POWER CORD - Page 2 - Montana Owners Club

Dave e Victoria · 12-04-2005, 09:54 AM

Seems like this is easy to solve. Just coil in a figure 8 and then pickup the two coils together in a single pile. No more induction. Ain't physics wonderful?

Any way, this is another one of those urban myths you can put right next to never store a lead acid battery on concrete. There is no way an air inductor made of a cord wrapped like the fifty amp cord in a laundry basket is going to cause a problem. The heat in a coiled extension comes from good old resistance. The coiled cord warms up because you have a whole bunch of heat in a small area. If you are pulling a bunch of current through an extension cord and its all pushed together in a pile youare going to have a heat problem no matter how it is rolled up. The longer the cord the more problem. The smaller the cord(diameter not length) the more problem. So, in the summer, It will always be better to use a 25 foot of 50 amp cord rolled up in a basket than a 25 feet of 30 amp cord.

Now that we are past any real world situation, It is true, you could make up a transformer from your coiled cord by including a second coiled cord in the pile where the second cord is plugged into itself. The second cord looks like a shorted turn. Even then, I doubt that the coupled energy at 60 hertz would be sufficient to trigger a response unless the coil was really wrapped tight. Might be a fun experiment.
Dave

richfaa · 12-04-2005, 10:00 AM

The figure eight is good..Physics never fails...

Parrothead · 12-04-2005, 11:15 AM

Thanks Dave for clarifying. Our previous 5ers had the power cord coiled inside the unit so if there was a fire hazard, I'm sure they would not have done that. Plus the basket has holes so air gets to the cord to help keep it cool.
Happy trails.................

richfaa · 12-04-2005, 11:19 AM

Quote:

quote:Originally posted by richfaa

It is doubtful that such a thing will happen in a Rv ...but a picture is worth a thousand words...

Dave e Victoria · 12-04-2005, 01:17 PM

Resistance got you. Use a shorter cord or a heavier one next time. That looks like 14 gauge with a big load on the end. If it had been a result of an induction the whole winding would have smoked not just a local area.

richfaa · 12-04-2005, 02:44 PM

After 35 1/2 years in electronics I learned that there are times when theory and logic take a hike and stuff happens....

Dave e Victoria · 12-04-2005, 04:23 PM

Got yah by a couple of years. I graduated in 63 froM GMI with a BEE. Retired in 63(sort of). Whole career was in electronics-most in aviation stuff. I agree, stuff happens. But there are no mysteries. Everything has a reason and as my favorite physics professor used to say, "It all starts with f=ma." I was never good enough to go that far but, I did find a little dimensional analysis had a way of revealing the "secrets."

Anyway, enough of this. Have a happy Holiday, keep your nose up in the turns, and don't wrap your cords too tight. (opps, that should be tightly)
Dave

dsprik · 12-04-2005, 04:34 PM

Quote:

quote:Originally posted by Dave e Victoria

There is no way an air inductor made of a cord wrapped like the fifty amp cord in a laundry basket is going to cause a problem.

I did an experiment when I was in the 7th grade, after doing science experiment at school... electromagnet w/ copper wire, nail, paperclips... we've all done this. But I immediately rushed home after school - my parents weren't home... who needs their unnecessary, silly safety precautions...

and I proceeded to take an old lamp cord, found a 2" dia 24" long aluminum pole (didn't know iron was better - unnecessary research, I figured

) and proceded to wind the cord tightly around the pole. I looked around... couldn't find a car battery... I know! An outlet in the house! This is going to be great!

I split the end of one end of the cord, stripped two inches bare on both wires, and proceded to demonstrate my science wizardry. We had the old glass fuses back in those days... made a mess of them, not to mention the scorched wallpaper 3/4 of the way up the wall when the flames shot out of the outlet (never seen that much fire EVER come out a house outlet since

). I did not get electrocuted somehow, but I did hit the back wall of the room trying to escape. My parents were amazed when they got home. I couldn't even start to cover up that disaster

. After my punishment

, Mom and Dad proceeded to hide all the household chemicals from me... go figure... back to the drawing board.

Quote:

quote:The smaller the cord(diameter not length) the more problem. So, in the summer, It will always be better to use a 25 foot of 50 amp cord rolled up in a basket than a 25 feet of 30 amp cord.

You can get the same effect by using an under rated ext cord to power a large amp power tool. It will get very hot, where as a properly rated, larger amp cord will not generate anywhere near that amount of heat.

