Why Purchase a Surge Protective Device (SPD)?
A Surge Protective Device (SPD) is designed to reduce surge voltage, which protects equipment and reduces repair and replacement costs. Every SPD reduces the surge voltage to equipment during a surge to a voltage tested level known as Let-Through-Voltage.
Types of Protection
When discussing different types of surge protection, there are three main types:
| Type | What it does | Where to use it |
| Type 1 | Protection against direct Lightning strikes | At the mains incomer of any electrical installation where external Lightning Protection is installed, or is fed by overhead lines. |
| Type 2 | Surge Protection | At the mains incomer of any building that doesn’t need any lightning protection, and for use on any sub boards more than 10-15 meters from the main panel. |
| Type 3 | End equipment protection | On any piece of equipment where a low let through voltage is needed. |
What is the correct way to determine which size of SPD to use in a system?
SPDs are not one-size-fits-all devices, nor do the sizes of their kA rating (the surge rating) go hand-in-hand with the size of the panel. In other words, do not select an SPD with a maximum kA rating just because the panel is large.
To determine which SPD should be used for the system, you must know the reference to the ground as well as the type of voltage that is present. Therefore, a panel designer should first determine the type of electrical system in use, and then calculate the voltage reference to ground. The formula to determine this will depend on the type of system.
For example, for a single-phase system (also called a split-phase system), the line-to-line voltage is divided by two. The result is the optimal amount of volts that the SPD should have for that system.
How to choose a device
This is one of the most common issues with SPD installation. The most important consideration is for TT systems, where the device needs to be suitable.
There are a few devices on the market with may seem inexpensive compared to other devices, but if the device is not protecting both live & neutral, surges may enter your property and bypass the SPD.
This is generally a key indicator of the quality of the components used in the SPD.
Purchasing the Right Surge Protective Device (SPD).
While any SPD will reduce the surge voltage level passing to electrical equipment during a surge event, some have a Let-Through-Voltage that is too high to prevent damage, which is almost the same as having no protection at all. BRITEC offers a complete range of surge protective devices to protect electrical equipment. BRITEC Surge Protective Devices are the right choice for all businesses and homes.
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