own 50A to 30A reducer with their 30A RV when the 30A receptacle is loose.

Good Neighbor Ray, more often than not the 50 amp receptacle is in better shape, newer, and likely served by adequate sized conductors with less voltage drop then an old 30 amp outlet, and sure that works fine. HOWEVER unless the adapter has the correct overcurrent protection included (it may well have, I'm NOT saying it does or doesn't) such improper overcurrent protection use would be in violation of the NEC (having to do with overcurrent protection and conductor ampacity) and poses some degree of a safety hazard but IM NOT intending to open that can of worms lol and anyone is free to use whatever they please is fine by me. But even if something works for 50 years and never causes a problem DOES NOT MEAN its safe or NEC approved........PS I carry a 50 to 30 amp adapter myself and may not "always" practice what I preach lol but just wanted to go on record as an old retired electrical engineer..........

  Hope to meet up again maybe when its cooler.........

 

 John T

 

[Yarome]

8 minutes ago, oldjohnt said:

....but IM NOT intending to open that can of worms lol...

LMFAO! And THERE it is...! I was just waitin to see if someone was going to crack "that" can. I'm not touchin it, myself... or when you throw an ATF and/or EMS into the mix.  A good morning chuckle though.. Thanks!

[ALLOY]

I like to use these

http://store.caig.com/s.nl/sc.2/category.293/.f

 

This is dielectric but I'll use it on the set screw threads in a plug or the studs on a terminal strip. Lasts for years

http://www.tefgel.com/

 

 

 

[Dutch_12078]

I wonder how plugging a 30 amp RV cord into a 50 amp outlet compares to plugging a 10 amp appliance cord into a 20 amp outlet...

[Kirk W]

1 hour ago, oldjohnt said:

I carry a 50 to 30 amp adapter myself and may not "always" practice what I preach lol but just wanted to go on record as an old retired electrical engineer..........

My 30a RV power cord has a 30a circuit breaker between the end of the power cord and the distribution box circuit breakers, meaning that the only thing which has changed when I connect it to a 50a outlet via the 50a/30a dog-bone is which end of the cord that breaker is on. Most, if not all modern RVs are built with a"main" circuit breaker that limits the supply at the RV end of the cord. 

1 hour ago, Yarome said:

or when you throw an ATF and/or EMS into the mix

I do use my 30a Surge Guard line monitor when using the 50/30 dog-bone as I do for all shore power sources or adapters. But I'm just a technician working in the practical world so I'll leave the theoretical arguments to you engineers. 

[Kirk W]

13 minutes ago, Dutch_12078 said:

I wonder how plugging a 30 amp RV cord into a 50 amp outlet compares to plugging a 10 amp appliance cord into a 20 amp outlet... 

 

I sent you a PM. 

[Dutch_12078]

3 minutes ago, Kirk Wood said:

I sent you a PM. 

Got it... Replied...

[oldjohnt]

Geeeeeeeeee the can got opened lol Yarome knew EXACTLY what I was talking about, he moves to the head of the class.

 

Like I said iffffffffffffff there's proper overcurrent protection a 50 to 30 amp dog bone adapter is safe,,,,,,overcurrent protection is satisfied,,,,,,,,,,,the NEC is complied with,,,,,,,,,,,and there's no potential safety hazard ALLS WELL fine no problem.

HOWEVER CONSIDER THIS, IF THERES NO OVERCURRENT PROTECTION BUILT INTO OR ADDED AT THE 50 30 ADAPTER ........  Maybe there is maybe there isn't,  IM NOTTTTTTTTTTTTTT SAYING YES OR NO if anyone knows please tell us

FYI Heres why it can (under certain conditions) be unsafe, a hazard, and NOT comply with the NEC

1) What's the overcurrent protection device in the 50 amp RV pedestal feeding the 50 amp receptacle

    ANSWER a 50 amp circuit breaker to protect feeders having 50 amps ampacity.  A 50 amp RV uses 50 amp rated wire

2) What's the ampacity of a 30 amp RV power cord (and guess what, there's a 30 NOT 50 amp breaker in the RV pedestal)

  ANSWER 30 amps

3) Hmmmmmmmmmmmmmm iffffffffff there's no 30 amp overcurrent protection device built into or added at the dogbone THEN THE HAZARD IS ITS POSSIBLE TO PASS UP TO 50 AMPS THROUGH WIRE (30 amp RV power cord)  RATED TO HANDLE ONLYYYYYYYYYYY 30 AMPS !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

4) With 30 amp rated wire (30 amp RV power cord) SAFETY AND THE NEC AND OVERHEATING DEMANDS A 30 AMP OVERCURRENT PROTECTION DEVICE NOTTTTTTTTTTTTTTTTTTTTTTTTTTT A 50 AMP which is what you have using a 50 30 dogbone that does NOT have built in or an added 30 amp breaker or fuse link to properly protect 30 amp rated wire  

 NOWWWWWWWWWWWWW here's something some may not, while some others understand and realize !!!!!!!!!

