A Cut Glove, Seventy Percent Through the Job
A 2021 battery-electric sedan (355 V nominal, 403 V maximum) is in your bay for a high-voltage junction-box inspection. You inspect your Class 0 rubber insulating gloves - marked 1000 V AC / 1500 V DC maximum use, proof-tested four months ago - with a visual check and an air test, and find no defects. You remove the service disconnect, wait the OEM-specified five minutes, and verify 0.0 V from HV+ and HV− to chassis at the inverter with a CAT III 1000 V meter. Twenty minutes in, you snag the left glove on a bracket edge and put a 3 mm cut through the palm. Your lead tech says the right glove is still good and that double-gloving over the cut will get the job finished before lunch. The vehicle is 70% reassembled and the customer is waiting in the lounge.
1. State your immediate actions and what must happen to the damaged glove. Explain whether double-gloving over the cut is acceptable.
Read the worked answer
Stop work and control the hazard first.
- Withdraw hands from the enclosure, withdraw the tool, and step back from the pack.
- If the pack is still open and energized, complete de-energization (service disconnect out, wait time observed) and re-verify 0.0 V at the work point before doing anything else - an interruption means the absence-of-voltage check must be repeated when you return.
- Remove both gloves; keep leather protectors on only long enough to handle the rubber safely.
The cut glove is finished.
- A 3 mm cut through the rubber is a full-thickness dielectric breach. Rubber insulating gloves cannot be patched, taped, or glued, and the damage is not rated down to a lower voltage.
- Tag it, remove it from the tool crib, and destroy it per your employer's program so it cannot be picked up later. Record the removal in the glove inspection log and on the repair order.
- Replace with a matched pair from current stock: within the proof-test interval, air-tested and visually inspected.
Double-gloving is not acceptable. The second glove is a second, independent barrier rated for the same voltage - it is not a repair. Two compromised or doubled barriers do not restore a known-good single barrier, and the added bulk degrades dexterity, which increases the chance of a second breach. Leather protectors are mechanical protection only and have no dielectric rating.
Also flag the bracket edge so the next technician does not repeat it.
2. Your lead tech argues Class 0 is overkill and that Class 00 gloves (500 V AC / 750 V DC maximum use) are cheaper and adequate for a 403 V system. Evaluate the argument.
Read the worked answer
He is not automatically wrong on the voltage arithmetic, but he is choosing the wrong criterion.
- Class 00 carries a DC maximum use voltage of 750 V, so a 403 V DC system does sit below it. Class 0 (1000 V AC / 1500 V DC) is one step of margin above.
- The AC and DC ratings are separate. A "500 V" figure is the AC number and cannot be carried across to a DC bus. Anyone quoting the AC rating for a DC pack is making an error.
The decision is not settled by that, because in a real shop three other things govern:
- The OEM service information for this vehicle, which typically specifies a glove class and an insulated-tool rating. Deviating from published procedure is a documented risk and a warranty/liability problem.
- The employer's written program and arc-flash risk assessment, which may set a higher floor than the minimum standard because of available fault current, transients, or task-specific rules.
- Consequence of failure. Class 0 buys headroom for switching transients and for measurement error. A 400 V DC system can sustain an arc; margin is cheap, and gloves are the cheapest safety item in the building.
Cost is not a criterion. A glove that passes inspection and fails in service costs far more than the price difference. Stay with Class 0, keep the proof-test interval current (typically every six months of use), and re-test after any suspected damage or chemical contact.
3. What PPE beyond gloves does this task require, and what determines it? Be explicit about what you can and cannot determine from the information given.
Read the worked answer
Required on top of the rubber gloves:
- Leather protectors worn over the rubber gloves - required for mechanical and abrasion protection, not optional.
- Arc-rated face protection (face shield plus balaclava or equivalent) and arc-rated clothing, selected from the incident energy on the equipment label or from the employer's task-based PPE table if no label exists.
- Insulated tools rated for the system voltage; no jewelry; meter, leads, and probes rated CAT III (minimum) for the DC bus and inspected before use.
What determines it, and what I cannot determine here:
- The PPE level is set by incident energy, which depends on available fault current and protective device clearing time - neither is in the scenario. So I cannot state a calorie rating from this information alone.
- 400 V DC is above the level at which a self-sustaining arc is a realistic concern, so "low voltage, low risk" is the wrong frame. Safety glasses alone are eye protection for chips, not for an arc.
- If the equipment is unlabeled, the correct move is to default to the employer's PPE category table for the task and get the arc-flash study, not to guess low.
Document the PPE used and the basis for the selection on the repair order.