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Here are 7 Steps to Install a Generator Interlock Kit (Legally)

A generator interlock is a crucial safety piece you can install as a substitute for a transfer switch. It ensures you safely switch the emergency power on and off while preventing back-feeding the utility line. However, the device must be installed correctly and according to local electrical regulations. So, how do you install a generator interlock kit legally?

It all starts by checking in with your local electrical regulatory body to inquire if you need a permit and an electrical license to do the modifications. With the permit and license uncertainty out of the way, you can get your tools ready and follow the installation steps discussed here.

According to National Electrical Code® and National Fire Protection Code®, you need to be a qualified electrician to make any electrical modification, including installing a generator interlock kit. If you’re not qualified for the job and have the proper permit for installing the kit, hire an electrician qualified to handle the task.

How to Install an Interlock Device (Steps Involved)

What do you need?

  • Generator Interlock Kit
  • Phillips screwdriver
  • Battery-operated drill
  • 5/32 drill bit
  • 1/2″ woodblock

Step 1: Get the Paper Ready and Inspect the Device

Are you qualified to handle electrical work? Do you have the proper documents? As mentioned earlier, you need a permit for installing and making any modifications to the service panel. You also have to make sure the interlock device you’re buying is UL listed as stated under NEPA® regulations for it to be legal.

Step 2: Getting Your Panel Ready

Take your new interlock kit, place it on the panel cove to mark where the generator breaker needs to be. Typically, this would be the spot where the interlock sliding place lands.

If you don’t have the generator breaker installed there or installed at another spot, it’d be best to change it. While doing so, make sure the sliding plate keeps it off when the main power breaker is on.

Placing it is easy; there are four dimpled spots on the panel around the main breaker that is where you will dig the holes for supporting the device.

So, for starters, place the interlock devices there to sit on these dimpled spots and allow the metal place to slide.

Shut the mains off and the generator to see if the plate slides up to block you from switching on the mains breaker. If it works, you are up for the next step – drilling.

Step 3: Remove the Cover

Open the panel door. Do you see six screws holding it? Unscrew them using a Phillips Screwdriver and place the panel door on a table or a bench.

Step 4: Drill the Holes

Take your drill and a 5/32 drill bit. Depending on your panel design, you might use the inside mounting holes, and that’s why interlock kits come with two sets of screws, the shorter ones and the longer ones. The longer screws are for inside mounting, while the shorter ones are outside mounting.

Place two wood pieces in the space between the cover and the panel door to prevent you from drilling all through. Using the drill with the 5/32 drill bit, drill the four pre-dimpled spots.

Step 5: Mount the interlock bracket

Using a 5/16 nut-driver, attach the generator interlock bracket to your panel by threading in the screws or bolts from the inside of the cover. That makes it tough to remove the bracket easily. It’d require you to remove the panel doo to access it.

Note: the law requires you to follow the given installation instructions, which would be perfect since these interlock kits come in different designs.

Step 6: Reinstall Panel Cover

With the interlock kit bracket mounted, it’s time to reinstall the breaker box door using the screws you unscrewed earlier.

Step 7: Stick your Kit Instructions

Before calling it a day, you must remember to stick the instructions somewhere on the panel – a sizeable yellow instruction manual and a small white sticker.

The large yellow stick contains the instructions on how to operate the interlock devices, while the small white sticker is for easy identification of the manual interlock generator breaker.

Place the sticker instructions somewhere everyone can easily see. You could stick the yellow sticker on the panel door from the insider and the white sticker next to the generator breaker.

Why Install a Generator Interlock Kit (Legally)

The primary purpose of installing a generator interlock kit is to disconnect the home main utility line before engaging the generator backup power line as required by law.

You cannot connect your generator through the main utility breaker line without using an interlock kit or a transfer switch. Doing so might land you a hefty fine or jail term for not following generator home connection regulations. You might get in more trouble as you will be back-feeding the utility line, something that can cause electrification and damages to your appliance.

Installing the transfer switch requires you to follow the strict guidelines and ordinances mentioned above to ensure the device is installed right and correctly by a person who understands the electrical system in your home.

And as I mentioned earlier, it is a safety measure that helps prevent damage to your generator and your connected appliances when the main power gets restored.

It also rules out the potential danger of electrocuting any service personnel working on the home electrical system when the generator back-feeds the main utility line.

A transfer switch reroutes essential circuits to a secondary service panel, where a transfer switch can disconnect from utility power before connecting those circuits to the generator.

What to Keep in Mind before Installing a Generator Interlock Kit

Now that you know generator interlock kits are legal, have you considered installing one? Not so first! There is a list of things you need to keep in mind before installing one:

  • The first thing is; if you do not follow the strict guidelines listed above, with one requiring the device installed by a licensed electrician, your installation wouldn’t be legal.
  • When you engage in the generator mode, you will need a way to know when the power is restored. It’d be best to install a ‘utility power back alert’ if your generator interlock device doesn’t come with one.
  • Even though generator interlock device installation is simple, your electrical panel might need a few modifications to fit it. So, don’t be surprised if your electrician suggests it.
  • It’d also be best to ensure there are enough circuit breaker spaces in the current panel.
  • In a standard interlock kit, there is nothing to prevent you from turning on extra circuit breakers. This can overload your generator. Mark the essential appliances and make sure their total wattage ratings don’t overload your generator, a situation potential of damaging your unit.

Related Questions

Are generator interlock kits legal?

Yes, they are – so long as they are UL listed and installed as per National Electrical Code® and National Fire Protection Code®. According to these ordnances, the device must be installed by a qualified electrician; the installation must be done according to the manufacturer’s instructions and the manufacturer’s information provided on-site for inspection. If you install yours while following all these regulations and requirements, you will have installed the interlock kit legally.

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Sharif Gen

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