At the risk of showing my intelligence I have to ask a question ’cause I don’t want to wreck my tools.
Running a mitersaw, a sidewinder, a little table saw. Always working solo so only one tool running at a time. No major cutting. Short spurts. Maybe rip short lengths of 1x pine and crosscut 2x8s. Cut some osb.
New issue of DeckBuilder came and I’m reading Hot Tips about ‘Eliminate ‘Voltage Drop’ Problems. Says don’t plug a 12gauge into a 10gauge extension cord but doesn’t explain why.
I’m working a ways out back and haven’t run a line out there yet. So little cutting to do so I run some extension cords out there from the house.
From the 100amp panel there is 35ft to the receptacle outlet. From there I run a 10gauge 600 V extension cord 100ft and from there a 75ft 12gauge and a 50 ft 12gauge to the saws. No noticeable loss of power or slow starting.
I’ve been leaving the cords outside so I placed a type of yellow firebrick underneath the plug ends where the two 12 gauge join and leaned a short 2×8 cutoff on top of it to keep the moisture off.
I moved the plug ends and saw that there is a 1/2 inch hole about an inch dia like an inverted cone now drilled in the brick right underneath where the plugins were lying. Like it brazed a hole in the brick.
Now I’m sweatin’ bullets fearing I’ve been abusing my tools even tho everything seems to be running up to snuff.
Is that too long a string of cords for a short light cutting time?
sobriety is the root cause of dementia
Replies
No problem for the tools unless the plugs are really loose, which you would probably notice.
What caused the hole in the firebrick is another question. FB under welding arcs on it all day long won't put a 1" hole in it, so it isn't something like a connector arcing, although the voltage drop on a loose plug/receptacle combo could be greater than the whole wire string. (about an 8 V wire drop over your 200 ft string)
Anything moving or vibration, or do you see some wear on the plug? as FB is pretty soft and it could be just the cord getting pulled back and forth.
I often use a spool of 12-2 romex for a 250 ft extention cord laying on the ground for currents up to 50A for a welder (so, BFD that it aint per code, its in the open air on the ground, not in an insulated wall) at 20% duty cycle, no problems with the wire or the welder, but I would not try running a sidewinder at full load at the same time.
No movement at the plugs. They're thick jacketed black neoprene rubber. Maybe I'll post a pic tomorrow of the brick. I never saw such a thing.sobriety is the root cause of dementia
Well, my tools have been nice enough to let me know when they are having trouble with low voltage - they slow down, cut more slowly, and start to get warm, then hot. Usually I'm smart enough to notice the slowdown and ease up on the feed rate to let the tool work easier and thus not overheat. (A tool with a built-in fan runs faster with the correct voltage and thus blows more air for cooling.)
About the cords and voltage drop: You can figure the voltage drop for each cord from the current you're drawing and the cord resistance. The tool's nameplate current is a good starting value - push harder and it draws more; lighten up and it draws less.
Figure each cord resistance like this:
(a 100 ft cord has 200 ft of current carrying wire)
#14 wire - 0.5 ohms per 100 ft.
#12 wire - 0.3 ohms per 100 ft.
#10 wire - 0.2 ohms per 100 ft.
(It's pretty hard to measure the cord resistance with a small meter - the meter leads themselves may have as much resistance as your cord and will give you an incorrect reading.)
Soooo - your 100 ft #10 cord has 0.2 ohms.
The 75 + 50 ft #12 cords have 0.375 ohms.
(0.3 ohms/100 ft, or 1.25 x 0.3 = 0.375 ohms.)
The total resistance is 0.575 - call it 0.6 ohms. With a 10 amp draw, you'll lose 10 x 0.6 = 6 volts (120 v. -> 114 v.). 4 amps loses 2.4 volts (120 v. -> 117.6 v.). 20 amps as you saw through a knot loses 12 volts (120 v. -> 108 v.), etc.
(There is still a bit of loss between the outlet and the panel, between the panel and the power pole, between the power pole and the generator, etc. Those losses are beyond your control.)
I can't see any problem with connecting cords with different wire sizes (as long as you're still on a 15 or 20 amp circuit).
