How to Choose a Personal Voltage Detector

A personal voltage detector (PVD) is a wearable device, usually mounted on the hard hat, that warns a worker with light and sound as they approach an energized AC source. Choosing one comes down to nine questions about your crews' voltages, current detection, alerting, nuisance alarms, emergency response, hazardous locations, battery life, fleet management, and testing standards. This guide takes them in order.

The stakes are well documented. In 2024, 130 U.S. workers died from exposure to electricity on the job, according to the Bureau of Labor Statistics Census of Fatal Occupational Injuries.

A PVD is a secondary warning. It supplements, and never replaces, testing for voltage, lockout/tagout, minimum approach distances, permits, and PPE. OSHA 1910.269(n)(5) requires employees to test lines and equipment and verify the absence of nominal voltage before installing grounds, unless a previously installed ground is present. A PVD is not built for that job. Its silence is not proof that a line is de-energized.

Start With What a PVD Can and Cannot Tell You

A PVD senses the electric field around an energized AC conductor. The closer the worker gets, the stronger the field and the more urgent the alert. That makes a PVD good at one job: warning a worker who is moving toward something live that they did not expect.

It also means the warning distance changes with conditions. The Compass Series User Guide lists the factors:

• Extreme humidity may decrease detection capability.
• Some materials shield electromagnetic fields from the detection circuits.
• Walking briskly may reduce the initial warning distance.
• Three-phase systems can create electric fields that cancel out in certain areas.
• Warning distances vary with the conductor's exposed surface area, its elevation above ground, and its proximity to other grounded conductive objects.

Because of those limits, an alert means stop and verify, and the absence of an alert proves nothing. Test any PVD against a known voltage or current source before each field use.

An alert means stop and verify. The absence of an alert proves nothing.

Nine Questions to Answer Before You Buy

1. What voltages do your crews work near?

Coverage should match the work, from service drops to transmission. Ask each vendor for the voltage span in writing, and ask whether the worker has to select a range to get it. Every range a worker has to select is a setting someone has to get right in the field.

For reference, Compass Core, Compass Pro and Compass Pro IS all cover 120 V to 500 kV AC with no range to select. Compass Pro and Compass Pro IS run one 22-setting sensitivity scale; Compass Core uses two settings from it.

2. Do you need current detection as well as voltage?

Some detectors sense voltage only. Others also alert on current, as a separate signal. Ask whether the device detects current and whether the worker can tell the two alerts apart at a glance.

All four Compass models detect both voltage and current. On Compass Series devices, red LEDs and a tone mean voltage, and blue LEDs and a tone mean current, as Understand Voltage and Current Alerts explains. Current detection also helps with handheld tasks such as tracing wires inside walls.

3. How does the alert reach the worker?

A warning only works if the worker notices it in time. Check three things:

• Where it is wornA device on the hard hat brim sits in the worker's peripheral vision. A device on a belt or in a pocket has to be heard or looked at.
• Whether it shows directionDirectional alerts tell the worker which way the source is. Compass directional accuracy is approximately ±20° to a point source.
• Whether it escalatesAlerts should grow more urgent as the distance closes. On the connected Compass models, the Max Alert distance is approximately 60% of the First Alert distance, so a First Alert at 10 ft (3.0 m) corresponds to a Max Alert near 6 ft (1.8 m).

4. How does it handle steady energized environments?

Beside energized equipment, a detector that alarms constantly reports what the worker already knows. The temptation is to turn sensitivity down or mute the device, and the Compass guidance is direct about that: oversuppressing alerts can hide real risk.

Ask how the device handles a steady field without going silent. Compass Pro and Compass Pro IS offer two adaptive modes:

• Work Zone AdaptiveSets the alert level to the field where the worker stands and holds it there. If the field grows above that level, the device alerts, with direction.
• Smart AdaptiveKeeps adjusting as the worker moves. It alerts when the worker moves toward a source and settles when they hold still.

Adaptive modes should be used only by experienced electrical professionals. Compass Core does not have them.

Also ask what the device does when it is muted. On a fixed Compass setting, a muted device in an above-threshold field still shows periodic fading corner lights. In Transit, the audible alarm and the directional indicator are off, but detection continues and the corner LEDs still escalate as the worker gets closer.

5. Does the device need to call for help?

Detection warns before contact. Emergency response matters after an event, especially for lone or remote work. Ask whether the device can raise an event on its own, and where that event goes.

Compass Core, Compass Pro, and Compass Pro IS detect impacts, falls above 6 ft (1.8 m), and arc flash, and the worker can raise an SOS with a 3-second button hold. Through Navigator, the event reaches designated responders with location and context. After an automatic event, a 30-second countdown lets the worker confirm or cancel, and no motion during an active event escalates it to worker-down. Emergency events require an active Navigator Respond subscription. Compass G2 does not raise emergency events.

