Swimming Pool Inspection, Safety, and Maintenance

Some free tips on the National Electrical Code, Article 680

Swimming pools, if permanently installed, must comply with Parts I and II [680.20] of Article 680. This means that the pool must have a copper equipment grounding conductor (EGC) to any cord-and-plug-connected equipment (except underwater lights). And it has to be at least a #12 wire.

With the 2011 NEC, there are now requirements for how you must install LED lighting. Previously, the requirements didn't address the DC power supply these lights use. The 2011 NEC also allows you to use Type MC cable for the feeder circuit.

Something that many installers don't understand is the bonding requirement. The purpose of bonding is to put all metallic objects at the same electrical potential by connecting them with wire. This way, there can't be a flashover due to a charge build-up. Some installers have assumed this somehow applied only to the electrical equipment. Now, think about it. You want all equipment to be at this same zero potential. And so does the NEC. So you bond all equipment.

Bonding doesn't mean driving a ground rod. The earth isn't a bonding conductor. It has far more resistance than wire does. You bond by creating a metallic path that allows electricity to get back to its source.

If it's metal, you bond it. Some places installers often overlook:

• Service panel. This typically has a ground rod, but that's for lightning protection. It does not put the panel at the same potential as other metallic objects.
• Other utilities. Gas, phone, and cable often have their own ground rods. But these rods are typically separated by huge impedance levels. Bond them per the NEC, Article 250 Part V.
• Control panel. The controls for the water pump, etc., are often in a metallic panel. This may be bonded via the wiring, but don't count on that. Run a dedicated bonding conductor to the main bonding jumper or another metallic object that is bonded.
• Ladder. Metallic ladders can store a charge.
• Fence. A metallic fence around a swimming pool area can act like the anode or cathode of a big capacitor, storing up a lethal charge. Bonding it to the other metallic objects prevents this.

Some people are really stuck on this false idea that grounding makes you safe. Their conclusion based on the false idea that electricity follows the path of least resistance. The reality is that electricity follows all paths before it, in inverse relationship the the impedances presented. That's Kirchhoff's Law of Parallel circuits, and if it were not true then you would not have a functioning cell phone or computer.