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Thread: what is the best frequency to Locate gas and phone with?

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    Member Danger's Avatar
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    Cool what is the best frequency to Locate gas and phone with?

    OK, I was trained to start low, and work my way up. Recently, there was a 600 pr damaged on one of my long projects. I had it marked and had the documentation done. However, the contractor spotted a irrigation line and failed to spot the 600 pr. the damage happened and I was within tolerance ( the bore crew pusher decided to shoot about a foot off my marks.) The thing that is troubling me is now my group manager thinks I need to spend more time with my supervisor because he thinks I am " in love with 8 mhz." so basically I'm looking for some opinions... my manager thinks I should use 33mhz for everything.... I generally start with 512 and work my way up...

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    Senior Member Enjoythefall's Avatar
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    Default Re: what is the best frequency to Locate gas and phone with?

    I've always had luck with 8.19 khz. That or 512mhz. I don't know why they would say that... there really isn't a problem using the lower frequencies as long as you are getting a clean signal. I actually hate jumping up above 8.19khz because anywhere above that and I have major bleedover problems.

    Honestly, 8 is good for phone... But for your job's sake, If you have to start using 33 and you want to make sure you're not bleeding over onto cable or power, Unbond at the house and the ped. Another way to tell is the size of the peak you're getting. Phone tends to be a small peak, but with a fairly linear rise and fall. Cable is usually around the same size rise and fall, but the peak is smaller compared to the rise and fall... and electric is usually broader than either.


    The only time I need to go above 8.19 is when I'm tracing an unlit streetlight. Usually if I hook up to the nearest transformer (Or even a service) and shoot a high frequency at it, I can trace the line alright.

    As far as the bleedover there goes, I just check the line I'm tracing with radio and Power modes. Once you've done it, you can really tell the difference between phone, cable, and power lines. They sound different. I wouldn't mark exclusively with passive, but it's always good as a trouble-shooter when it comes to telling what you're actually tracing.

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    Default Re: what is the best frequency to Locate gas and phone with?

    Isn't that ass backwards at what they preach. they always stress low frequency. Now the bore crew failed to spot the 600 pr and bored only a foot off your marks which is inside the 18" mark. So your manager wants you to use 33KHZ which has a much better chance of bleeding off. I would request it in an email from your manager. GEt it is writing his requesting you to locate in 33KHZ

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    Senior Member headcipher's Avatar
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    Default Re: what is the best frequency to Locate gas and phone with?

    I would agree with the start low on any cable/telco/power, but not on gas. I would start at at least 33kz if not 65kz. I personally use an 810 (83kz), mostly for gas, which happens to be in my opinion the best machine for finding gas. Especially since Gas is the one utility that is installed in a way to never be commonly grounded, and because of that have the smallest chance of bleed-over.

    Of course, there are always exceptions.

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    Default Re: what is the best frequency to Locate gas and phone with?

    I had a sheath damage using 32. Everything unbonded and it still picked up the drop that was running semi-above it. From that moment on I only ran copper with 8.19..
    Unless im on a long country road ill use 512 and run it forever..

    As mentioned above your supervisor is wrong. The lower the frequency the tighter the signal; 32 however is a good all around frequency but when it comes to copper id say always the lower the better.

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    Default Re: what is the best frequency to Locate gas and phone with?

    well the equipment I use is a vivax, and I actually love that I have more frequencies to work with. I was using an RD 4000 (that was what was used to locate the 600 pr that got hit). I found the T3 transmitter limiting because I only had 8, 33 and 65 to work with. Not to mention the receiver was out of calibration by more than a foot.
    I guess the reason for this tread is to express my frustration. The training is umm, pretty good.... but you get out in the field and find that in some areas it is lacking. Then you have people contradicting training... and that coupled with my analytical nature you evaluate it and realize that about 50% of locating underground utilities is luck.... unless you dig down on every mark you put on the ground there is no way for sure to know what you are locating... especially in this area where that 600 pr was hit, because the installation of the utilities defies what we were trained to believe. ( you have phone at 6 and 7' deep in some places, other places its only 2'... you have secondaries run at 3', and gas ran at 3' in some places and 9' in others... then there seems to be no rhyme or reason to the way they ran it... you have phone lines crisscrossing each other, phone criss crossing gas lines and power.) Training says you can't count on the depth readings, and I have personally found this to be correct. Then again I was trained to use those depths and amperage readings to verify that I am on the right utility... You unbond and direct connect to a phone line and you pick up signals on power, phone, and another utilities fiber... and that was using 8 mhz.... so which one do you mark? if you mark it wrong, you get dinged, if you mark it right... and the contractor hits it anyway... you get dinged... if you mark everything you get a signal on... then you loose respect of other locators and piss off the contractors. just seems like everything is against the locator... no one seems to really like or respect us.... including the companies we work for.... these are questions I really should be posing to my supervisor, or mentor, but they are over loaded and don't have time... but since I got dinged for that contractor hitting a 600 pr that was marked.... by them taking 2 of my projects away from me... I guess I'll have more time to think about it....

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    Senior Member RD_Wrangler's Avatar
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    Default Re: what is the best frequency to Locate gas and phone with?

    33KHz has it's place...locating copper phone isn't it. Particularly if it's a congested easement.

    Your supervisor is a twit if he tells you otherwise.

