C1 - Very low. Heated buildings with clean atmosphere. In this environment you can use untreated steel or painted steel. The C1 class includes materials that are not exposed to corrosion in normal atmospheric air. This can be: Schools; Shops; Hotels; C2 - Low. Atmosphere with little or no degree of pollution. Country atmosphere where An example of a C1 observation (it's dangerous now!) would be the cover of a consumer unit missing hence exposing live parts. Any exposed live parts such as an open consumer unit busbar or an exposed live cable end would be classed as a code 1, as it is dangerous (right now) at the time of the inspection. C2 = Potentially dangerous Like a C1 code, any issues categorised as C2 will mean the EICR is unsatisfactory until action is taken. EICR C3 meaning. Moving onto EICR C3, this code means that improvements are recommended for your electrical installation. An example could be wiring that doesn't meet the latest regulations, but that isn't a risk in itself. qNQvpnC.