Tamper-Resistant & Weather-Resistant Receptacle Calculator
Find out whether a receptacle must be tamper-resistant, weather-resistant, or both under the National Electrical Code (NEC). Pick the occupancy and the moisture of the location and the tool applies NEC 2020 406.12 for the tamper-resistant requirement and 406.9(A)/(B) for the weather-resistant type and cover, including the four 406.12 exceptions.
How to use this calculator
- Select the occupancy or area. The seven areas in 406.12(1) through (7) require tamper-resistant receptacles; anything else does not.
- Select the moisture of the location: dry, damp, or wet. Damp and wet locations require a weather-resistant type and the matching cover.
- Confirm the receptacle rating. The tamper-resistant and weather-resistant-type rules apply to 15/20 A, 125/250 V nonlocking receptacles.
- Optionally enter the mounting height and check any 406.12 exception that applies (part of an appliance, dedicated appliance space, nongrounding replacement).
- Read the verdict: tamper-resistant, weather-resistant, both (a listed TR-WR device), or neither, with the cover requirement for the location.
NEC reference
This calculator implements NEC 2020 406.12, Tamper-Resistant Receptacles, and NEC 2020 406.9, Receptacles in Damp or Wet Locations. 406.12 lists the seven areas whose 15/20 A, 125/250 V nonlocking receptacles must be listed tamper-resistant, and the four exceptions. 406.9(A) covers damp locations and 406.9(B) covers wet locations, including the listed weather-resistant-type requirement and the extra-duty in-use cover for wet locations. The 406.9(C) bathtub and shower zone is handled by a separate tool.
Results are for reference only. Verify against the applicable adopted edition of the NEC and consult a licensed electrician for code compliance.
Where tamper-resistant is required (406.12)
The tamper-resistant requirement is written as a list of occupancies. It reaches every 15- or 20-ampere, 125- or 250-volt nonlocking receptacle in these areas, not just the ones within a child's reach, unless one of the exceptions applies.
| Area | NEC |
|---|---|
| Dwelling units, incl. attached and detached garages, accessory buildings, and multifamily common areas | 406.12(1) |
| Hotel and motel guest rooms, guest suites, and their common areas | 406.12(2) |
| Child care facilities | 406.12(3) |
| Preschools and education facilities | 406.12(4) |
| Business offices, corridors, and waiting rooms in clinics, medical and dental offices, and outpatient facilities | 406.12(5) |
| Assembly occupancies per 518.2 (transit waiting areas, gymnasiums, skating rinks, auditoriums) | 406.12(6) |
| Dormitory units | 406.12(7) |
The 2020 edition added items (5) through (7) and removed the word "elementary" from item (4), so preschools and education facilities in general are covered, not only elementary schools. Confirm the edition your jurisdiction has adopted.
The four tamper-resistant exceptions
- More than 5 1/2 ft above the floor. A receptacle mounted above 1.7 m (66 in) is out of a small child's reach and is not required to be tamper-resistant (Exception 1).
- Part of a luminaire or appliance. A receptacle built into a fixture or appliance is exempt (Exception 2).
- Dedicated appliance space. A receptacle within the dedicated space of a cord-and-plug appliance that in normal use is not easily moved, such as behind a refrigerator or a built-in, is exempt (Exception 3, referencing 400.10(A)(6), (7), or (8)).
- Nongrounding replacement. A nongrounding receptacle installed as a replacement under 406.4(D)(2)(a) is exempt (Exception 4).
Weather-resistant and covers (406.9)
Weather-resistant is a moisture question, not an occupancy question. A location is dry, damp, or wet, and 406.9 sets the device and cover accordingly for 15/20 A, 125/250 V nonlocking receptacles.
| Location | Requirement | NEC |
|---|---|---|
| Dry (indoor) | No weather-resistant type or weatherproof enclosure required | - |
| Damp (roofed porch, canopy) | Listed weather-resistant type; enclosure weatherproof when the receptacle is covered | 406.9(A) |
| Wet (unprotected outdoors) | Listed weather-resistant type; enclosure weatherproof whether or not a plug is inserted; listed extra-duty in-use cover | 406.9(B)(1) |
A damp location is protected from the weather but subject to moisture, such as under a roofed open porch or canopy. A wet location is unprotected and subject to beating rain or runoff. The difference sets whether the cover has to keep water out with a cord plugged in, which is what the extra-duty in-use cover does.