    Isolate, use a Hz frequency (512, 640, etc.), and verify by mA readings. Read everything you can find online about Antenna Theory, Electro-magnetic theory, Ohms Law, etc. Luck has LITTLE to do with it. Training will only take you so far, and if you want to be GOOD in this industry, the rest is up to you. Read, learn, and learn to apply what you learn. When in doubt post here. There are MANY successful (and knowledgeable) technicians that will be happy to help.

    Also learn to ignore twits like your boss telling you to use heavy resonance frequencies in a congested area to locate phone...
    Last edited by RD_Wrangler; May 12th, 2011 at 12:58 AM.
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    Default Re: what is the best frequency to Locate gas and phone with?

    Quote Originally Posted by RD_Wrangler View Post
    33KHz has it's place...locating copper phone isn't it. Particularly if it's a congested easement.

    Your supervisor is a twit if he tells you otherwise.

    Isolate, use a Hz frequency (512, 640, etc.), and verify by mA readings. Read everything you can find online about Antenna Theory, Electro-magnetic theory, Ohms Law, etc. Luck has LITTLE to do with it. Training will only take you so far, and if you want to be GOOD in this industry, the rest is up to you. Read, learn, and learn to apply what you learn. When in doubt post here. There are MANY successful (and knowledgeable) technicians that will be happy to help.

    Also learn to ignore twits like your boss telling you to use heavy resonance frequencies in a congested area to locate phone...

    Good post!

    As you get more experience you'll see that those who continue to believe that locating is at least 50% luck will be lucky enough to get damages in lucky numbers like 3 or so at a time.

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    Senior Member daman1's Avatar
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    Default Re: what is the best frequency to Locate gas and phone with?

    Quote Originally Posted by Danger View Post
    well the equipment I use is a vivax, and I actually love that I have more frequencies to work with. I was using an RD 4000 (that was what was used to locate the 600 pr that got hit). I found the T3 transmitter limiting because I only had 8, 33 and 65 to work with. Not to mention the receiver was out of calibration by more than a foot.
    I guess the reason for this tread is to express my frustration. The training is umm, pretty good.... but you get out in the field and find that in some areas it is lacking. Then you have people contradicting training... and that coupled with my analytical nature you evaluate it and realize that about 50% of locating underground utilities is luck.... unless you dig down on every mark you put on the ground there is no way for sure to know what you are locating... especially in this area where that 600 pr was hit, because the installation of the utilities defies what we were trained to believe. ( you have phone at 6 and 7' deep in some places, other places its only 2'... you have secondaries run at 3', and gas ran at 3' in some places and 9' in others... then there seems to be no rhyme or reason to the way they ran it... you have phone lines crisscrossing each other, phone criss crossing gas lines and power.) Training says you can't count on the depth readings, and I have personally found this to be correct. Then again I was trained to use those depths and amperage readings to verify that I am on the right utility... You unbond and direct connect to a phone line and you pick up signals on power, phone, and another utilities fiber... and that was using 8 mhz.... so which one do you mark? if you mark it wrong, you get dinged, if you mark it right... and the contractor hits it anyway... you get dinged... if you mark everything you get a signal on... then you loose respect of other locators and piss off the contractors. just seems like everything is against the locator... no one seems to really like or respect us.... including the companies we work for.... these are questions I really should be posing to my supervisor, or mentor, but they are over loaded and don't have time... but since I got dinged for that contractor hitting a 600 pr that was marked.... by them taking 2 of my projects away from me... I guess I'll have more time to think about it....
    It's not really luck as much as it is just getting the feel for it. There's no way to teach that. If you care about what you're doing and don't give up when it gets hard, you'll eventually be able to tell when something is bleeding off and you'll learn what works best on the problem jobs. The ungodly maze of wires and pipes down there are never gonna make sense. Don't apply too much logic in figuring out why, you'll go nuts.
    Personally, I will run in 33 for gas and 8 for copper. If there's conjestion, go lower. Make sure EVERTHING IS COMPLETELY UNBONDED! I've found it's better to mark something out if it tones up that's not there than to NOT mark something that is. Let the contractor know. They'll usually try to avoid your uncertain areas IF THEY CARE. As for loosing respect, we never had any to begin with. A low damage ratio is the best you can do to earn that. Just do the what works best and don't worry about who likes it.

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    Member Danger's Avatar
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    Default Re: what is the best frequency to Locate gas and phone with?

    ahhhhhhhhh I learned my lesson about telling contractors anything. The contractor that hit the 600 pr tried to tell our investigator that I told him the signal I marked up on the hill was the 600 pr... when I had told him I got a signal up the hill so I marked it.... from here on out.. if I tell the contractor anything. It will just be what is in the ground, and not where... it's their job to pot hole and identify...
    and here is an update. The very next day I get a call from the contractor saying they got into something... so I go down to check it out.... they are shooting a bore right beside the 60 strand fiber that they hit last week, under a splice pit.... over the top of an unlocateable 4" MP gas line... right under a phone ped, a cable dog house, and right under a duct run which has the redundant loop for the 60 strand that they hit last week in it...( this fiber supplies the network for Kaiser). So needless to say when I got down there I was a bit tense.... I had it marked, photographed and documented.... but I called my supervisor anyway.... they uncovered their head... and got lucky... they were 4" below my duct run... and hit an un marked 3 phase power that dipped just below the duct run.... needless to say they haven't made another shot since....

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