EM Line Locating · Direct connection · clamp
Active Line Locating by EM.
Apply a known frequency to a target line and trace only that line — the precise, unambiguous core of electromagnetic locating. Direct connection or signal clamp puts a traceable signal on a specific conductive utility so it stands out from everything else in the ground.
Free phone consult · No pressure · Mon–Sat 8am–6pm PT
Best suited for
Why it's used
- Highest-confidence trace — the signal is on YOUR line only
- Direct connection gives the cleanest, longest traces
- Signal clamp traces live lines without breaking the circuit
- Depth estimation at any point along the run
How it works
- 1
Find an application point
A valve, meter, riser, pedestal, tracer-wire access, or exposed section where the transmitter can couple to the target line — the single decision that makes active locating precise.
- 2
Apply the signal
Direct connection (clip to the conductor) for the strongest, cleanest trace; or an inductive clamp around a live cable or pipe where breaking the circuit isn't an option. A known frequency is energised onto the line.
- 3
Trace and mark
The receiver follows the applied frequency along the ground, marking the route in paint or flags. Because only the target carries the signal, parallel and crossing utilities don't confuse the trace the way passive sweeps can.
- 4
Depth and documentation
Burial depth is estimated at points of interest; the located route is marked and, where requested, recorded for an as-built or utility map. GPR cross-checks where confirmation or non-conductive lines are involved.
Frequently asked
What's the difference between active and passive locating?
Active locating applies a chosen frequency to a specific line (by direct connection or clamp) and traces that line alone — precise and unambiguous. Passive locating detects signals already present on buried metal (power at 50/60 Hz, or re-radiated radio) without applying anything — fast for sweeping an area but unable to tell you which line is which. Professionals use active to trace a known target and passive to make sure nothing energised was missed.
Direct connection vs signal clamp — when do you use each?
Direct connection clips the transmitter straight to a conductor at an access point — it gives the strongest, longest, cleanest trace and is the default whenever a connection point exists. A signal clamp wraps around a pipe or live cable to induce the signal without interrupting service — essential on energised power and where no bare connection point is accessible. Many jobs use both at different points along the same run.
Can active locating trace a live electrical cable safely?
Yes — the inductive clamp is designed exactly for that: it couples a locating signal onto an energised cable without any direct electrical contact and without interrupting supply. It's the standard professional method for tracing live power and is far more reliable than trying to follow the cable passively in a corridor full of other conductors.
What can active EM locating NOT find?
Anything non-conductive with no tracer wire — plastic water mains, clay or PVC sewer, concrete ducts — because there's nothing for the EM signal to travel along. That's not a weakness to hide; it's why EM is always paired with GPR (which images non-conductive lines) and with sonde/duct tracing for drains. The honest locate uses the right tool for each line, which is the whole point of a dual-method crew.
Related EM methods
Passive EM Sweep Locating
Sweep an area for the signals buried metal already carries — live power at 50/60 Hz and re-radiated radio energy — to catch energised and conductive lines before a dig, without connecting to anything. The fast first pass that makes sure nothing live gets missed.
ViewInductive EM Locating
When there's no valve, riser, or bare conductor to connect to, the transmitter induces a locating signal into buried lines from the surface — letting a crew trace conductive utilities in areas where direct connection simply isn't available.
ViewDepth Estimation & Utility Mapping
Add the third dimension and a permanent record: estimated burial depth at every point of interest, and a marked, measured map of what's underground — the deliverable that turns a one-day locate into a lasting site asset.
ViewEM + GPR Utility Clearance Survey
The complete pre-dig clearance: passive sweep, active EM tracing of every conductive line, GPR imaging for non-conductive lines and confirmation, sonde tracing for drains, and depths at the dig point. The single survey that makes breaking ground safe — and the everyday private locate done right.
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Active EM Line Locating across BC
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Locate before you dig. Both methods. One crew.
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