Testing a swimming pool bonding grid
Required tools
An analog ohmmeter (meter with a needle, not digital). Available at Home Depot for $10.
A roll of wire (long enough to reach from the pool equipment pad to the furthest point to be tested)
Alligator clamps (attached to each end of the roll of wire)
Testing Procedure
STEP 1 - "Zero out" (calibrate) the meter:
Attach one of the ohmmeter leads to an alligator clamp that is on one end of the wire. Attach the other alligator clamp to the other ohmmeter lead. The meter will display a measurement (it is measuring the resistance of the roll of wire). Use the calibration dial to return the needle to zero. You are now ready to start.
STEP 2 - Testing
Disconnect one alligator clip from the meter and attach it to an exposed bonding at the equipment pad. Use the probe without the alligator clip to take readings of various metallic components, but touching it to them. The needle should remain close to zero.
remember, if you are measuring the Ohms of resistance using the 10X scale, every reading is multiplied by 10 to get the true resistance. There should be no need to use the 100X scale.
The following items should read zero ohms of resistance:
- Pool Heater
- Pool Pumps
- Any piece of pool equipment that is metal
- Pool Controller (or time clock box)
- Related circuit panels
- The internal grounding bar of all pool light junction boxes.
- The external bonding lug of the light junction box.
- The metal parts of the diving board, slide, deck anchors, umbrella sleeve, fountain heads, spillways, waterfalls, etc.
- Anything containing over 4 square inches of metal that is within 5 feet of the pool (in any direction): downspouts, hand railings, steel in the pool deck concrete, window frames, skimmer lids, deck drains, pool cover tracks, pool cover lids, etc.
- Swimming pool light niches can only be tested with the water removed from the pool. When installed the stainless steel (SS) light fixture's face ring should read zero. The following parts should also all read ZERO:
- The SS straps inside of a plastic light niche.
- The body of a SS niche.
If these components show any resistance other than ZERO their bonding is corrupt. More than likely the bonding wire is not securely connected or the continuity is broken between the niche, the junction box and the equipment pad.
BONDING is a matter of life and death.
Paolo Benedetti, SWD Aquatic Artist, Watershape Consultant, Expert Witness, International Construction Management
Contact the author at:
info@aquatictechnology.com or 408-776-8220
"Creating water as art."™
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