Help with Whole-house Surge Protection


Chuck wrote to Ask-a-Pro

Is there a whole house surge arrester available that is hard wired to your main panel to offer surge and lighting protection up to say maybe 15,000 amps that also offers a lifetime warranty? I want to get something to protect all my stuff (theater, other TVs, computers, etc.) that clamps at no more then 10% over rated voltage (130 volts) and reacts in less than one nanosecond. Does it exist?

PFPower Responded:

Main or sub- service panel surge protectors/suppressors do exist, but not for the application that you’re speaking of. Service entrance protectors do a great job of attenuating surges before reaching your home’s major appliances (specifically 240VAC) but not your precious electronic widgets and gadgets. Because your connected electronics run on 120VAC and use low voltage wiring to interconnect to one another, you need application specific “point of use” protection to clamp off surges at 135VAC in a fraction of a second, and clamp off low voltage surges going in/out on coaxial, Ethernet and telephone wiring.

Ken Dooley of Schneider Electric also added:

SquareD offers the Surgebreaker product, part# SDSB1175C. This is a hard wired, Whole House Surge Protective Device to be installed to the main panel to protect home electronics, appliances and advanced lighting systems from line surges caused by lightning and other sources.

The product offers greater than 15,000 amps protection, at 80,000 amps per phase AC line protection for single-phase 120/240VAC applications. In addition, the product includes protection for four telephone lines and one Coax/Satellite line.

The 130 volt “clamping” value posed in the question is a problem because 130 volts is considered the higher end of normal voltage. This can be confusing due to 2 or possibly 3 different voltage referenced values associated with surge protection devices.

The first value would be MCOV (Maximum Continuous Operating Voltage) which is typically listed on the product label as the voltage at which the protection device begins to “turn on” and starts to suppress impulses exceeding nominal voltage. In panel mounted surge products, it is highly unlikely you will find any product that “clamps” when it sees 130V, as this voltage is a normal fluctuation in line voltage due to swells and sags, and would be considered by definition as temporary over-voltage, not a transient voltage or surge. In this product category it is more likely the MCOV is listed as 150V. You are more likely to have seen a 130V MCOV rating on older plugstrip devices using lower rated surge components, but never a 130 volt Clamping voltage…

The second value more correctly associated with the term “clamping” and absent from the question is current referred to as the VPR (Voltage Protection Rating). This is the label value recognized by the industry as the clamping value, as established in UL 1449, 3rd edition. Under current UL testing requirements, the lowest VPR or clamping voltage you are likely to find on a panel mounted surge product is 500 or 600V. This value represents the residual or follow on voltage allowed downstream when the device is subjected to a surge impulse of 6000 volts, 3000 amps as defined by UL. That’s a pretty good sized impulse. One also needs to remember the larger the surge the higher the residual let through voltage.

To ensure the highest degree of line surge protection for sensitive electronics, best practice is to “layer” or “cascade” additional surge protection devices at the point-of-use. This is where high quality surge suppression power strips provide the most benefit. The panel mounted surge protection devices are meant to remove the majority of the initial surge energy. The power strips further reduce the remaining surge energy to more acceptable levels.

Finally, measuring the response time of a product as reacting in less than 1 nanosecond (billionth of a second) can be misleading. Surge events happen in terms of microseconds (millionth of a second) and quality surge protection devices are designed to react within the required time. Individual components within the surge device are typically rated for nanosecond performance, but a protection device as a whole can not respond in less than a nanosecond, nor does it need to.

The panel product carries a 3 year product warranty, with a $25,000 downline connected equipment warranty. Implementing a cascaded protection approach with APC brand surge suppression plug strips will add additional downline connected equipment warranty value


Some more information on residential surge protectors here.

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