Generator Interlock Kit vs Transfer Switch vs Meter Collar
Why you need one at all
Plugging a generator into a wall outlet or connecting it to a panel without a transfer mechanism can send power back onto utility lines (backfeeding). That is dangerous for utility workers and is not permitted by electrical codes. Every safe connection method makes sure the home is disconnected from the grid before backup power is connected.
Comparison
| Method | Best for | Utility approval | Notes |
|---|---|---|---|
| Interlock kit | Portable generators | Not usually needed (inspection by local authority) | Mechanical plate on the main panel; you switch circuits manually. |
| Manual transfer switch | Portable or small standby generators | Not usually needed | Separate switch next to the panel; backs up selected circuits. |
| Automatic transfer switch (ATS) | Whole-home standby generators | Not usually needed | Switches automatically when grid power fails; may be service-entrance rated. |
| Meter collar | Batteries, some generators | Required — installed at the utility meter | Fast install with no panel rewiring, only where the utility accepts the device. |
Which one should you choose?
Start with your utility: if it accepts meter collars, ask your installer to compare a collar with a conventional switch. If it does not, a transfer switch or interlock kit installed by a licensed electrician and inspected under your local code is the standard route. See meter collar rules and your utility's page.
Frequently asked questions
Is a generator interlock kit legal?
Listed interlock kits are widely accepted under electrical codes when installed on a compatible panel and inspected. Your local building department makes the final call, so pull a permit.
Do I need utility approval for an automatic transfer switch?
Usually not, because it is installed on your side of the meter. Some utilities still ask to be notified about standby generators, and your local building department will require a permit.