Emergency workflows depend on Bluetooth and the phone's network, so ask how the system reports a lost connection. In Navigator, a worn device that has been disconnected for more than three minutes is flagged as Connection Lost, with its last-seen time and location.

6. Will crews enter classified hazardous locations?

In areas with potentially flammable gas or vapor, the device needs intrinsic safety approvals for that classification, and so does any adapter used with it. Ask for the exact markings, not a general claim.

Compass Pro IS is the Compass model that carries these approvals: Class I, Division 1, Group D, 136 °C (T3); Class I, Division 2, Groups C and D (T3); and Class I, Zone 0, AEx ia IIA (T3) Ga, with ATEX and IECEx marking II 1 G Ex ia IIA 136 °C (T3) Ga. Only approved adapters may be used in classified areas, and the Compass Pro IS User Guide Annex is the governing document for hazardous-location use.

7. Does the battery cover your shifts?

Battery life depends on how often the device alerts, so compare typical figures and ask how the device warns of a low battery. Typical Compass figures:

• Compass G210+ days (80+ hours of use)
• Compass Core and Compass ProAbout 6 days (48+ hours of use)
• Compass Pro ISAbout 2 days (16+ hours of use)

Check charging limits too. Compass Core, Compass Pro, and Compass Pro IS charge between 0 °C and 45 °C (32 °F to 113 °F) and typically reach 100% in 1.5 hours.

8. How will you manage settings across the fleet?

Settings drift when every worker manages their own device. Ask whether an administrator can set and lock options centrally, how firmware updates reach the field, and how frequency variants are handled.

• In Navigator Console, Compass Pro Configurations let administrators set sensitivity, adaptive modes, and impact, fall, and arc flash policy, and lock specific options. Changes apply once the worker confirms them in Navigator Mobile.
• Firmware updates reach Compass devices through Navigator Mobile.
• Grid frequency is built into Compass detection tuning, so 50 Hz and 60 Hz kits are separate part numbers and frequency cannot be changed in the field. Match the part number to your grid.

9. What was the device tested to?

Ask for the list of standards and certifications, and read what each one covers. Compass G2, for example, lists EN 61010-1, IEC TR 61243-6 (Type I), ANSI/ISEA Z89.1-2014 Class E (as a tested hard hat accessory), and ASTM F3283/F3283M-18, with an IP-67, flame-retardant enclosure.

Standards describe how a device is built and tested, not how your crews should use it. ASTM F3283, for example, is a manufacturing specification for high-voltage proximity alarms that detect AC voltage above 600 V on overhead power lines at 50 to 60 Hz. Its scope states that use, installation, and maintenance are outside the standard. Your written program covers those.

Compass Series at a Glance

Compass Core, Compass Pro, and Compass Pro IS are the models that raise emergency events through Navigator. Here is how they compare on the questions above.

Compass G2 is the entry-level model and the only standalone one: it does not connect to Navigator. It detects voltage and current, gives proximity and directional alerts, and does not raise emergency events. Typical battery life is 10+ days (80+ hours of use), it weighs 0.78 oz (22.1 g), and its listed part number is M01001, a 60 Hz unit. See the Compass G2 page for its specifications, and Compass Core vs Compass Pro vs Compass Pro IS for the full differences between the other three.

Questions to Ask Any Vendor

• What voltage span does the device cover, in AC volts, and does the worker select a range to get it?
• Does it detect current as well as voltage, and are the two alerts distinct?
• Where is it worn, does it show direction, and how does the alert escalate as the distance closes?
• What does it do in a steady energized environment, and what does detection look like when it is muted?
• Can it raise an emergency on its own, who receives it, and what happens when the connection drops?
• Which hazardous-location approvals does it carry, by exact marking?
• What is the typical battery life, and how does it warn of a low battery?
• Can administrators set and lock settings across the fleet, and how do firmware updates reach the field?
• Which standards was it built and tested to, and what does each one cover?
• What are the documented operating limits, and how should crews test it before use?

Frequently Asked Questions

Sources

• U.S. Bureau of Labor Statistics, Census of Fatal Occupational Injuries, Table A-9, 2024 (published February 2026): 130 fatal occupational injuries from exposure to electricity, of 5,070 total.
• OSHA 29 CFR 1910.269(n)(5), testing before grounding.
• ASTM F3283/F3283M-18(2024), scope sections 1.1 to 1.4.
• Safeguard Equipment, Compass Series User Guide (September 2026) and Compass Pro IS User Guide Annex.
• Safeguard Help Center: Understand Voltage and Current Alerts, Adjust Sensitivity and Use Transit, Adaptive Modes, Mount the Device Correctly, and Safety Disclosures and Field Use Warnings.