Now, the gotchas: sometimes the plugs and sockets will become worn and will lose extra voltage at the connection. The clue is that they get hot or sometimes HOT or sometimes arc and spark and sputter and get REALLY HOT! It might be cheaper to replace the cord rather than buying and installing the proper heavy-duty replacement plugs.
I'm not sure about the hole in the firebrick - maybe from overheating? (Overheating firebrick??? :o)
Another possibility is, if you leave the cords outside, and they are plugged in (hot), and they get wet, you might have been doing some electrochemical experiments with the damp cord and brick and electrical leakage.
So, it is doubtful that you are damaging your tools - especially if you listen to them when they "tell" you they're in trouble!
There's another nay. Thanks, I feel better already.sobriety is the root cause of dementia
There's absolutely nothing wrong with plugging a 10 ga extension into a 12 ga or vice-versa. On long runs you should use the largest (lowest gauge number) extensions you have.
As someone said, often the worst problem is the connections. After using an extension under load for a few minutes it's good to check the connections and see if any are warm.
I like the heavy-duty cord ends that have clamps for the screw terminals so that the wire is clamped vs just sort of captured under a screw. A lot easier to wire, too, and less likely to come loose inside.
PS: I'll bet the hole in the firebrick was there already, or resulted from a defect in the brick that became apparent when it was thermally stressed.
Hi Rez.
Have you had an electrical storm somewhere within 12 miles or so of your place? Sounds like there was some weak leakage to ground at the plug and an electrical surge caused by powerline or lightning entering the power line found a good path to ground at your point of discovery.
Heavy humidity and cool air at night can condense under the plank. Do you have a ground fault circuit breaker protecting the extension cord? If so has it been tripping?
If you don't have a ground fault protection please get on now. The next time that same surge could do you in.
Regards,
Virginbuild
I bet it was those dam* carpenter bees!
Several folks have correctly pointed out that extension cord ends can be worn and generate a lot more heat and voltage drop as a result.
How to prevent that from happening: Never plug or unplug a cord under load. Turn off the motor and then unplug the cord.
This happens the most often (and worst) with air compressors. It has drained overnight, someone plugs it in and, with 12 amps on the nameplate, it will pull 50-60 amps of starting amps through the line.
As the plug ends are getting close (1/100"), the current jumps the gap. A 50 amp current, even for a fraction of a second, erodes and oxidizes a lot of metal. The burnt looking blades (and the receptacle you can't see inside of) have a lot more resistence and therefore get hot and even more oxdized over time.
Twist locks....
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming.... WOW!!! What a Ride!
Anyone know why they are saying not to put the 100ft 12g into the 100ft 10g?
This was in the latest 'DeckBuilder' mag.sobriety is the root cause of dementia
I think they are recommending against 200' of extension cord, not plugging the 12 into the 10.
Jon Blakemore
I considered that but then got to wondering why they would specify a 12g into a 10g as an example.sobriety is the root cause of dementia
Because most people with two cords will plug the larger one in first, and the smaller one into that.
I think they were assuming that anyone with two 100 footers would have bought a 12 first, then a 10 when they realized the power drop. This is quite common. How many here had a 12 and a 10 for years ? You can't quite bring yourself to buy another 10, or to get rid of that 12...
I do think they they were just trying to say don't use 200 feet. Get ####generator...
I also think the hole was already in the brick, and you just didn't notice it.
Also, I have seen FB get holes drilled in it just by water dropping on it. And I don't mean over a long time, either.
"Criticism without instruction is little more than abuse." D.Sweet
I wonder how many here use 10 ga. cords? I have a 50'.
Anybody with 8ga. or better?
Jon Blakemore
I've considered making a 100ft 8ga but barring wiring into a breakerbox, what would you use for plug ends?
sobriety is the root cause of dementia
That would be a problem. I would think a 4way box on the out end would work well, but plugging in might pose some difficulty. Maybe splitting the line into to 12ga. ends and using two plugs?
Of course I did start thinking about this with regard to mounting a generator permanently on a trailer. And if I did have to plug an 8ga. cord in to the house's system, I would want to be as close to the panel as possible.
Maybe a 220 plug with only one hot leg attached?
