Not really 250ft. in a roll of romex?

[mivey]

According to the Southwire rep I talked to, their lengths are -0%, +5%. This does not mean that the measurement is off, only that they may stop the run at a length up to 5% longer than you ordered and you could pay for the extra 5%. That's the official story from Southwire. Well almost, the industrial rep was not in, so they transferred me to the next most official person.

Another manufacturer's rep said they were set up to err on the + side (that's what the plant tells them). Building wire in standard lengths would be paid by the standard length so you would get the extra for "free". For custom-ordered wire, you would pay for the extra that came out of the run. I know some guys at one of their plants and I can get the official scoop from the ones who actually have their hands on the process. I'll ask the next time I'm there, if I don't forget.

Finally remembered to ask. According to an actual hands-on person at one of the plants:

Most wire is measured to 0.1" during the manufacturing process. They maintain an average of +/- 1 % when spooling the wire (can actually get to +/- 1/2%). The biggest error is due to human intervention. People stand in a different spot when they cut the wire, spool up the machines differently, re-set the counters differently, are knuckle-heads, just plain out make mistakes, etc.

His advice: If you want X number of ft, you better add the tolerance the supplier gives you or you may be short.

He did not think that a 250 ft roll of cable at a supply house will always be 250 ft, but that a truckload of rolls should average pretty close to that. He said he would expect it to average on the minus side, but within published limits.

 

[tom baker]

I have always been told by wire manufacturers that they had a plus or minus ten percent tolerance

Yes I had a manager of a wholesale tell me they supplied 1000 ft wire spools for a job, a 1000 ft pull and they were short.

 

[kid_stevens]

I just got 800 feet of 8/3 Simpull Romex and it was 5 feet over on a custom cut. The roll was just reeled back up 10 minutes ago. This thread made me look at the new roll.

 

[denny3992]

How about using an ohmmeter?

How about using an ohmmeter?

measure resistance , then compare to what it should be? alot simpler than rolling out 250' of RX

 

[Speedskater]

measure resistance , then compare to what it should be? alot simpler than rolling out 250' of RX

I think that the machine that makes the wire pulls the copper through a "die" to make it the proper gauge. As the die wears the diameter will change. It won't take much wear to change the cross-section area by 1 % and that's equal to 2 and 1/2 feet.

 

[iwire]

You can bet they keep the die pretty darn accurate as running a larger diameter then needed would mess up conduit fill and cost the factory extra copper.

You can measure wire length with resistance but not with a run of the mill multimeter.

 

[realolman]

You can bet they keep the die pretty darn accurate as running a larger diameter then needed would mess up conduit fill and cost the factory extra copper.....

.

Not that they'd care whether or not it would fit in the conduit, since they don't even care that they give you 10% less than you ordered.:wink:

'course that would fit in the conduit. It just wouldn't stick out the ends:smile:

Now, costing the factory extra copper... now that they'd care about!

 

[Speedskater]

Let's see, 250 feet of 14 gauge is about 0.63 Ohms. I have a 4 terminal Ohm-meter with 100 micro Ohm resolution, but I don't have a 250 foot roll of cable.

 

[sitsom]

15 pages of dicussing the length of romex!? I just read the first few post but what's the whole 15 pages about or did it just get off topic? I mean WAAAAAAY off topic.

 

[DonP520]

Weigh 10ft = ? X 25 will give you 250'ft

 

[quogueelectric]

We just unloaded 60,000 feet of #10 stranded on 500' reels I will see if I can pull some true tape in with some of the runs if I end up pulling this wire in.

 

[wptski]

Not about to read this whole thread to see if its been mentioned! Although I've had mixed results using a TDR on Romex, some users here say theirs are accurate. How about using one to check a few spools?

 

[kid_stevens]

measure resistance , then compare to what it should be? alot simpler than rolling out 250' of RX

We rolled it out to cut it into the different lengths for the 4 different apartment types and then staged it with the new panels and breakers. 48 unit apartment complex with ITE panels all set with 100 amp disconnects and every single panel has burned up buss bars and or missing breaker tabs (burned off).

 

[kid_stevens]

Not about to read this whole thread to see if its been mentioned! Although I've had mixed results using a TDR on Romex, some users here say theirs are accurate. How about using one to check a few spools?

You could not use a TDR on a rolled up spool. They will return false results. I used a TDR at least once a week for 11 years in the Navy and boy do they freak out on rolls of cable.

 

[wptski]

You could not use a TDR on a rolled up spool. They will return false results. I used a TDR at least once a week for 11 years in the Navy and boy do they freak out on rolls of cable.

Yeah, that's right, you reminded me!

 

[bradleyelectric]

15 pages of dicussing the length of romex!? I just read the first few post but what's the whole 15 pages about or did it just get off topic? I mean WAAAAAAY off topic.

Nope, this 1 stayed pretty close to topic. You really didn't miss anything.

 

[dtstellwagen]

Have experienc with mc cable

Have experienc with mc cable

I don't know about nm, but I can tell you about mc cable. I was doing prefab for a midrise, hundreds of 20 foot lengths of mc, buying on 955 foot rolls, sold as 1000 foot rolls. Told by parts house it was sold +/-5%. The manufacturers certainly have equipment to verify that their equipment isn't mistakenly giving out too much wire, and they can use the same equipment to cut 4 1/2% short. (Don't even consider the idea that mc stretches, the jacket has some give and take, but the copper inside doesn't, and I was cutting the copper within 1 inch at 240 inch lengths, .4%!). On the other hand, the "Southwire" Romex I most recently bought has the length stamped right on the cable, I didn't bother to look at both ends, but I cant imagine that they would stamp the length each foot at 11 inches, so the length would be easy to check.