Arc Flash Clothing,  provides the layer of protection between you and the heat leaving an electrical enclosure.  An Electrical Injury during an explosion caused by equipment failure or other Arc Fault can cause serious Electrical Burns.  Arc Flash Clothing is rated in calories per centimeter squared.  See Hazard Risk Categories in NFPA 70E.  The goal of the Arc Flash ppe, including electrical gloves is to limit your injury to a second degree burn, reversible damage.  

In order to determine what Arc Flash Clothing should be worn while performing electrical work you must know the hazard level, amount of incident energy, at a piece of equipment.  To determine the incident energy level, an arc flash analysis must be performed.  Without an arc flash analysis you should use the table 130.(C) 9 provided in NFPA 70E.

To understand more, and to be considered a Qualified Electrician, you should take NFPA 70E Training.