The Generator Interlock Kit

The generator interlock kit is a device that is designed in allowing safe powering of the home using a portable generator when there is a power outage. It is a cheap alternative as compared to installing a dedicated transfer switch. The kit attains the same operation by applying an external interlock upon the existing breaker panel. this enables the main breaker to be switched on or a particularly designated load breaker to be switched on. But it prevents both breakers from being on at the same time. The interlock load breaker is used as the backfeed breaker, as the generator is directly connected to this breaker or can be connected to it via an inlet.

Under normal conditions, the main breaker is always on, allowing power from the external mains to flow into the panel, and the backfeed breaker is off, breaking the generator off from the circuit. The external mains always feed the panel while the panel cannot backfeed the generator. There should never be any backfeed to the generator as it has no need and it might damage the generator.

When the generator is running, the backfeed breaker comes on allowing power from the general to flow into the panel, and the main breaker is switched off blocking the external mains. The generator works to feed the home by backfeeding the panel while the panel cannot backfeed the external mains. Backfeeding the external mains is risky and illegal as it can lead to electrocution of line workers, start a fire as well as overload or damage the generator. 

The operation

A generator interlock kit is connected on the floor cover upon the home’s breaker panel. It has two sliding steel or plastic plates that are held together using three bolts depending on the brand. When they are moved down the plates prevent the generator backfeed circuit breaker while allowing the main breaker to maintain its ON position. While when it is moved up, the generator backfeed breaker might be turned on, and the main circuit breaker is switched off. The generator backfeed circuit breaker is the connected to the generator inlet that is connected to the exterior of the structure. There is a short cord connecting the generator to the casing inlet normally via a twist-lock as well as the socket.

The advantages

  • Just like the transfer switch, the interlock kit allows the generator to power the panel and all of its entire circuits depending on the generator’s maximum load capacity; and not just the corded appliances only.
  • The interlock kit does not need an independent panel to function, it can be connected directly on the home’s main breaker panel so long as it has any unused double pole breaker slot that is available.
  • The generator interlock kit which is sometimes referred to as a transfer switch removes the need for using extension cords in powering the appliances.

The disadvantages

  • Although most of them are test by an independent lab to meet the UL standard, they normally have no UL Listing mark. This means some electrical inspectors reject the use of these interlock kits.
  • To remove the electrical panel’s cover might enable the generator backfeed breaker to switch on while the main is still on, this will energize the power lines or overload the generator in case the generator is connected.
  • In some of the applications, connecting an interlock kit needs drilling holes within the panel cover, and this means that once it is installed it cannot be isolated.
  • Due to the fact that the main breaker is switched off, he homeowners have no way of identifying when the utility power is restored unless you manually turn the generator’s breaker off while the main breaker on. But there is at least a single device that can produce an audible alert that indicates that the utility power has been restored.
  • To install an interlock kit needs two or more spaces within the existing panel.

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