Office parks, hotels, sports stadiums; these massive structures often host thousands of visitors a day, few of which have any idea what would happen if the power took a dive and the lights went out. In a world full of broken emergency lights, utter chaos would likely erupt, turning tight hallways and staircases into stampeding deathtraps, ensued by panic and hopeless urgency.
Luckily, we live in a world where in most public places, particularly those with a lack of natural lighting, emergency lights are legally required. Though many major establishments, like the aforementioned hotels and stadiums, have diesel powered generators to provide temporary backup power, they're also obligated by state and/or local mandates to test their battery powered emergency lighting on a regular (often monthly) basis.
Of course, if you're the handyman responsible for fixing your building's lights, you probably already know that.
The first step to troubleshooting emergency lighting, and likely the most important is to get yourself acquainted with the accompanying manual. Though most lights share the same general similarities, they don't all operate identically, and often require different parts.
In addition familiarizing yourself with the unit, order spare parts ahead of time, and store them in a place where you'll always remember. The majority of your spare inventory should consist of bulbs and batteries, but it would be in your best interest to have an extra circuit board on hand as well.
Nine times out of ten, problems you experience from your lights are caused by simple issues. Bulbs aren't screwed in tightly enough, wire nuts are loose, ballists are going bad… if all the obvious physical connections seem to be in order, the cause is likely due to a bad battery. Before replacing the battery, however, make sure it's not the unit's charger that's the problem. The simplest way to test this is to swap the battery into a known working unit. If it doesn't charge, you need a new battery.
If neither of those steps fixes the issue, you may be looking at a problem with the circuit board, especially if you're having issues with tangential units; exit signs and remote lights are often configured to run off of a base unit. The problem may be resolved by simply opening the chassis and re-seating your connections, or it may indeed need need a new board entirely. Before diving in too far into this step, again, open up your manual, or consult a professional.
There's a whole lot more to fixing emergency lights than meets the eye, and it's imperative that you keep them in running order. Use this guide to establish the fundamentals and become intimate with you model documentation, and you'll find yourself ahead of the game.