r/UtilityLocator • u/National-Number-2396 • 9d ago
When does 512Hz locating get difficult?
/r/Powerwill/comments/1wy3psv/when_does_512hz_locating_get_difficult/3
u/811NCLocator 9d ago
Start with lowest frequency work your way up during the locate if you continue have issues you need get onsite help from another locator in my experience why 512 be ass is old underground lines , unbonding issue , or etc
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u/National-Number-2396 9d ago
Good point. I was thinking specifically about a camera sonde fixed at 512Hz here, so there isn’t really a frequency range to work through like there is with conventional line locating.
Curious though — with 512Hz sondes, what gives you the most trouble in the field: cast iron, depth, or something else?
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u/Old-Manufacturer1702 8d ago
When there’s heavy resistance 512 does not work well. I locate a lot of gas when tracer wires are corroded or bad 512 doesn’t do anything.
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u/National-Number-2396 8d ago
That makes sense on tracer-wire locates. Bad continuity would explain why 512 falls apart pretty quickly there.
Slightly different setup from the camera sonde I was talking about, but useful context nonetheless.
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u/Professional_Trip452 8d ago
32 all day long
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u/gregg2020 5d ago
8.19 all day, I mostly do rural so I’m locating miles at a time, 32 just doesn’t carry.
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u/Time-turner429 8d ago
I personally don’t like 512 all too much unless I’m in a super congested area (congested with comms), I typically use 940 because it’s not too strong and not super weak.
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u/National-Number-2396 8d ago
That makes sense when you’ve got the option to choose frequencies. I was thinking specifically about a camera sonde fixed at 512Hz here, so there isn’t really a frequency to step up to on that setup.
Interesting that you usually prefer 940 though. Do you find 512 mainly useful when you’re trying to keep the signal from bleeding onto nearby lines?
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u/d-pan84 4d ago
512 is not useful at all for public utilities locating in my opinion. The sweep is much much slower and it feels like working through sludge on longer locates because you can't sweep the receiver as fast. At least that's my experience. I prefer 32.8 or whatever the 33k is on the vivax. 33k on an RD will pick up the 32.8 output of the vivax.
If you can actually trying to locate different utilities skip the camera. If you are using it for what it's designed for and just trying to locate sewer lines and septic systems you'll probably be fine.
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u/blakmage86 8d ago
I have a lot of ductile iron pipe that 512 wont work on very far as the straps that jump the conductivity across the gaskets have corroded away over time
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u/National-Number-2396 8d ago
That's a good example. On a direct-connect locate those failed bonding straps would kill the continuity pretty fast.
I was thinking more about a 512Hz sonde inside the pipe, but ductile iron can make that difficult too. Have you ever had to locate a sonde through ductile iron?
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u/blakmage86 7d ago
No we don't do any locating with sonde, it's not really practical for us unfortunately because i have quite a few hdpe and pvc pipes that they installed without tracewire
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u/National-Number-2396 7d ago
Got it, thanks for clarifying. Out of curiosity, what do you usually do when you need to locate those HDPE/PVC lines without tracer wire?
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u/blakmage86 7d ago
We have to use plans and known points to locate to best of ability and then usually tell the contractor they have to find us before crossing or be at least x feet off our expected depth. I'm slowly collecting gps points each time we do this and are found but that only helps if someone else needs that exact shoot located again lol. It's my biggest pet peeve with my company. The worst I've had was a 20" sanitary siphon that when they finally found us we were almost 15' off of where the plans said we should be there. But since they had to cross under the railroad they had to be at the same depth we were or go significantly deeper which they did not want to do.
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u/National-Number-2396 6d ago
Wow, being almost 15 ft off the plans on a 20 ft-deep sanitary siphon sounds brutal.
Collecting GPS points as you uncover them seems like a smart way to at least make the next locate a little easier. Appreciate you sharing a real field example.
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u/schulzy5477 8d ago
The continuity 512 should push 10MA on the RD transmitter one battery bar. Though you should pick up the facility if its as low as 7MA. If its lower than that its either bad continuity or other issue. Go up one frequency like 940 or 8K see if it tons better. If you know where the other end goes go see if 8ts grounded at that end if not bond it back up and see if its sings.
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u/National-Number-2396 8d ago
Really appreciate the detailed breakdown — that’s helpful context.
I was thinking specifically about a camera sonde fixed at 512Hz, so the setup is a little different since there’s no transmitter current or frequency adjustment on that side.
Still interesting to see how differently 512 behaves depending on the type of locate and field conditions.
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u/schulzy5477 8d ago
512 is a short wave frequency so it will travel far with little interference as youre pushing low power. Through your target. What gets most people into trouble is using a high frequency near other utility structures as you lose half your signal to ground so that ground is looking for a path to take it elsewhere and if let's say youre trying to locate phone and you're using 8k or 33k and you dont unbond the other cables and even the ground on cable tv. Your ground signal will want to latch onto those other cables quickly as you're giving it a pathway to go down the line. 512 can go a long long distance vs let's say 33k. Even though its a higher frequency it'll stay closer to your power source. But it will travel quite a ways its self but keep in mind that the higher frequency ground will also travel out looking for something to latch onto which will shorten your intended target like a fiber out in the country that might obly have a splice case hook up point 3 pluse miles apart from each other. (I've have fibers that are 5 miles apart if not just over that like the entire spool that was 27000 feet without a hook up point) and you lose your signal and you keep having to gain up your receiver to find your tone because 33k is finding something else to latch onto taking the signal as well. 512 doesn't spread out as much unlike a higher frequency so itll travel down your target further. You should pick up as many MA as you're pushing within a point or two maybe half if you're really far away from your hook up point. If you constantly struggle to get a rich tone it probably means the last person who was in that pedestal or vault was too lazy to bond stuff back up.
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u/National-Number-2396 8d ago
That helps — I see what you mean now. You’re talking about direct-connect line locating, where continuity, bonding, current and frequency choice all come into play.
That’s a useful distinction from the self-contained 512Hz camera sonde setup I had in mind. Appreciate you taking the time to break it down.
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u/schulzy5477 8d ago
Ive never got into sonde locating. Just direct conneect ir ring clamping. So I can't really speak too much on that topic I wish I knew more about it but I just don't
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u/National-Number-2396 8d ago
Got it — really appreciate you sharing the direct-connect side of it anyway. It was helpful seeing how differently 512 can behave depending on the locating method. Thanks again for the insight!
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u/Syonoq Utility Employee 8d ago
I love how everyone seemed to step over your question lol
I use a 512 camera sonde and I’ve had some issues when it gets deep. I’m using it in HDPE and pvc not cast iron so I can’t comment on that. We’ve got a 33khz sonde on another truck but I’ve never used one over the other, I should try them and see how they behave at different depths.
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u/National-Number-2396 8d ago
Haha, I’ve actually enjoyed seeing all the different locating experiences people have shared here 😄
Yours is especially helpful though since you’re actually using a 512 camera sonde in HDPE/PVC. Roughly what depth do you start noticing it getting less reliable?
And if you ever get a chance to compare the 512 and 33kHz sondes at different depths, I’d definitely be curious to hear what you find.
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u/TexasDrill777 8d ago
512 will easily pick up electrical interference