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davidshultz2007 03-15-2013 06:10 AM

R there any bad effects for over sizing wires?
Im getting a small wind turbine setup installed. If all goes well I might add a larger second one, just testing the waters first. My concern is not on the distance and voltage drop over the long distance. My concern is once the power arrives at my shed, where the controller and the battery system is going to be located at. If I oversize the wires from my disconnect, through my fuse, through my charge controller, and to my batteries, what are the consequences. I mean I have 2 fuses in place already for protection. Are their truly any negative side effects (besides cost) involved for oversizing a wire. I live on the coast, and wind gets really high at Im thinking to prepare for the gushes of wind that regularly occur. Can anyone clear up this debate that's offered me contrary answers whenever I ask it from other windturbine owners who arent as experienced as they try to sound when it comes to electrical issues Thanks in advance

COLDIRON 03-15-2013 06:30 AM

I am not an Electrician but I will start it off, I am sure you'll get plenty of answers from qualified people.
The larger wires should not cause any problems as long as. The proper size fuses are used and the connection lugs are sized to accept the larger wires.

darren 03-15-2013 07:38 AM

You can always go bigger, the only issue may be fitting the larger wires under the lugs of your equipment. The lugs usually take a variety of wire sizes but is possible to have wire to big for your lugs.

davidshultz2007 03-15-2013 08:02 AM

so all this nonsense Ive heard from people about too big wire size can be just as dangerous as too small is crap? Logic says it kinda would be, because I can see an undersized wire building up heat and eventually melting the insulation, but I cant see any harm if the wire is too big. Heat wouldnt buildup as quick (reach amp limits) with a thicker wire. So, is it safe to really say, bigger IS in fact better - if you can afford it? P.S. one of these online turbine salespersons started this concern for me as he raised the issue that thicker wire can be just as dangerous as too thin. That sparked all the confusion as I could tell my neighbors unsure gave their opinions not electrical facts

gregzoll 03-15-2013 08:09 AM

For our building at work, instead of running one large set of wires for the 3 phase drop, they ran two runs of smaller to equal the larger, then just lugged to the underground run to our building, due to it is 400 amp service inside.

Go with the largest that you can expect that depends on which turbine you may be using, but not so large, that as others have stated, it will not fit into the lugs, or work for the connections to the junction point at the mast.

jbfan 03-15-2013 08:14 AM

Make sure that what ever size you use, the lugs are rated for that size.

COLDIRON 03-15-2013 08:17 AM


Originally Posted by jbfan (Post 1137670)
Make sure that what ever size you use, the lugs are rated for that size.

"Already stated many times"

jbfan 03-15-2013 08:28 AM


Originally Posted by COLDIRON (Post 1137672)
"Already stated many times"

Can't be stated enough.

AllanJ 03-15-2013 08:52 AM

Oversized wires will not degrade the current flow compared with "the correct size."

Unlike water and plumbing, a fatter wire over part of the run is an improvement (less voltage drop) compared with the thinner wire over the entire run. (However no part of the run should have wiring thin enough that overheating is a problem, such as 14 gauge wire in a circuit allowing more than 15 amps.)

davidshultz2007 03-15-2013 09:31 AM

Appreciate it guys. Everyone seems to be in consensus and it follows what sounds electrically logical to me. If anyone has anything to add to the contrary please do

How anyone anyone can run a business misinforming their customers is beyond me, but I WILL NOT be doing business with the guy who I found out works out of his garage and was simply clever enough to create a nifty website that appears professional. Not off to a good start.

So thanks for all the responses. Feel free to add any considerations to this -- Im all ears

gregzoll 03-15-2013 09:47 AM

There is not anything wrong with people working out of their garages and having a business. It comes down to if they know their stuff.

One of the girls my wife works with, her mom runs a plumbing supply business out of her home, with majority of the sales being special order.

ddawg16 03-15-2013 09:53 AM

How about some info on the wind gen? How high is it going to be? What size wire are you talking about? Are you going to be doing DC or AC? Is your converter going to be at the fan or the POU?

As noted above, larger wire is not an issue. If you never add to the system, the only real loss is the extra expense.

Don't expect big current surges from wind gusts....the mass of the fan will dampen those and the fan should have a speed limiter as well as a regulator for the output.

Glennsparky 03-15-2013 12:01 PM

It's good practice to label an oversize wire at the breaker. State max breaker size and reason. Typical would be "max breaker 15A, derating". Yours might be "max xxA, load nameplate".

There are legal workarounds for wires too big for lugs. The workarounds would retain the benefits of the larger wire. Just tell us the wire size and type, and the specs off the lug's label; range of wire sizes, AL/Cu, and temperature rating.

Aluminum wire especially can get big, fast. AL is tricky becouse you have to torque the lugs. But it's cheap and the modern stuff is good.

davidshultz2007 03-15-2013 12:17 PM

Thanks guys - but my only concern was 'if larger conductor size would harm my setup in anyway'

According to this one guy, who took a photo of a building and put it on his website as if to make others believe that was his warehouse but is actually working out
of his garage, according to him, he made it seem like going bigger would cause harm to my entire setup.

It all didnt make sense, and many here have reinforced what I thought to be true -- bigger wont hurt.
I dont mind spending a few extra bucks for a thicker wire...but only so long as it wont create potential hazards to the system or my property

Dorado 03-15-2013 12:30 PM


Originally Posted by davidshultz2007 (Post 1137660)
so all this nonsense Ive heard from people about too big wire size can be just as dangerous as too small is crap? Logic says it kinda would be...

Your comment about logic is the only thing I disagree with. I keep reading that bigger is fine but even if there's no lug problem I bet there's either a specialty wire so thick that's being used somewhere what would cause a problem, or else there's a theoretical wire so thick that it would cause a problem. If you dig a long ditch, about 5' x 5' wide, and fill it with molten wire grade copper and wait for it to harden and try powering household stuff with it, don't you figure there would be a problem?

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