Helmet Proximity Alarms

A helmet proximity alarm is a personal safety device fixed to the worker's safety helmet that detects the electric field of a live conductor without contact and warns of a dangerous approach. As no additional equipment is worn on the arm or wrist, hands and arms remain completely free. For overhead line crews, for whom wearing a helmet is already mandatory, it is a practical way to have the alarm with them on every shift.

The helmet models are offered in the same three voltage bands as the arm-type HXA series. The "S" suffix in the model name denotes the helmet version.

Which model?

Model	Operating voltage	Alarm start distance	Typical use
HXA-6S	AC 6.6 kV – 33 kV	110 cm	Medium-voltage distribution lines
HXA-30S	AC 11 kV – 66 kV	100 cm at 11 kV	33 kV-class distribution and lines up to 66 kV
HXA-70S	AC 66 kV – 110 kV	Provided at the quotation stage	Overhead lines of 66 kV and above

In the same voltage class, the alarm start distance of the helmet version is longer than that of its arm-type counterpart: the HXA-6S warns at 110 cm and the HXA-6 at 80 cm; at 11 kV the HXA-30S responds at 100 cm and the HXA-30 at 70 cm. The HXA-6S is supplied with two holders in addition to the fastening strap.

Points to note in use

• The alarm does not replace the check for absence of voltage. Before going onto the line, the disconnection must be verified with a voltage detector, followed by earthing.
• A silent alarm does not mean there is no live conductor nearby; observe minimum approach distances in all cases.
• Before each shift, check that the device is firmly fixed to the helmet and check the battery status.

For arm-worn versions see arm proximity alarms; for all types see hot-line proximity alarms. The basics are covered in our article What Is a Proximity Alarm?.

Frequently Asked Questions

Do the helmet and arm types warn at the same distance?

No. According to the values above, in the same voltage class the helmet version alarms at a greater distance. The actual distance varies with the line voltage and ambient conditions.

Does the helmet alarm fit every helmet?

A strap and holders are used for fastening. If you tell us the helmet model your team uses at the quotation stage, we will check compatibility with you.