MDShunk

The amount of "sag" in a conductor can be very easily measured with a stopwatch. This is a very simple procedure, still used today, that was developed way back in the days of the telegraph.

Manufacturers recommend a certain amount of sag in their conductors or cables, over a certain distance, at a certain temperature. First, you need to measure the temperature of the cable or conductor that you will be sagging. This can be done by cutting a short piece of conductor, pulling out a few of the inner strands, and inserting a thermometer. Alternately, there is a special thermometer, called a sagging thermometer, that is a piece of 1000MCM with a permanently mounted thermometer. Once the temperature of the conductor is determined, consult the manufacturer's recommendation for the amount of sag that conductor should have at that temp. Here's a picture of my sagging thermometer:




Once you know how much sag you want, in accordance with manufacturer's reccomendations, string up your cable or conductor with roughly that much sag (by eye). This is where you'lll measure the amount of actual sag. To do this, jerk the conductor or cable at one end with a rope, and lightly feel the rope to feel for each return "wave" of the conductor. Time the return of 10 waves, and look up that time you measured on a sagging chart. The amount of time you measured will exactly correspond with the actual amount of sag, in inches, from the sagging chart. The sagging procedure, by "The Return Wave Method", can be found in a quick 2 page read in USDA Bullttin 1726C-115 This bulleting also has the sagging charts, to look up the amount of time you measured in your "return waves" to see what the sag is.

There is a special stopwatch, called a "Sagwatch" that has the face recalibrated to measure the actual sag without a stopwatch. When you jerk the wire, measure 10 return waves, the stopwatch face will show the exact amount of sag in inches. Pretty neat. Saves looking up a regular stopwatch reading on a chart. Here's a picture of my sagwatch, from Sagline, Inc., in Millwood, NY.

Joe Momma

That is very amazing, I always thought they just pulled the wires up on the utility pole till they couldn't pull no more.
Never heard of a calibrated sag before.

Would like to know more about that thermometer, do you just leave it there next to the wire for a few hours? And why would temperature come into play with the sag? Temperature is always changing anyway, especially when you put current on it.

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Joe Momma was here

MDShunk

It's generally hung for about 20 minutes.

The sag changes with temperature. The manufacturers will have a chart for their cable that says what the sag should be at a certain temperature. For instance, if you did 12" of sag at 90*F, when it got cold, the conductor would tense up and snap. The sag that you set your conductor at has to be set with a certain temperature in mind, so that it's doesn't get too saggy when its' warm, or too tight when it gets cold.

Right!

Speedy Petey

Good information Marc.
Do you do a lot of pole and line work?

I do a small bit. I have a grip and block and tackle for hanging/fixing triplex. I also have a good lineman's belt and strap. That's about it as far as this type of equipment goes.
The belt is a great help on a tall ladder when making up taps.

Joe Momma

I have to say I like the looks of that thermometer, I'd like to have one around as a paper weight and to know the temperature on my desk as an added feature.

How much does a tool like that go for?

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Joe Momma was here

MDShunk

Mostly agricultural installations. I have a couple of customers who own a good bit of their own poles, and when they build new buildings, I need to add.

MDShunk

Right around 100 bucks for the conductor thermometer. The sagwatch is around 125, as memory serves.

Rhonda Wiley

How do I order the sagline stop watch?

MDShunk

Hi Rhonda

Here's the address and phone number on the box mine came in:

Sagline Incorporated
PO Box 351
Milwood, New York 10546
(914)248-8001

But this page has a different address and phone number:
http://www.ez-maintenance.com/resour...nce-II-31.html

In any event, HiLine supply has the sagwatch and the conductor thermometer in their catalog:
http://www.hilineco.com/pdf/148-160.pdf

scrooge

Good information. Thanks.bh.

Celtic

I'm constantly amazed.

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frenchelectrican

Marc.,, I dont know what to say but you really show us alot of very neat stuff even some item i don't even heard about it.

anyway with the sagmeter i heard about it but never see it in person at all.

but something new to learn along the way.

Merci, Marc

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Pas de problème,il marche n'est-ce pas?"(No problem, it works doesn't it?)

220/221

I think he makes this stuff up to see how gullible we are

bobelectric

We sag /tension lines to these little scales we hang on the tensioner,then start rachecting.

Ecopat

Brilliant, I always wondered how they compensated for temperature sag & now I know. Thankyou.

It never ceases to amaze me this industry.

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"Quid non Resolutio"

den

In the old days we did " corn field sagging " Then we went to using a level to check the actual sag in inch's and had to use the charts. We just hung a thermometer on the mirror and looked at it after dinner. The engineers started getting gouchey then and come up with all kinds of charts. Some of them were just plain wrong. I have seen a lot of 1/0-4/0 acsr that was so tight the line vibration would destroy the lead head and the insulater's fell off. The new plastic topped pins were a lot better.

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Old retired lineman turned electrician!

Peter D

I'm not. Marc is an alien, albeit a very strange one.