 A person may say BUT MY RV PANEL HAS A 30 AMP MAIN BREAKER and if there's more then 30 amps drawn the 30 amp breaker will trip PROBLEM SOLVED

WRONG WEEDHOOPER !!!!!!!!!!!!!!!!!!

The hazard and NEC violation and improper overcurrent protection remains in the 30 amp cord FROM the dogbone TO the RV main panel. Youre still using 30 amp wire protected with a 50 amp breaker (BETWEEN dogbone and RV 30 amp main breaker) THATS UNSAFE AND AN NEC VIOLATION. Remember, the RV 30 amp main breaker ONLY can protect loads after and downstream of the 30 amp main breaker NOTTTTTTTTTTTTTTTTTT frommmmmmmmmmm the dogbone tooooooooooooo the RV

NOTE the most hazardous and most risk is the unprotected 30 amp RV power cord laying there in the rain and mud where it can be ran over or stepped on or pinched. There's far less risk inside the much more protected RV interior wiring BUT THE 30 AMP BREAKER IN THE MAIN PANEL ONLYYYYYYYYYYYYY PROTECTS DOWNSTREAM LOADS AFTER IT, NOT IN THE OUTSIDE 30 AMP CORD     FROM     THE DOGBONE      TO     THE RV PANEL which is protected by a 50 amp pedestal breaker. A short in the RV power cord can draw up to 50 amps which can melt insulation and expose wires and deadly voltage and that WILL NOTTTTTTTTTTTTTT trip the RV panels main 30 amp breaker, its NOT seeing that 50 amps of current !!!!!!!!!! 

Its FROM the dogbone TO the RV where wire rated to handle ONLY 30 amps is protected by a 50 amp breaker IS THE HAZARD AND NEC AND OVERCURRENT PROTECTION VIOLATION

 NOW BEFORE ANYONE HAS A CALF Like Kirk was talking about, if there's 30 amp protection (to protect only 30 amp rated wire) then all is well and maybe the 50 30 dogbone has one or a guy can add one and if so the NEC is satisfied and theres no risk or hazard. I have one but never took it apart to see if it has some built in overcurrent protection ??? They make fusible wire links that look like regular wire so if it has 30 amp fusible links ALL IS WELL.

I'm ONLY saying if theres a 50 to 30 dogbone adapter used that does NOT have a fuse or fuse link, you have 30 amp wire NOTTTTTTTTT protected by a 30 amp device but a 50 amp BETWEEN dogbone and RV main 30 amp breaker. The RV panel breaker will trip if you draw more then 30 downstream and after it, but it will NOTTTTTTTTTTTTTTTT trip if theres a short or pinch or ran over etc BETWEEN DOGBONE AND RV. That's where the NEC requires 30 amp rated wire to be protected by a 30 NOTTTTTT a 50 amp breaker.........

Again use what you please I will not argue or try to stop you and if the dogbone has 30 amp fuse link or protection, then the 30 amp power cord is properly and NEC  approved and safe, but NOTTTTTTTTT if 30 amp wire is protected with a huge 50 amp breaker, BETWEEN DOGBONE AND RV 30 AMP MAIN where it lays in the open and gets ran over or pinched or a kid steps on it YIKES.

I hope this helps yall understand I'm here to HELP NOT ARGUE lol so do what you please I wont argue against it.  If you can show me an NEC exemption where its okay to protect 30 amp  RV power cord with a 50 amp breaker (remember BETWEEN dogbone and 30 amp main in RV)  IM ALL EARS LOL a person is never too old to learn so help me and all of us out here Id sure appreciate it.

 PS if anyone has info about 30 amp protection (fuse or wire link etc) built into those dogbone PLEASE LET US ALL KNOW. I'm ONLY talking about how and why its unsafe and violates the NEC if its NOT there.

 John T Long retired and rusty power distribution design engineer so no warranty at all but I still think you cant properly protect 30 amp rated wire with a 50 amp breaker  BUT IVE BEEN WRONG BEFORE AND WILL AGAIN SO PLEASE HELP EDUCATE ALL OF US     I still enjoy learning about electricity despite my advanced years lol   I'm tempted to go out and look at my 50 30 dogbone, hey I've used it so I'm NOT coming down on others mind you lol and no doubt people may have been using them 30 years and NEVER had a problem and most likely never will and that's fine...........................

