# Efficiency of braided vs solid wire

• posted on January 22, 2006, 6:16 pm
I have an outdoor receptacle (B)that is connected to a GFI outdoor receptacle (A) via a shielded extension cord-14?.B got wet, corrosion set in and I plan to replace it.I have been told that an outdoor solid wire from A to B would be better and that if I used a braided wire unless ALL the strands are securely attached it might conduct but not be able to handle a heavy load such as an 120 V electric water heater. True? Is there a way I can measure whether the braided wire is fully conductive
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Hank

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• posted on January 22, 2006, 6:59 pm
hankB wrote:

I don't know what a "a shielded extension cord-14" is and how it might be properly used in this situation.
All else being equal a stranded cable can carry more current than a single wire of the same gauge. The flow of electricity is primarily around the outside of a wire and in a stranded cable there is more of that outside area.
What are you hooking up here? It sounds like the whole plan is wrong from the start. I sure sounds like you are not following code from the start. What kind of water heater are you connecting to an extension cord? Is it a fixed appliance or portable.?
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Joseph Meehan

Dia duit
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• posted on January 22, 2006, 7:54 pm
The Litz effect, where more current flows on the perimeter of a wire than in its core, only really matters at high frequencies; at 60Hz it is virtually unmeasurable.
Just take care that all the strands are twisted together and under the retaining screw. You could solder the strands together to be sure or put them into a crimped terminal.
The capacity of 14G stranded and solid is identical. But check the load; if it is a hot water heater 14 might not be nearly big enough.
Joseph Meehan wrote:

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• posted on January 22, 2006, 8:01 pm
Most 120VAC electric water heaters have one 1500 watt element.

might
around
outside
wrong
cord?
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• posted on January 23, 2006, 12:27 am
Bennett Price wrote:

That's what happens when the college physics class was 40 years ago. :-)

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Joseph Meehan

Dia duit
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• posted on January 22, 2006, 8:55 pm
On Sun, 22 Jan 2006 18:59:08 GMT, "Joseph Meehan"

Maybe it's like what's used for cable TV lines along the street.

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Mark Lloyd
http://notstupid.laughingsquid.com
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• posted on January 22, 2006, 9:02 pm
Joseph Meehan wrote:

At 60 Hz? I doubt it.

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• posted on January 22, 2006, 7:36 pm

When working with stranded wire it is good to pay a little more and get better fixtures that use a screw tightened clamp to hold the wire, than trying to wrap the wire around a screw.
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• posted on January 22, 2006, 9:10 pm
John Hines wrote:

If you can't wrap the wire around a screw so that it is in full contact with all of the strands, then you should practice a little more or not do the work. A few stray strands separating at the cut end are not than uncommon and make no difference if the screw fully contacts the wire near the insulated end.
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• posted on January 23, 2006, 2:30 pm
hankB wrote:

There is no reason not to use solid wire. Stranded is more flexible and tends to be used for plugs for equipment rather than permanent installs.
The problem with stranded is the connection points. Also it tends to be bigger to carry the same load as solid core.
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Thank you,

CL Gilbert
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• posted on January 23, 2006, 4:24 pm

Generally speaking, solid wire is used for permanent wiring, and stranded for power/extension cords (in our code "portable cord"). The sheath is usually optimized for different conditions.
I can't make enough sense out of your description to know whether you're talking about the receptacle feed, replacing the extension cord, or what.
It sounds more like permanent wiring. Stranded wire is mostly irrelevant to house wiring (except inside some light fixtures/dimmers, and certain methods of using conduit and individual conductors, etc). For extension cords outdoors - especially long term use, it's almost always highly advisable to use pre-made extension cords with molded ends, which are both well connected in the plugs (often by welding) and vastly more water proof.
It's not a good idea to use solid wire in an "extension cord", because it'll fatigue/embrittle if exposed to any movement. In cold weather, most solid wire insulations will crack or shatter, and they won't stand up to sunlight exposure unless they're specifically rated for it.
It's virtually impossible to measure how well braided wire makes contact short of overcurrenting the connection (by several times the ampacity of the circuit) and seeing if it gets hot. Simply not practical.
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Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
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• posted on January 23, 2006, 5:57 pm
"heavy load" connected to outdoor GFI receptacle fed from another outdoor receptacle via zip-cord? Really? Why not put in some proper wiring, fastened with screw-terminals or anything better than what you get with a plug/outlet? Wiring suitable for environment.
Most aspects of electrical code have to do with fire prevention, and it sounds like you're heading the other way.
Are you devising this on your own? I'd suggest you consult a local electrician for tips.
J
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• posted on January 28, 2006, 6:39 pm
Hi Hank
The main reason one uses braided instead of solid wire is for flexibility. Solid wire fractures more easily than braided. A great example of this is CAT5e etc computer network wiring. (The blue stuff) In the wall they use single copper strands punched onto connectors. Once it goes from the wall to your computer they use braided wire...
When you terminate a braided wire in a screw connector you can actually get better contact than a solid wire as it distorts to fill the space better. A heavier turn on the scredriver would fix that for solid wire though.
Its the total metal cross sectional area (and type) that determines the amount of current that can be drawn. You will get a voltage drop in any wiring that can be defined as a loss of efficency. It does however go somewhere as radiated heat from the wire itself. Copper is about the best to use for money outlay. Aluminium and steel have more loss/distance.
A HWS I think is around 1500W. Thats about 13A at 110V or 7A phase to phase 220V. I'll admit I dont know US wire sizes too well but in Australia they had 7.5, 10 and 15A leads. 15A was suppose to have a special plug type. Given the low cost of the wire I'd suggest something that is rated at 25A min or so, just in case your HWS has dual 1500W elements.
You can measure the voltage drop over the wire when the known load is on. From that you can calculate resistance/conductivity and thus efficiency. Ohms law etc. Dont think I'd bother though...
Cheers Bob
hankB wrote:

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• posted on January 28, 2006, 11:19 pm
Bob Bob wrote:

A mild correction :
The correct terminology is solid, stranded, and braided. Each is different, and each has its application. Cat5e in the wall is generally solid. Drop cables are stranded (not braided). Braided is like what women do with hair.

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• posted on January 29, 2006, 1:01 am
CJT wrote:

Hi, In my book, braided means shild or ground. As a hot conductor there is stranded or solid or hollow(pipe) dealing with R.F. due to skin effect.
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• posted on January 29, 2006, 2:36 am

You do see braided conductors on lightning rods. Lightning can be thought ofd as a high frequency event and the shot flows on the skin of the wire Braided wire has more skin.
You can also spend a lot of money for "Monster" speaker cable but any frequency you can hear is wasted on that fancy braided wire.
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• posted on January 29, 2006, 2:31 am

You can measure the voltage drop between the wire a half inch from the receptacle, and the screw head that the wire is attached to. I've never done that but I would expect it to be minuscule, way less than a volt. Less than a tenth of a volt, I would think.
You don't have to have all the strands under the screw, but you should have almost all. Is that not possible? With the power off, twist the strands, and bend the twisted part into a clockwise hook. If a strand is in contact with the screw head or the part the screw screws into, or it's anywhere in the sandwich, that's as good as one can do.
In some cases you can solder ring or 2-prong pitchfork ends to the wire, and put that under the screw. Rings might not work because many times the screw won't come out all the way. Often home tools, mixmasterrs, etc. are done that way inside. But I don't think you need any end at all.
The most likely place, because of the acid in the battery and the reactions it causes, for a bad connection is between a car's battery post and the big lead connector on it. If it's *really bad* it will be hot to the touch.
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