Originally Posted By: mkober This post was automatically imported from our archived forum.
I’m a new member of NACHI and just starting a new home inspection business here in western Colorado. I’ve thoroughly enjoyed looking through the various message board topics, and would like to make a suggestion to all inspectors. When describing cracks in any concrete element, many people like to use the term “hairline crack.” This is a rather nebulous term, which doesn’t really say much in terms of quantitative information. You will come across with much more credibility if you can give a simple crack-width dimension, such as “in the range of 30 one-thousands of an inch” (written as 0.030"). Crack comparators (clear plastic cards with various-sized lines printed on them, all labeled) can be obtained at no cost from the Construction Technologies Laboratory, and easily fit into your shirt pocket. Just hold the card up to a representative crack (usually the widest area you can find), and slide the card to match a value with the actual crack beneath it, and take the reading. One person’s “hairline” may be actually closer to 1/16" or more–the human hair is only 0.003" in thickness versus 0.060" (1/16")–we’re talking a twenty-fold difference here. Envision seeing a human hair on a concrete surface more than an arm-length away–I know I can’t do it.
Originally Posted By: phinsperger This post was automatically imported from our archived forum.
mkober wrote:
Crack comparators (clear plastic cards with various-sized lines printed on them, all labeled) can be obtained at no cost from the Construction Technologies Laboratory,
Originally Posted By: mkober This post was automatically imported from our archived forum.
Yes, metal feeler gauges would work for determining crack sizes, but I strongly suspect using one would take considerably more time than a comparator. Sliding the comparator across the crack until the matching imprint-line “hits” is just quicker than retracting and poking various sizes of metal strips into the crack until the correct one is found. Over time, the accuracy of the feeler gauge would also be compromised by the recurring scraping of the tips against the crack edges. Hundreds of bridge inspectors working for highway departments across the country are using comparators, but I don’t know of any using feeler gauges–maybe for a reason?? I’m teaching several classes at a structural rehabilitation seminar next month where, in past years, comparators were handed out by the dozens by CTL personnel–I can try to get a healthy surplus of same and would be willing to send one to anyone in return for a stamped, self-addressed envelope.
Originally Posted By: phinsperger This post was automatically imported from our archived forum.
kmcmahon wrote:
Anyone know where you can get one of these cards for estimating electrical wire sizes?
I've also been looking for something to measure wire sizes. Not like these. I'm looking for a non-conductive scissors type caliper (like a long pair of needle nose) that would have a readout on the handle side indicating wire gauge with and without insulation. Something I can stick into a live panel  I can invision it but nothing like this seems to exist. Anyone interested in helping make a couple?
Originally Posted By: mkober This post was automatically imported from our archived forum.
Kevin,
At no time have I ever heard of CTL (formerly the Portland Cement Association) charging real money for their comparators. A stack of them as thick as a deck of playing cards was sent around the room at the last seminar I attended (2002), with instructions to participants to take as many as we wanted. I agree that 20 bucks is way too stiff for a comparator, unless they’re offering a new, super-duper digital, self-reading solar-powered electronic model that also does windows and dishes. I’ll repeat my earlier offer that I’ll send one to any NACHI member for the cost of a SASE; if I can’t get any freebies at my next rehab seminar in a few weeks, I have a few other sources to hit up (calling in favors, you know), along with checking my office’s nooks and crannies for any spares I can scare up. Maybe one of the upper management group at NACHI could be convinced to put the squeeze on the CTL for a few thousand of the things–either that, or all of us may be inclined to start recommending treated timber foundations be mandated to replace all cracked concrete ones! Lacking a comparator, the options are automotive feeler gauges (not recommended), or reverting to calling every crack you see as “hairline.”
Originally Posted By: kmcmahon This post was automatically imported from our archived forum.
mkober wrote:
Kevin,
At no time have I ever heard of CTL (formerly the Portland Cement Association) charging real money for their comparators. A stack of them as thick as a deck of playing cards was sent around the room at the last seminar I attended (2002), with instructions to participants to take as many as we wanted. I agree that 20 bucks is way too stiff for a comparator, unless they're offering a new, super-duper digital, self-reading solar-powered electronic model that also does windows and dishes. I'll repeat my earlier offer that I'll send one to any NACHI member for the cost of a SASE; if I can't get any freebies at my next rehab seminar in a few weeks, I have a few other sources to hit up (calling in favors, you know), along with checking my office's nooks and crannies for any spares I can scare up. Maybe one of the upper management group at NACHI could be convinced to put the squeeze on the CTL for a few thousand of the things--either that, or all of us may be inclined to start recommending treated timber foundations be mandated to replace all cracked concrete ones! Lacking a comparator, the options are automotive feeler gauges (not recommended), or reverting to calling every crack you see as "hairline."
Michael J. Kober, P.E.
Mike,
My post was in reference to the electrical wire guage that Paul H. (post above mine) linked to. 
Originally Posted By: mkober This post was automatically imported from our archived forum.
Astute Inspectors:
I guess 1/16-inch qualifies as “hairline,” as long as we’re all in agreement that it’s a bull African elephant hair, fortified by heavy doses of Rogain.
Originally Posted By: tallen This post was automatically imported from our archived forum.
The best way I know of; to get the different wire gauges, is to>> go to an electrical supply house>> ask them for 6" of every gauge and every different insulation type they have. I would guess most would just give the samples to you. Whatever, Get them, anyway remember there are lots of different types of insulation ie: Remember TW 14awg. is just as thick as 10awg thhn/thwn. Or you get to a point were you can tell by looking at it.
This is really beyond a HI's scope. Just learn what 14 thru 8 looks like.
I had a 1 awg alu. the other day and I could not for the life of me remember what it was rated at!!! I had to go back and look it up 
Anyone own a tape measure. The small lines are 1/16th’s LOL