Electrical Surge Protection - Further Reading

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How to Protect Pool Equipment from Electrical Surges

In the simple old days pool equipment had few electronics in them. Pumps were controlled by mechanical timers. Heaters used knobs and rheostats for temperature control. Pool control systems used relays to turn equipment on and off. The equipment could handle an electrical surge without much, if any, damage.

Now most pool equipment has complex electronic controls that are sensitive to electrical surges. Variable speed pumps have electronics in the control head; heaters have electronic touch panel controls; SWCGs have electronic control boards; automation panels have data communication electronics. Having an electrical surge hit your pool equipment can cause thousands of dollars of damage.

What Causes Electrical Surges

Electrical surges on your power lines can come from the incoming power service or from external electrical such as lightning.

A failure on the electrical power grid, such as a car knocking down a power line, can cause a sudden power surge into the nearby houses until the safety systems cutoff the power.

Lightning does not need to strike the power lines[1] to cause a surge in your power line. The electromagnetic fields (EMF) caused by a lightning strike nearby can cause high voltage surges on your electrical wiring anywhere in or around your house. Such a lightning EMF does not need to enter through your main power entrance.

Types of Surge Protectors

A good surge protector should have indicator lights showing that it is operational. Surge protectors can handle a fixed amount of electrical power that it can shunt to ground before it is no longer effective. Depending on the power of the surges the protector needs to handle it may be able to take a few hits or it may be rendered inoperative after it does its job once.

You need to check your surge protectors operational status after any major surge or storm. When a surge protector indicates it is not operational it needs to be replaced. Surge protectors cannot be repaired.

External Surge Protector

The Siemens FirstSurge[2][3] device can be used in any panel since it connects directly to both line wires, neutral, and ground. That allows the FirstSurge to dump a surge directly to the ground.

The Siemens FirstSurge protector comes in three models with different surge capacities:

  • FirstSurge™ Power (FS60) - 60,000 Amp Surge Capacity
  • FirstSurge™ Plus (FS100) - 100,000 Amp Surge Capacity
  • FirstSurge™ Pro (FS140) - 140,000 Amp Surge Capacity

Another surge protector with fewer features is the Square D by Schneider Electric HEDP50/HEPD80[4][5].

An external surge protector should be installed as close to the panel as practical. For every extra foot of wire between the panel and the device, you lose 175 volts of protection! As short and direct as possible gives more protection.

The best commercial grade external surge protectors have 3 Stage Commercial Grade Notification including an audible alarm and Ground Reference Monitoring (GRM). GRM notifies you if a rare safety hazard exists due to a compromised electrical system neutral to ground bond.

Integrated CB and Surge Protector

The Siemens QSA2020SPD[6] is an example of an integrated Circuit Breaker and Surge Protector. Those type of integrated CB and surge protectors are intended to be installed at the service entrance, where the ground and neutral are combined, not at a sub-panel.

Siemens describes the QSA2020SPD as a "incoming service entrance surge protector."

The Siemens QSA2020SPD connects to both buss stubs, and the neutral via a wire. It will clamp the voltage to all other breakers in the panel so all the downstream circuits will be protected. This particular surge protector will trip the breaker on the circuit if the device fails after suppressing a surge. This will notify you that the protector must be replaced. The breaker function will still work once the OK light is out, but there is no surge protection on that phase.

Do not install on a refrigerator, freezer or sump pump circuit as it will trip if it stops a large surge.

It is considered good practice to install the surge protector as close to the top of the panel near the "main disconnect" as possible which places it as close as possible to where the main power feeds the panel. However placing it anywhere in the panel will provide some protection.

Snap Into CB Panel Surge Protector

Surge Protectors are available that snap onto the bus bar of a circuit breaker panel. They require two adjacent CB slots to connect to both hot legs in a CB panel. This type of surge protector has a white wire that connects to the neutral bus to drain any surges.

The Schneider Electric Homeline HOM2175SB Surgebreaker Surge Protective Device (SPD)[7] is an example of such a device.

The HOM2175SB Instructions say:

NOTE:This device is not suitable for installation on 120 Vac single-phase, two-wire systems.

This SPD will provide surge suppression for most secondary distribution wiring, but may not suppress surges for solid state or electronic equipment from all lightning-induced or other large power surges.

NOTE:Use on solidly grounded systems only.

This type of surge protector gives limited protection and may be suitable for use in a main service entrance panel. Since it does not have a ground connection and dump any surge directly to ground it is not recommended to use in an outside pool sub-panel/load center.

Where Can a Surge Protector be Placed?

It is good to have a surge protector at the service entrance of your main electrical panel. This protects all the electronics in your house from surges through your electrical utility power feed.

A surge protector at the main service entrance will protect your electronics from a lightning strike surge coming in from your main electrical feed. However lightning EMF voltage can enter through any wiring around the house, especially if it is outdoors like pool electrical panels and equipment are.

For that reason, even if you have a surge protector on your main service entrance you should also install a surge protector at the entrance of your pool sub-panel/load center

Main Service Entrance Panel

At the main service panel either an external surge protector or a surge protector that snaps into CB positions in the panel can be used.

The main service panel should be the only point where the neutral and ground is connected in house wiring. The surge needs to be dumped to a close ground. The "Siemens QSA2020SPD Whole House Surge Protection with Two 20-Amp Circuit Breakers for Use Only on Siemens Panels" makes use of that with a connection only to the neutral and expects there to be the ground connection for the surge to be dumped to.

Pool Sub-Panel or Automation Load Center

An external surge protector, like the Siemens FirstSurge or Square D HEDP50/80, should be installed where the power lines, neutral, and ground enter the sub-panel/load center.

Installing an integrated CB/Surge Protector like the QSA2020SPD or Square D HOM2175SB in a sub-panel is not recommended and will send the surge onto the neutral bus bar and all the neutral lines and basically into any 120V equipment and back into the house electrical system.

Surge protectors with direct connection to the ground are more likely to provide the protection you are looking for in outdoor pool electrical sub-panels.