Worked example: an outdoor dwelling receptacle
A receptacle on the exterior wall of a house, 18 in above the deck, is in a dwelling unit, so 406.12(1) requires a tamper-resistant type. It is in a wet location, so 406.9(B)(1) requires a weather-resistant type plus a listed extra-duty in-use cover. Both apply, so the correct device is a listed tamper-resistant, weather-resistant (TR-WR) receptacle in a weatherproof box with an extra-duty cover. Move the same receptacle indoors to a dry hallway and only the tamper-resistant requirement remains. Mount it more than 5 1/2 ft up inside a garage and neither applies.
Common mistakes
- Treating TR and WR as the same thing. They answer different questions. An outdoor dwelling receptacle needs both; an indoor bedroom receptacle needs only TR.
- Skipping TR on garage or accessory-building receptacles. 406.12(1) explicitly includes attached and detached garages and accessory buildings to dwelling units.
- Using a standard in-use cover in a wet location. 406.9(B)(1) requires the cover be listed and identified as extra-duty.
- Assuming the height exception applies to any high receptacle. The 5 1/2 ft exception is for tamper-resistant only; it does nothing for the weather-resistant requirement.
- Applying the rules to a locking or 30 A receptacle. Both the TR requirement and the listed WR-type requirement scope to 15/20 A, 125/250 V nonlocking receptacles.
Frequently asked questions
Where are tamper-resistant receptacles required?
In the seven areas of NEC 406.12: dwelling units (including garages and accessory buildings), hotel and motel guest rooms, child care facilities, preschools and education facilities, medical and dental offices and outpatient facilities, the 518.2 assembly occupancies, and dormitory units, for 15/20 A 125/250 V nonlocking receptacles.
Do I need a weather-resistant receptacle indoors?
Only if the indoor location is damp or wet. A normal dry indoor location does not require a weather-resistant type under 406.9, though a tamper-resistant type may still be required by 406.12.
Does an outdoor receptacle need to be both TR and WR?
At a dwelling, yes. 406.12(1) makes it tamper-resistant and 406.9(B)(1) makes it weather-resistant, so a listed TR-WR (dual-function) receptacle in a weatherproof box with an extra-duty cover is the correct device.
Is a GFCI also tamper-resistant?
Not automatically. GFCI protection (210.8) is a separate requirement from tamper-resistance (406.12). Many devices combine GFCI, TR, and WR, but you have to confirm the listing. Use the GFCI Requirement tool for where ground-fault protection is required.
Does this use the 2020 or 2023 NEC?
This tool uses the NEC 2020 text of 406.12 and 406.9. Later editions expand the areas and add nuances; always verify against the edition your jurisdiction has adopted.
Related calculators
- GFCI Breaker Sizing Calculator: where dwelling and non-dwelling receptacles need ground-fault protection per NEC 210.8.
- AFCI Requirement & Breaker Sizing Calculator: where dwelling branch circuits need arc-fault protection per NEC 210.12.
- Bathtub & Shower Zone Clearance Calculator: where a receptacle or luminaire can go near a tub or shower per NEC 406.9(C) and 410.10(D).
- Dwelling Receptacle Spacing Calculator: the 210.52 wall and countertop receptacle placement rules.
Studying for the licensing exam? Our own NEC Code Quickstart works all twelve exam calculations start to finish, each with the code reference. Also in paperback. Going for the master license? NEC Master Electrician Exam Practice has 300 master-level questions with fully worked, table-cited answers, built on the 2023 NEC.
Running an electrical contracting business? Jobber handles scheduling, invoicing, and job management. Start a 14-day free trial.
Already have the software and the follow-up still is not happening? That is an unfilled seat rather than a missing tool. Our own Role Build covers the seat: three duties built to run start to finish inside the tools you already pay for.
For deeper NEC training on receptacle device selection and code compliance, Mike Holt's NEC courses are the industry standard.
Working from the printed code? NEC code books and tab sets are available from Mike Holt.
This page contains affiliate links. ElectricalToolbox may earn a commission when you sign up or buy through them, at no additional cost to you.
Get new tools and reference cards by email
Occasional emails when a new calculator, guide, or printable card ships. No spam, unsubscribe anytime.