FAQ
TL;DR: Field tests show 45 mm max reliable live-wire depth (±5 mm) for budget wall scanners; “you have to learn to understand it” [Elektroda, zdzisiek1979, post #9206898] SKIL 550 and Brennenstuhl WMV Plus give 60 % fewer false alerts than early Bosch DMF/GMS units [Elektroda, 10603165; 16163319].
Why it matters: Drilling one misplaced hole can cost far more than a properly-chosen detector.
Quick Facts
• Bosch GMS 120: factory 50 mm live-wire spec, users confirm ~30-45 mm real depth [Elektroda, 10605509].
• SKIL 550: street price ≈ PLN 250, 9 V 6LR61 battery, dual metal/AC modes [Elektroda, 16163319].
• Brennenstuhl WMV Plus: ~PLN 100, basic metal/AC detection, fewer false beeps than Bosch DMF 10 [Elektroda, 10603165].
• Fluke 2042 set: ≈ PLN 1 500, professional transmitter-receiver pair, finds breaks up to 400 mm deep [Elektroda, 14489015].
• Bosch DMF 10 Zoom: ±50 mm position error on shallow cables, edge-case miss at 40 mm depth [Elektroda, 10602523].
1. Which sub-PLN 500 detector gives the best balance of accuracy and price?
User reports rate SKIL 550 highest under PLN 500; it distinguishes live wires and metal with moderate false alarms [Elektroda, 16163319].
2. How deep can the Bosch GMS 120 reliably detect a live cable?
Multiple owners record consistent detection only to 30–45 mm, despite the 50 mm catalogue claim [Elektroda, 10605509; 11231086].
3. Why do Bosch DMF/GMS units show voltage where none exists?
High input impedance plus automatic gain boosts noise; ungrounded calibration excites the sensor, causing phantom AC icons [Elektroda, 11473125].
4. How can I cut false positives by half?
- Switch on 100 mm away from the wall. 2. Place free hand flat near the probe. 3. Slide slowly in two directions. Users report ~50 % alert drop with this method [Elektroda, 9206898; 11473125].
5. Does calibration really help?
Yes. Calibrating in air raises sensitivity; doing it near the surface sets a realistic baseline and trims noise [Elektroda, 11473125].
6. Can cheap (
Brennenstuhl WMV Plus locates 3×2.5 mm² live cables in drywall with 70 % success, beating no-name PLN 15 probes [Elektroda, 10603165].
7. Will these tools find non-energized wires or 0.2 mm UTP pairs?
Magneto-inductive scanners struggle below Ø3 mm. No user confirmed reliable 0.2 mm UTP detection [Elektroda, 11882467].
8. What professional option exists around PLN 1 000?
Fluke 2042 offers transmitter-receiver tracking, 400 mm depth, and selective circuit tracing for ≈ PLN 1 500; price is the only major drawback [Elektroda, 14489015].
9. How long does a 9 V battery last in daily use?
Typical runtime is 6–8 h continuous scanning; low-power alert appears near 7 V terminal voltage [Elektroda, 16163319].
10. Which detector survives job-site abuse?
Bosch PDO Multi endured dust, rain and drops without failure according to one contractor [Elektroda, 11775091].
11. Edge case: double masonry + tile—will detection still work?
Owners report Bosch GMS 120 loses the AC icon behind 25 mm tile plus 15 mm mortar, a 40 mm miss [Elektroda, 10605509].
12. Is the DMF 10 Zoom still worth buying in 2024?
Only if cost < PLN 200; it mis-locates shallow wires by up to 50 mm and is outperformed by SKIL 550 [Elektroda, 10602523; 11752687].