 God Bless and best wishes to yall, keep safe out there now, hope to see you down the road.

 

[Dutch_12078]

John, I'm just trying to learn from an expert... What section of the NEC addresses over current protection when plugging in a portable device? Obviously, we routinely portable device plug cords into outlets with much higher current capacities than the cord in every day life, and that's essentially what an RV is, a portable device. I know the NEC addresses the interior dual voltage aspects of RV wiring, but I don't recall anywhere it specifies the breaker capacity of the outlet an RV is plugged into. You're saying that plugging a 30 amp RV into a 50 amp outlet without 30 amp protection at the outlet end is a violation, so I'm just curious what section it violates, since so many of are apparently doing so. Does the same section also consider plugging a 10 amp rated device cord into a 15 or 20 amp protected outlet a violation?

[Yarome]

11 hours ago, Dutch_12078 said:

...that's essentially what an RV is, a portable device.

Like I said... I'mma not gonna touch this one. "I" didn't open the can! 

[Dutch_12078]

Not really... Manufactured housing (mobile homes) are typically hardwired to the power panel and not easily relocated since the wheels are typically removed. Would you consider a stick built residence the same as an RV? They can be moved in most cases, albeit not easily. I have no idea what the total ampacity of the transformer on the pole at our cottage is rated for, but with three service drops connected to it, each drop is likely rated at quite a bit less. Many of the devices we plug in have multiple circuits within them, usually protected by multiple fuses, breakers, etc., but not many have over current protection at the plug for the often way under rated cord. I'm just curious where in the NEC the violation occurs. I'm not even claiming it's not a violation, just trying to factually document it. There must be some reference somewhere...

[Kirk W]

On 8/2/2017 at 2:09 PM, rvhunter77@gmail.com said:

Does anyone have experience with this product  -- or -- any suggestions on how to overcome this problem?

...........................     

[oldjohnt]

  Good afternoon Dutch,

 

  sorry my old NEC book is severely outdated and covered in dust lol I would have to take some time to read and re read then look back n forth at all the exceptions to copy all that's relevant and I'm sure there are exceptions for small appliance cords etc as you rightly mentioned.

 That being said in all my years of practicing power distribution when the NEC was my daily bible and attending numerous NEC updates the ONE thing I best recall is you first size the load,,,,,,,,,,,then size the conductors,,,,,,,,,then use the correct size of an overcurrent protection device TO PROTECT THE CONDUCTORS that's NOT citing any code section just basic NEC overcurrent protection theory which may be scattered all thru the code.

 I'm sure you understand how using a dog bone WITH NO 30 AMP FUSE LINK can allow up to 50 amps to flow thru only 30 amp rated wire and that a 30 amp main breaker in the RV panelboard DOES NOT SEE AND PROTECT THAT. I'm also sure there are small appliance exceptions but that's a bit different then a 25 ft piece of 30 amp rated rubber cord laying in the dirt or water with a 50 amp breaker.

 Anyway it was fun chatting with you and I apologize for not taking the time and effort to cite all the specific NEC sections to back up my thoughts, I'm too old for that lol AND AS ALWAYS FOLKS ARE FREE TO USE WHAT THEY FEEL SAFE WITH IM NOT HERE TO STOP OR ARGUE WITH THEM I only know what I learned in a 40 year career and what I feel is NEC safe and proper and that's the best I have to offer

NOTE if a person takes the time to look at and study Holts NEC forum I'm sure this question has been answered and if I ever get time I  may just do that  but I'm in the middle of home repairs as my farm may be sold and if so its even more RV travel time yayyyyyyy

Thanks again Dutch, best wishes n God Bless, sorry I dont have all the NEC sections to cite for you as you asked

John T   BSEE, JD  Retired Electrical Engineer and Attorney here in Indiana 

PS to cure this problem if the dogbone doesnt have it, simply add a 30 amp fuse or fuse link etc in a watertight handy box along with your dogbone adapter, that way 30 amp rated wire is protected at 30 NOT 50 amps yayyyyyy cheap n easy problem solved OR DO NOTHING IS FINE BY ME..............

  

[Dutch_12078]

Ok, John, just one last thought to keep you thinking... A standard 30 amp fuse/breaker nominally melts/trips with a 30 amp overload. At what amperage does the 30 amp rated 10 AWG wire typically used in 30 amp RV cords melt due to over current? The charts I've looked at commonly list 333 amps as the approx. fusing (melting) current of 10 AWG copper wire, and 247 amps for aluminum wire. Obviously that's substantially higher than it would take to trip a 50 amp breaker. That would seem to indicate that the cord could get warm if the overload ramped up slow enough to the trip point, but would trip almost instantly with a solid short. Think about it...