Jon Blakemore
Hubble makes just what you need.. Teist lock the ends and feed a spider box with it...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming.... WOW!!! What a Ride!
There's no need to use heavier plug ends on a long 8ga cord vs a short 12ga. The reason for using heavier wire is not to carry more current but to reduce voltage drop at a given current. The voltage drop of a plug and socket connection is essentially fixed for a given current, regardless of the gauge of wire connected to it.
The only problem with the heavier gauge wire (from a plug standpoint) is finding a plug that will physically accept the larger wire, and if that's a bottleneck you can splice a short length of thinner wire onto the ends.
Well this thing puzzles me so I took a pic of the brick with the hole in it alongside the cord plugin which sat over that hole. That board was placed atop the plugin for moisture protection.
I always unplugged the cord at the house recp. when not in use. And I'm sure I would have noticed that hole in the brick when I first used it.sobriety is the root cause of dementia
"Geodesics have an infinite proliferation of possible branches, at the whim of subatomic indeterminism.",Jack Williamson, The Legion of Time
Electricity is pretty spooky stuff, much more mysterious than, say, trigonometry, IMO. But I would be deeply, deeply surprised if electricity did that to your brick without leaving any marks on the connectors.
Edited 7/11/2004 2:53 am ET by Uncle Dunc
There are no flash marks on either the brick or t6he connectors.
There is another, smaller pockmark on the upper left of the brick. Almost covered by the cord.
Even when you are paying attention, sometimes something even as obvious as this gets missed.
"Criticism without instruction is little more than abuse." D.Sweet
If the connection got hot enough to damage the brick, it would have gotten hot enough to scorch the board and scorch/melt the plastic connectors.
Some fire brick can be easily damaged by moisture. If the connector caused moisture to stand underneath it while the rest of the brick dried out and maybe got a little warm in the sun, that could have caused spalling. (But there would have been loose brick chips there in that case.)
If there's no brick chips/dust and no scorching of the plastic or wood then the brick must have already had that divot in it.
Well bust my barnacles and bowl over my butt ya friggin' bunch a pirates are accusing me a not seeing outta my one good eye. ;o)
I'll accept the heat and moisture theory as a possible but to say a compulsive type like myself could place the plugends directly on top of a divot like that and not notice it is a stretch.
In fact that would have made honorable mention in my memory recall as I plan on using those brick in a future fireplace I am mulling around on.
As long as Im not inadvertently damaging my tools I'm at piece with it.
I just like to know the howcum of things like this.
Cheers.I just looked at that pic again and that divot is fresh from comparing the color of the face!
"sobriety is the root cause of dementia.", rez,2004
"Geodesics have an infinite proliferation of possible branches, at the whim of subatomic indeterminism.",Jack Williamson, The Legion of Time
Edited 7/11/2004 10:21 am ET by rez
There is another possibility -- electrolysis. In the rain there would have been a non-trivial current flowing between the plugs and the surface of the brick. Probably not enough to cause any heating, but enough maybe to chemically alter the brick. This could have caused the surface to disintegrate.
yeah, an remove all the unwanted,unsightly brick hair.
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
Sphere, you're a consistently funny guy, and every time I read one of these witticisms I wish I had been quicker and as sharp as you. Like Wyatt Earp said, "He makes me laugh."
"beware the man who maketh you laugh , he's probably doin yer wife"
me.
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
I have #6, 8, 10 and 12 for lenghts...
A bunch of 14's in short lenghts.
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming.... WOW!!! What a Ride!
How long is your 6ga. run? Is it easy to manage?
Jon Blakemore
400' 6/3-WG/SJWO 600V... Twistlocked for a 240/110v/50A distribution turtle....
And no it is not easy to manage... One heavy mother
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming.... WOW!!! What a Ride!
Where did you find Deck Builder Magazine? I'm interested in a subscription.
Someone on here I believe posted a link once.
Website is... http://www.DeckMagazine.com
sobriety is the root cause of dementia
They're telling you to not go over 100'
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming.... WOW!!! What a Ride!
Ah, I see that.
Kinda funny way of conveying the thought.
sobriety is the root cause of dementia
Edited 7/10/2004 1:06 am ET by rez