For a variety of reasons, I often wear disposable nitrile gloves when working in the shop. We do far more wood, metal and plastic work than electrical work, so the primary reasons to wear them are to avoid ordinary dirt and grime, and also protection from splinters, adhesives, paint, grease, etc. However, it has occurred that they may offer some protection from inadvertently touching energized conductors and components of voltages 240 and under. I would never deliberately touch an energized conductor or component likely to have more than 12 volts, gloves or no.
So I did a literature search on the subject and found that it's a topic dear to those who use cardiac defibrillators. Chest compression is a valuable procedure in cardiac resuscitation, but it has to be interrupted when a defibrillator is applied to avoid shock to rescue personnel. It's the "Clear!" scene in countless dramas. So, the question was whether ordinary exam gloves provide sufficient protection to personnel to allow compression to continue during defibrillation. The answer is no, as the studies cited below illustrate. Class 1 gloves or an insulating blanket have to be used. Most ambulances and hospitals don't have these, so "Clear!" is still the common procedure.
However, defibrillators spew out 1000-5000 V, whereas ordinary residential and light commercial mains are 240 V or less. Do disposable nitrile gloves provide protection for these voltages? Yes, but with qualifications. First, the gloves have to remain physically intact, but they are easily punctured. Put one on and push a tuft of stranded wire against your finger. You'll probably feel a copper point or two on your skin. Second, while manufacturers may give a limited guarantee of lack of holes for new gloves intended for the medical market, there is no guarantee or specification for electrical resistance. The gloves are intended to prevent transmission of microbes, not electrons.
How is resistance of a glove measured? For details, read the cited articles. Briefly, there are two techniques. One is to put the glove on a metal hand and lay it on a piece of sheet metal. Then measure resistance. The other is to fill the glove with saline and put an electrode in it, then place the glove assembly in a saline bath with an electrode. Then measure resistance between the electrodes.
In study #1 below, which examined nitrile and gloves of other compositions (vinyl, latex, etc.), in no case was the current more than 1 mA at 500 V or less. Study #1 used the metal hand technique. In study #2, the worst case was 60 k? using the saline technique. At 240 V, this would be only 4 mA.
So, I will continue to wear nitrile gloves when dealing with live electrical circuitry but try to behave as though I have bare hands. It's important to guard against a psychological effect called risk compensation by actuaries. It's the tendency of people to engage in riskier behavior when they know a safeguard has been added to a system.
In the US, the Occupational Safety and Health Administration rule for protective equipment for voltages 300 and less from any distance is "Avoid Contact." In other words, no gloves or other protective equipment required. Individual states and localities and other countries may have more stringent rules.
I've watched hundreds of electronics videos on youtube, and it's uncommon to see gloves of any kind worn when the presenter is working with exposed mains or other high voltages.
Citations:
1. Will medical examination gloves protect rescuers from defibrillation voltages during hands-on defibrillation? Sullivan JL, Chapman FW. Resuscitation. 2012 Dec;83(12):1467-72
2. Do clinical examination gloves provide adequate electrical insulation for safe hands-on defibrillation? I: Resistive properties of nitrile gloves. Deakin CD, Lee-Shrewsbury V, Hogg K, Petley GW. Resuscitation. 2013 Jul;84(7):895-9.
Two sections of abstract of above article:
Methods:
Clinical examination gloves (Kimberly Clark KC300 Sterling nitrile) worn by members of hospital cardiac arrest teams were collected immediately following termination of resuscitation. To determine the level of protection afforded by visually intact gloves, electrical resistance across the glove was measured by applying a DC voltage across the glove and measuring subsequent resistance.
Results:
Forty new unused gloves (control) were compared with 28 clinical (non-CPR) gloves and 128 clinical (CPR) gloves. One glove in each group had a visible tear and was excluded from analysis. Control gloves had a minimum resistance of 120 k? (median 190 k?) compared with 60 k? in clinical gloves (both CPR (median 140 k?) and non-CPR groups (median 160 k?)).
3. Do clinical examination gloves provide adequate electrical insulation for safe hands-on defibrillation? II: Material integrity following exposure to defibrillation waveforms. Petley GW, Deakin CD. Resuscitation. 2013 Jul;84(7):900-3.
4. Achieving safe hands-on defibrillation using electrical safety gloves – A clinical evaluation. Charles D. Deakin, Jakob E. Thomsena, Bo Løfgrenb, Graham W. Petleye. Resuscitation. 2015 May;90:163-7.
Mike in California