[oldjohnt]

Yo Dutch, while you and I are enjoying this, I fear we may be boring others to tears lol

Good points, here's my recollection. A conductors rated ampacity is NOT so much the current required for melting of the wire BUT CONCERNS DEGRADATION OF THE INSULATION to the point its no longer able to withstand the voltage potential and is no longer an effective insulator whereby wires could short out or worse could be exposed to a person or to a conductive material into which a person may come in contact or the RV's iron frame and skin YIKES..........That's why the ampacity can change due to the temp properties of the insulation IE theres THWN insulated wire and rubber covered wire plus the ampacity also changes due to the enclosure like in a conduit and with how many conductors or if in free air etc etc. A single conductor in free air has a higher ampacity then if 10 are enclosed in a conduit. When considering ampacity you have to consider the ability to extract heat and the surroundings and current generates heat and different classes of insulation can withstand more or less heat before they fail to be an insulator. 

ITS THE HEAT AND THE INSULATIONS ABILITY TO PASS X AMPS IN THE ENCLOSED WIRE BEFORE THE INSULATION DEGRADES MORE SO THEN THE AMPS BEFORE THE WIRE MELTS

Most circuit breakers are Thermal Magnetic whereby a sudden dead short high current draws trips the magnetic while a long slow high current near the rating trips the thermal.

Yes SUBJECT TO THE CLASS OF INSULATION and enclosure and other factors you can pass 50 amps thru 30 amp rated wire but eventually the insulation will degrade or loose insulation value and the hot wire may be exposed to a person or water where the power cord lays  etc etc.

I don't think one has to be an engineer or a technician to understand how allowing 50 amps to flow thru wire and insulation that's ONLY rated for 30 amps  can pose a hazard ESPECIALY in a wire that may be in water or get run over or cut or pinched between the main breaker and the huge 50 amp breaker in the pedestal. Theres a reason 50 amp RV' use 6 gauge wire and 30 amp RV's 30 amp wire and if the dogbonbe isn't equipped with a fuse link or fuse wire then that 30 amp rated cord can pass 50 amps if theres a short or pinch or a cut etc and 50 amps in 30 amp rated wire can degrade and ruin or even melt the insulation AND THAT JUST CANT BE A GOOD THING.

In like 40 years I don't recall situations (except for below)  or exceptions where you can use 30 amp wire with a 50 amp breaker and again its due to heat and what the insulation can withstand before failing not when the wire melts.

HOWEVER in motor branch circuits there are times (at least in days past maybe no longer) when you can use a breaker higher then  wire rating iffffffffffff the motor has overload protection and its allowed if the surge starting current trips a regular breaker.

Again I apologize for not taking the time to cite specific NEC sections but actually its more like the entire theory about overcurrent protection and many parts NOT one specific cite I might find.

The breaker is sized to match the ampacity of how many amps can flow before the insulation fails and while 40 in 30 amp wire is one thing, 50 in 30 amp wire is really pushing it and I can envision insulation failures and shorts or hot wires exposed to water or the ground or metal or the RF metal frame or you or your barefoot grandkids

Once more do as yall please I'm not perfect and have taken chances IM ONLY saying its my professional opinion its unsafe and an NEC violation to pass 50 amps thru 30 amp rated wire because the insulation may not withstand the heat generated

I WISH SOMEONE KNEW IF THE DOGBONE HAD A FUSE LINK OR FUSE WIRE ETC IT MAY I DONT KNOW BUT I DO KNOW ITS NOT SAFE TO (due to a short or cut or pinch or failure between dogbone and before 30 amp main breaker panel) TO PROTECT 30 AMP WIRE WITH A 50 AMP BREAKER. Even if the chances are slim and its worked for 50 years DONT MEAN ITS SAFE AND DONT MEAN ITS NOT AN NEC VIOLATION which I'm confident it is. If people dont mind  risk that's fine by me, heck its risky getting out of bed and driving an RV for sure  

I have used a dogbone and others have I'm ONLY describing how and why and what the NEC has to say about overcurrent protection and how the breaker is sized to the wires ampacity NOT NEARLY TWICE 50/30

Thanks again Dutch for the fun chat I really enjoyed it and maybe others learned from us, I know I sure have. After all this I have to add a short n sweet simple fuse box after my dogbone in order to practice what I preach lol

God bless and keep you all safe

 

John T