Uploaded December 2025 | Updated September 2026, 2 weeks ago
How many of you knew this Dimmer Rule in building codes: If you use dimmers (like 3-way dimmers), each switch must be capable of turning the light to 100% brightness from its location, ensuring full illumination is always accessible. (Automatic dimmers are allowed, if they sense the presence of people in the hallway or stairway and automatically illuminate it adequately upon detection of occupants.) 💡
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2017 National Electrical Code - 210.70(A)(2)(3)(4) Lighting Outlets in Additional Locations
"Lighting outlets controlled in accordance with 210.70(A)(2)(3) shall not be controlled by use of dimmer switches unless they provide the full range of dimming control at each location."
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GSA Residential Code 2024 - 39 Power and Lighting Distribution, E3903.3 Lighting Outlets in Additional Locations
"Dimmer control of lighting outlets installed in accordance with this section shall not be permitted unless the listed control devices can provide dimming control to maximum brightness at each control location for the interior stairway illumination. Exception: In hallways, stairways, and at outdoor egress doors, remote, central, or automatic control of lighting shall be permitted." The GSA code also explicitly references NEC 210.70(A)(2)(3)(4)
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TL,DR: the use of dimmer switches at interior stairways is permitted only when the lights can be adjusted to full brightness at each switch location. The idea is to avoid a situation where a dimmer is adjusted to the lowest illumination level at one end of the stairway or hallway and then it cannot be adjusted by someone at the other end of said stairway or hallway. So now you know... enjoy! 👍😁👍
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I post dumb questions to Reddit and sometimes answer folks' questions there, too...
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This is my GitHub. I post my design files there...
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I don't use Twitter anymore and neither should you...
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This is my personal web site. Most things i create wind up online...
deviating.net
This is my company. We're good at stuff...
enterthecore.net
This is where I train. Come and learn badass skills...
redteamalliance.com
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How many of you knew this Dimmer Rule in building codes: If you use dimmers (like 3-way dimmers), each switch must be capable of turning the light to 100% brightness from its location, ensuring full illumination is always accessible. (Automatic dimmers are allowed, if they sense the presence of people in the hallway or stairway and automatically illuminate it adequately upon detection of occupants.) 💡
- -- ----- ----------
2017 National Electrical Code - 210.70(A)(2)(3)(4) Lighting Outlets in Additional Locations
"Lighting outlets controlled in accordance with 210.70(A)(2)(3) shall not be controlled by use of dimmer switches unless they provide the full range of dimming control at each location."
- -- ----- ----------
GSA Residential Code 2024 - 39 Power and Lighting Distribution, E3903.3 Lighting Outlets in Additional Locations
"Dimmer control of lighting outlets installed in accordance with this section shall not be permitted unless the listed control devices can provide dimming control to maximum brightness at each control location for the interior stairway illumination. Exception: In hallways, stairways, and at outdoor egress doors, remote, central, or automatic control of lighting shall be permitted." The GSA code also explicitly references NEC 210.70(A)(2)(3)(4)
- -- ----- ----------
TL,DR: the use of dimmer switches at interior stairways is permitted only when the lights can be adjusted to full brightness at each switch location. The idea is to avoid a situation where a dimmer is adjusted to the lowest illumination level at one end of the stairway or hallway and then it cannot be adjusted by someone at the other end of said stairway or hallway. So now you know... enjoy! 👍😁👍
- -- ----- ----------
Sign up for give-away drawings here...
deviating.net/contests/give-aways
I'm on the Fediverse. That's a great place to find me...
https://defcon.social/@deviantollam
I'm also on Instagram. I mostly use it for liking my friends' photos...
instagram.com/deviantollam
Bluesky has picked up a lot of momentum, and I'm over there, too...
https://bsky.app/profile/deviantollam.bsky.social
I'm also on Discord, but mostly only because my daughter uses it...
discord.com/users/deviantollam
I post dumb questions to Reddit and sometimes answer folks' questions there, too...
reddit.com/u/deviantollam
This is my GitHub. I post my design files there...
github.com/deviantollam
I don't use Twitter anymore and neither should you...
twitter.com/deviantollam
This is my personal web site. Most things i create wind up online...
deviating.net
This is my company. We're good at stuff...
enterthecore.net
This is where I train. Come and learn badass skills...
redteamalliance.com
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