Anticipating the need to extinguish a predictable Ground Proximity alert due to an unusable GS below 1;100 MSL; the Captain of a CRJ inadvertently pushed the left engine fire discharge button which is similar in appearance and in close proximity with the Ground Proximity alert light.

Narrative

I inadvertently discharged the left engine fire bottle after landing. The ILS XX approach; chart 11-5; notes read: 1. VGSI and ILS glidepath not coincident. 2. GS unusable below 1;100 FT MSL. The notes allude to the fact that a Glideslope Caution is occasionally generated on short final to the runway while on the proper visual glidepath. This was briefed and anticipated; however; below 1;100 FT on final; I inadvertently selected the wrong switch light to cancel the Glideslope Caution; instead depressing the LH ENG FIRE PUSH immediately to the right of the GND PRX on the pilot's glare shield. Once the initial error was made; our proximity to the runway and requisite focus outside the cockpit as well as in; hampered immediate recognition of the error; because it was totally unexpected given what I assumed had been a proper selection.On the landing roll; the First Officer stated that the thrust reverser's were not deploying. The Left reverser indicated amber and left reverser unlocked caution was displayed on the EICAS. Also displayed was the ENG BTL 1 LO caution! Suddenly it dawned on me while decelerating that I must have responded to the switch light in my periphery by depressing it thinking it was a lit GND PRX switch light. After transfer of controls we cleared the runway and--after flows and receipt of taxi instructions--secured the left engine; having realized that this condition had been self-inflicted and no actual fire condition existed. Dispatch and Maintenance were notified once in the gate and I stuck around to brief the outbound crew and assist as required. My primary attention at this stage of the approach was given to monitoring the approach; the preceding aircraft for our runway; and the aircraft holding in position on intersecting left runway. However; the primary contributing factor was the lack of any panel lighting on this portion of the glareshield making it hard to visually acquire the GND PRX button. I will personally review our SOP and switch light placement to avoid inadvertent selection in the future; will look before I select and will always positively identify. Contributing factors: Engine Fire Protection switches placement and commonality with other switch lights. Inadequate panel illumination.