Insulating Gloves in Service: Storage, Issue and Re-Test

Two clocks govern an insulating glove and they do not start together: a Class 1–4 glove is compliant for up to 12 months from the date of manufacture, and for 6 months from the date it is issued. This is what has to happen at storage, at issue, and at the six-month re-test — and why Class 00 and Class 0 are not simply exempt.

Selecting an insulating glove is a decision you make once. Keeping it compliant is a decision you revisit every six months — and that is where most sites lose track, because the two clocks that govern the glove do not start at the same time.

Two dates decide whether a glove may be used.

• From the date of manufacture: a Class 1–4 glove is treated as fully compliant for up to 12 months, even if it has never left the store.
• From the date of issue: once the glove is issued for work, its validity runs 6 months from that date.

Read together, those two sentences describe a case that catches people out. A glove manufactured fourteen months ago and still sealed in its packaging is *not* ready to issue: it has passed the 12-month window, so it has to be re-tested before it can be handed out. Equally, a glove issued today has a six-month clock running regardless of how rarely it is worn.

The in-service rules

The Class 00 and Class 0 exemption is narrower than it sounds. It does not remove the pre-use inspection, it does not remove the air-leak test, and it does not mean the gloves can sit indefinitely without anyone looking at them.

What to record when a glove is issued

The rule is only usable if the second date is written down. The date of manufacture is permanently marked on the glove; the date of issue is not. A durable issue record is what turns a six-month rule into something you can actually audit:

• the glove's class and its unique identification
• the date of manufacture, as marked
• the date of issue
• the next re-test due date
• who issued it and to whom

Do not judge a glove by its colour

Class colour conventions exist — beige, red, white, yellow, green, orange — but they come from the North American ASTM D120 convention, not from IEC 60903, and they are not a selection method. The class marked on the glove and its label is the only authority. A glove whose colour suggests one class and whose marking says another must be treated according to the marking.

Matching the glove to the environment, not just the voltage

Two independent pieces of information determine whether a glove is right for the job.

Type describes the material behaviour. Type I is natural or synthetic rubber and is not resistant to ozone. Type II may be any elastomer or combination and is ozone resistant. In a room with motors, drives or other arcing equipment, that difference matters.

Category letters indicate additional performance beyond the electrical rating: A for acid, H for oil, Z for ozone, R for acid, oil and ozone together, and C for very low temperature. A glove can carry more than one. Matching these to the actual environment is the step that is most often skipped.

Working without leather protectors

If a glove is used without leather protectors over it, the working class has to be raised by one — Class 00 and Class 0 excepted. The reason is mechanical rather than electrical: the protectors, not the rubber, are what take the abrasion.

Cuff length is specified in the same section of the standard. The glove cuff must extend beyond the sleeve of the protector by a minimum of 12 mm for Class 00 and Class 0, 25 mm for Class 1, 50 mm for Class 2, 75 mm for Class 3, and 100 mm for Class 4.

On thickness — deliberately not quoted

Thickness figures for insulating gloves circulate freely online, and they are not interchangeable. Thickness is specified by whichever standard a glove is made to, and the IEC and ASTM requirements for it differ. Rather than publish a number that may apply to a different standard, we state what the glove is made to and leave the dimension to that glove's datasheet.

A note on the standard's version

IEC 60903:2014 is the edition in general use and the one most product documentation references. A 2025 draft is in preparation; it has not replaced the 2014 edition, and documentation written against 2014 should not be presented as already superseded.

How we supply them

Our insulating gloves are manufactured and tested to IEC 60903, EN 60903 and ASTM D120. Every glove is dielectric tested before dispatch, and the batch test report is supplied with the order — which is the document an auditor asks for when they want to see what the gloves in the store were tested against.

See the Class 00–4 reference table for the full voltage, proof test and category breakdown, and the insulating mat thickness guide for the same treatment applied to matting.

Questions we get asked

Do Class 00 and Class 0 gloves ever need re-testing? Routine dielectric re-testing is not required for these two classes, but that is not the same as being exempt from checks. They still require inspection and an air-leak test before use, and voluntary re-testing remains available.

Our gloves are marked 20 kV — does that mean they are rated for 20 kV? No. That figure is usually the AC proof test voltage, which belongs to Class 2. The maximum use voltage for Class 2 is 17,000 V AC. Selecting on the proof test number rather than the maximum use voltage puts you one class below where you intended to be.

What happens if gloves sit in the store for two years? Past 12 months from the date of manufacture they are no longer treated as compliant without re-test, so they must be re-tested to the standard before they are issued.

Browse our 10 kV – 35 kV rubber insulating gloves, or talk to us about a glove programme with the test documentation included.