Monday, July 15, 2013

High tensile questions

 
 
I can never tell what people will be interested in when I write what I do.  You, dear reader, have been more interested in fencing than any recent post I've done.  I've gotten questions via email and postings, and I'll do my best to answer them here. 
 
Q:  Why 8 strand fence?  People use less strands of fencing elsewhere.
 
Each species of animal has a different type of fencing that works best; different height, different spacing of wires. 
 
With pigs a standard 34" hog panel works most of the time; pigs never jump; they work more like bulldozers, pushing right through with four wheel drive and massive power.    They are most deterred by fencing that is at their nose height, and with different size pigs there are a number of heights.  So a close spaced set of wires at the bottom works best.  The bottom wire is 4" off the ground, and they're spaced at 5 inches apart for the next few wires.  That's the pig portion of the fence. 
 
With sheep, you don't need a heavy duty fence, but they can jump.  A standard 34" hog panel does not contain a sheep, but a 60" cattle panel does.  So you need higher wires, but they can be farther apart, too.  So the top wires on this fence are 9" or more apart, and the total height of the fence is about 60". 
 
The cows I have are a large-framed breed; I have some Holsteins, and one of my cows stands about 6' tall at the shoulder; she is a very big girl.  About 1400lbs.  A Holstein that size considers a 48" fence to be a roadbump.  She'll walk up to it and keep paddling until she gets a leg over, and then continue walking over it.  Field fences don't work with Holsteins, in my experience.  Another reason for a 60" fence. 
 
Outside the fence are a lot of coyotes.  I know that they'll get through the fence - they will probably dig under it eventually -- but in doing so they'll tell me where they're entering and leaving, and I can easily control them.  I'd rather not kill the coyotes, although I've shot my share of them.  It's not because I'm a softie about coyotes; I've just found it better and easier if I can do what I can to give the coyotes a non-lethal lesson and avoid livestock-coyote conflicts where I can. 
 
the other thing that exists around here in quantity are both deer and elk.  Both travel up and down the valley and a single deer can wipe out your garden or landscaping.  This fence won't stop a determined deer or elk  -- they can jump over it -- but it's less work for them to walk around, and there's corridors on both sides of my property so they can easily move up and down the valley as they choose.  Again, choosing to avoid conflicts with wildlife. 
 
Plus the additional strands aren't that much more money.  

 Q:  How do you stop the electric fence from contacting wood and shorting out? 
For the electric lines as they cross a post there are plastic tubes that cost about a dime that you slip over the wire and tack down.  The picture above shows three of them. 
 
At the posts at the end of a run there are longer plastic tubs that slip over the wire and around the post and insulate it from contact there.  Pictures of those tubes below. 

This is the simple end of the fence; the spring/pulleys are at the other end. 

 Q:  What are your costs, installed? 
The longer the run, the less cost per foot.  What costs money are the braces on either end and the hardware to tension the wires, and the labor to put it all together. 

Below you'll see a picture of the springs and ratchets at one of the braces.  Here's the cost-per-strand for the hardware: 

Tension spring:  $8
Tension ratchet: $4.50
Wire:  $129 for 4,000', or $0.032 (three point two cents) per foot.   You need about 40' of wire to connect it all together and allow for wastage, so about $1.20 in wire. 

So the total per strand is $13.70

the braces I'm using are 5 ground contact 6x6 posts, 8' lengths, at $32.00 each. 
Nails and bracing wire add another $8.  I use 12.5 gauge barbless barbed wire for the diagonal bracing.   

Total cost per brace (two per span) $168.00, or $336.00.  Add $27 if you cement posts in. 

It takes about 6 hours of labor to dig the holes and construct the braces
It takes about 5 hours of labor to assemble the spring-and-pulley system. 
It takes about 2 hours to actually run the wires and stretch them.

Call it 12 hours labor for each span.   At WA state minimum wage that'd add $108 or so per span. 

The brace and tensioning are fixed costs.

So for a four-strand 300' long fence it would be: 
4 x $13.70 (pulleys, springs) $54.8
2 x $168  (double h braces) $336
300 x $0.032 x 4 (fence  wire) $38.4, plus wastage, call it $45

$435.8,or $1.45/foot materials cost. 

for an 8 strand 300' long fence it would increase the cost by $126.00, to $561, or $1.87/foot materials cost.

 For a 500 foot span of 8 wires you'd be looking at  $573.6 or $1.14 a foot, materials cost.  the longer the span you can run between braces, the cheaper per foot.  the wire is not the expensive part of the fence. 

I've left out one element. You'll probably want a couple of field posts along the span to support the wire and keep the spacing correct.  They don't have to be very big or sturdy; I'll probably use 4" treated round poles, but for my fence it looks like I can put them in at 100' intervals and get the results I need.  Some folks like them closer, up to you.   Figure $7 per  post or so. 

It takes a while to tie up all of the pulleys and springs. 















4 comments:

George said...

I hope you slid a few extra of those plastic insulators over the HT wire before stapling and tensioning it all up :)

I usually put an extra one on each strand every couple posts along the fence in case something breaks one, etc etc.

Dave Perozzi said...

Bruce,
Nice fencing. Here's a suggestion that might save a little work. Unless you specifically need the spacing between the spring and the tensioner, you can connect them together without the short length of wire. Just pull one of the U-shaped clips out of the center of the spring, pass it through the hole in the tensioner, then squeeze the ends of the clip and reinsert it into the spring.
I've been using that on all my newer fences. I don't have a picture of mine handy, but I found one online:
http://extension.missouri.edu/explore/images/eq0379art03b.jpg
Dave

Bruce King said...

George; we've been putting 5 extras in each span as I'm not sure how many line posts I'll need, and having a few extra is cheap, I agree.

Dave: thanks for that suggestion. You saved me a bunch of time this morning on the next span. It went from having to tie 4 knots to 2, and that's a good hour or more per span. Thanks!

off grid mama said...

I have to disagree about pigs not jumping... while their tendency is to go under they can jump if so inclined. I had a boar decide he wasn't going to stay where we put him. First, he bulldozed into another pen and then jumped a 3.5 ft fence in the next. My favorite (heavy sarcasm) is when they crawl up the cattle panel so you're looking at them face to face. My high tensile fences aren't quite so elaborate ...