Quote:

quote:Now that we are past any real world situation, It is true, you could make up a transformer from your coiled cord by including a second coiled cord in the pile where the second cord is plugged into itself. The second cord looks like a shorted turn. Even then, I doubt that the coupled energy at 60 hertz would be sufficient to trigger a response unless the coil was really wrapped tight. Might be a fun experiment.
Dave

I'll watch from a distance, Dave... my hair is already falling out...

I wonder, though, if you took a large metal pole and rapped about 25 ft of 30 amp cord around it (the more windings, the better), turned on the A/C and microwave... and see how much metal you could pick up... Oh, wait... I forgot... my hair. Nevermind...

Dave e Victoria · 12-04-2005, 05:00 PM

Dave,
The devilis in the details. A few feet of lamp cord plugged into a lamp socket could have burned the house down all due to resistance heating. True, in the process you had a hell of a magnet although rather imperfect using the aluminum pole. It probably got warm too. This sort of reminds me of when my brother let the gun go off in the house. Couldn't hide that either. Glad it made an impression on you. May have saved your life in later years if you knw what I mean.
Dave

ols1932 · 12-04-2005, 05:07 PM

With all the physics and electromagnetic theory going around and all the different situations, my advice is still: DON'T DO IT! Why open yourself up to a possible problem? This is from an "old-time" electonics/electrical/technician.

dsprik · 12-04-2005, 06:05 PM

Dave, it really did make an impression on me. Unfortunately, the scope of my learning on that incident seemed very narrow, as I have managed to do SEVERAL other stupid things in my life... ever throw a pound of pure sodium metal in a small pond? BAD, BAD, BAD... But then again, we were only college students at Mich Tech at the time. And NO, I was NOT the one who stole it out of the chemistry lab (we had to take the whole jar as sodium has to be stored in mineral oil because it reacts violently with the humidity in the air)... I was able to talk my roommate into that...

The resulting explosion and fireball would have elevated our National Alert level in today's environment.

dsprik · 12-04-2005, 06:07 PM

I think everyone's alert level has been raised on this. Thanks, Orv, Dave and Rich!

richfaa · 12-05-2005, 02:16 AM

Quote:

quote:Originally posted by richfaa

It is not an entirely good thing to leave that long 50amp cord coiled up and hot.A electro magnetic field can build up inducing heat and thereby fire...in can happen...

This post certainly generated a lot of interesting information.I always keep my friend Murphy in mind,,if it can happen..it will.

I noted a thread on another RV forum. It was titled what do we/did we do for a living.It was like over 70 pages long and I spent a couple hours reading it.It was absolutely fascinating as to the diversity and knowledge that exist among Rv'ers.I think it would be a good topic for this forum..what think you moderators???

jpkelpe · 12-05-2005, 11:09 AM

My husband, the science retired teacher says that K works about the same way--I wonder how he knows.

dsprik · 12-05-2005, 11:36 AM

Yes it does, Jan... ever heard of gunpowder, or fertilizer? K is main ingredient. K = Potassium, BTW for the non-science teachers. They in the same Family (column) in the Periodic Table, right next to each other (means they have similar properties). OK that's more than most of you wanted to ever know...

BTW, I believe all farmers/orchard growers know the the Federal Govt now has to have Co-Ops document EVERY pound of fertizer sold, or unaccounted for, on a regular basis Large volumes must be tracked by the Feds. OKC bombing changed things for farmers.

mobilrvn · 12-09-2005, 02:13 PM

Electricity has always been "FM" to me--the M stands for magic and you can figure out what the F stands for

. We had a problem with the 50 amp plug coming apart and the kindy tech fixed by trading it off for a "better" quality one they had laying around their shop. The old one was stiff enough, but this one takes two fat men and a boy to sort of coil it into the basket. My question to you EE types out there is why does the 50 amp cord have to be so heavy? Seems to me that a power line coming into a stick house isn't as bulky. Are the more flexible/lighter materials which can be used?

dsprik · 12-09-2005, 03:35 PM

Good question, Bill! I'd to see the answer to this also. I have one permanently bad shoulder and one recovering from surgery. If there is any material that would work that is easier to manipulate, I'd love to see it.

Parrothead · 12-09-2005, 04:00 PM

Maybe they all really well insulated so they won't start a fire!

Happy trails.....................

dsprik · 12-09-2005, 04:18 PM

Sue, I love your "Fired up" Smilie! Where did you find that one. I was looking for something like that when I was posting about my home science experiment.

Wrenchtraveller · 12-10-2005, 02:33 AM

I just got my little adapter pigtail from CW . I got it so when I run my generator I won't have to use the " BIG 50 AMP CORD" Yikes 50 amp stuff is expensive. 69.00 dollars for that little thing is a lot of money but I phoned all over and Marine supply places wanted even more for them.

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