How to Inspect Your 240V Outlet for Safe Home EV Charging

How to Inspect Your 240V Outlet for Safe Home EV Charging

Holden Kooiker Holden Kooiker
2 minute read

Before you plug in your Smart Splitter or EV charger to your NEMA 14-50 outlet for the first time, we strongly recommend a quick visual inspection.

Take a look at your outlet and you will see brass clamps on the inside of each of the holes. With a cord plugged in, the pins from the plug head will force open these clamps and create a mechanical connection which will allow electricity to flow through the circuit. Over time, these brass pads will slowly lose their clamping force due to a combination of retaining their stretched shape and thermal expansion during use. A loose clamp will lead to increased resistance at the point of contact and eventually lead to higher temperatures within the outlet.

What to look for:
Examine the two hot/live slots in the outlet and look at the distance between the brass clamps.

  • A new outlet's clamps will be practically touching one another as the clamp has not lost any of its spring force. This outlet is good to go and will several years before you might consider another visual inspection.
  • An older outlet that is worn from use will have a large gap between the clamps. This loose outlet could potentially cause issues if it does not maintain a secure connection with the plug.

If your outlet is loose:
If you have identified that your outlet is loose and may cause increased resistance, we recommend replacing the receptacle. This is a pretty simple task that can be completed in about 10 minutes by an electrician. You can choose to use a standard or a commercial grade outlet:

  • Commercial Grade Outlets (Recommended) - Commercial grade 240V outlets are heavy duty outlets with superior clamping mechanisms and are identifiable by a larger outlet diameter. These outlets are a bit more expensive but strongly recommended for the increased safety when EV charging in your home. Common commercial grade outlets include the Hubbell #HBL9450A and Bryant #9450FR. These are not normally carried in retail stores but can be found online.
  • Standard Outlet - Installing a new standard 240V outlet will work fine and is less expensive than the commercial grade option. This can be found at your local hardware store like Home Depot. If using a standard outlet for EV charging, we recommend performing a visual inspection every few years to ensure the clamps are not becoming loose.

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