A power supply's power consumption is measured in watts and refers to the maximum amount of power it is capable of delivering. For best results, choose a power supply that offers a minimum of 20% wattage overhead for your application. Wattage overhead ensures that your project will function correctly, extends the life of the power supply, and offers greater design flexibility by allowing for project expansion.

Water resistance indicates how a product will perform under various environmental conditions. Standards organizations like the IEC, UL/ETL, and NEC (National Electric Code) have multiple designations for water resistance. Which one is important to you will depend on your application.

• Non-Weatherproof—This designation is for products used in applications that will not come in contact with water. You may see terms like IP20 or "Suitable for Dry Locations."
• Weatherproof—Products with this designation may have occasional contact with water/humidity/condensation. They can typically be used indoors and in protected outdoor applications. "Suitable for Damp Locations" and IPx3/IPx4 will fall into this category.
• Waterproof—These products may come in direct contact with water, and some ratings indicate that they can be fully submerged or cleaned with high-pressure water spray. "Suitable for Wet Locations" or an IP65 or above rating will typically accompany these products, which are intended for outdoor use.