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Correct installation for surge protection

Installation is key to the performance of any surge protector. Ensuring that it is going to work effectively is just as important as the purchase itself. 

All surge protectors have a value of measured limited voltage, known as the let through. This is the voltage the SPD (surge protection device) cannot absorb and gets shunted to the ground system. Let through values differ based on the testing method used and the size of the unit. To get these values, units are tested using 6 inches of lead length. If a surge protector has a let through value of 1000V every additional inch of lead length adds 25V of let through. So if you had a 10 ft lead length the let through would increase from 1000V to 3500V exposing customers equipment to the effects of a large surge.

We are often asked: Does it need to be in breaker spots 1,2 and 3? The answer is no. A surge happens in a nanosecond so the electrical bus in the panel experiences the surge at the same time. This is why we need to ensure the shortest lead lengths possible. The goal is to be as close to the neutral bar as possible. We can make a ground lug anywhere on a panel, but we want to ensure the breaker spots are as close to the neutral to keep lead lengths the same length.


Another misconception is when new electrical installations take place they must look clean and neat. Of course, we want our installation work to look good. However, an SPD can be mounted upside down and is still going to work. It does not need to be at a perfect height to be pleasing to the eye. Innosys’ concern is to ensure that the investment does its job. This is why we urge our customers to use the available free services we provide, including both pre- and post-installation inspections. 

What is the breaker or disconnect needed for install? Every manufacturer has different allowable overcurrent protection devices for their SPDs. Innosys ensures we provide the proper OCPD sizing recommendations for each application based on the location and kA rating of the SPD.

Always use a licensed professional electrician

Innosys takes great care in the correct installation for Surge Protection. We make certain that every SPD is properly installed. An improperly installed SPD will not perform at its maximum efficiency, leaving your facility’s systems vulnerable. It is recommended that companies and institutions take proactive steps to protect against the damaging effects of electrical surges and spikes. Insisting that surge protection is a key part of the installation process for every new electronic system is vital. If that is not possible, the alternative is to install surge protection as an addition to existing systems. The relatively low cost of installing surge protection makes it a budget-conscious solution that delivers a tangible reduction in operational risk. Bear in mind that achieving correct installation of commercial or industrial SPDs is not a DIY project. All hard-wired electrical surge protective devices must be installed by a licensed professional electrician.

It is equally important that field wiring (unprotected wires) and the protected wiring occupy separate conduit feeds. When unprotected and protected wires occupy the same conduit, surge energy can be induced on to the protected wiring and completely bypass the SPD.

It is strongly recommended that a grounding bus bar be installed to terminate SPD ground wires to existing electrical grounding leads. This ensures a solid mechanical connection of all grounding wires.

Schedule a free on site evaluation from Innosys Power to make sure your facility’s surge protection units are correctly installed.