Dangerous situation? Accidentally ran a vacuum cleaner on a dimmer switch...

[gamp945]

Hi all,

I've done quite a bit of electrical work by myself now and am pretty careful about doing things right. But I just had - maybe? - a close call with a very overheated dimmer switch. I'll explain what happened below.

This weekend I did an electrical makeover to the living room. I added two dimmer switches. One dimmer switch operates new ceiling pendants. The other dimmer switch operates two wall receptacles for floor lights. Notably, I had to do some rewiring to get the dimmer switch to operate the wall receptacles. In fact, I am not quite done yet and this dimmer switch operates *all* of the wall receptacles in the living room. Tonight I had planned on running a new NM cable to some of the wall receptacles so that they would be powered by a separate, non-switched circuit.

Before I could finish the job, my wife started vacuuming in the living room tonight and plugged the vacuum into one of the switched outlets. When the vacuum did not work, she turned on the dimmer switch and the vacuum then turned on. The dimmer switch was set to the highest position and the vacuum seemed to run normally. When she was finished, she went to turn the switch off and from a different room a heard a yelp, OWW! The light switch (as well as the adjacent switches and switch plate) had become extremely hot. I immediately shut off the breaker until I could understand what had happened.

So what happened? I think that the modern "universal" dimmer switch is rated for only 700W (incandescent) or 450W (CFL/LED); when the switch is first turned on after being installed, I believe it automatically detects the load type (incandescent or CFL/LED) and varies the voltage accordingly. So when my wife turned on the 1300W vacuum cleaner, the dimmer switch was quickly overloaded and became hot as Hades.

Amazingly, the switch itself appears undamaged. But I am strongly considering throwing it in the garbage just in case something was damaged.

This brings me to question the safety of installing dimmer switches for receptacles. In my experience, they are quite common. But are they code compliant?

 

[Norcal]

It’s not permitted to put a dimmer on wall receptacles, the situation you encountered is one reason why. Put dimmers on the cords of the floor lamps.

 

[TRWham]

It's in 404.14(E).

 

[cybrdyke]

In your experience they're quite common?? Where are you located?
This is a big fat NO !!
CD

 

[sparky 1971]

Yeah, that's a no go because of the fact something other than a lamp could get plugged in. That being said, I did it in my own house. I used a single receptacle and labeled the plate just for a lamp in the bedroom. That didn't stop my wife from unplugging the lamp so she could use it for the vacuum. It took the dimmer out and gave me a chance to explain to her what I mean when I say that just because something is fool proofed, that doesn't mean it's idiot proofed.

 

[gamp945]

In your experience they're quite common?? Where are you located?
This is a big fat NO !!
CD

I have lived in more than 30 homes in both Canada and the USA and recall using floor lamps on dimmer switches many, many times. That's not to say that this was correct, just that in my experience it is common. Even more common is receptacles on a toggle switch. Maybe toggle switches (code compliant I think?) get switched out with dimmers sometimes?

My current home was built in the 1960s and had several receptacles on old dimmers. I updated the dimmer switches to modern versions and haven't had a problem because the receptacles (for lamps) were behind furniture and my wife couldn't accidentally plug a vacuum into them. After today's experience though, I think I will be removing those dimmers.

 

[gamp945]

It's in 404.14(E).

Thanks for the code reference. A bit more searching and I found that apparently there was an addition to the 2014 NEC that allowed dimmer-controlled receptacles with specially-designed receptacle/plug combinations. It looks like the only manufacturer was Lutron. Here is a photo:

406.15 Dimmer-Controlled Receptacles.

The bottom receptacle in the duplex requires a special plug cap that mates with the receptacle that will be controlled by the dimmer.

www.electricallicenserenewal.com

However, that code addition was removed in 2017 and the special receptacles are no longer code compliant, although they are still available for purchase (old stock maybe).

It is interesting how the code addition lasted only one cycle (2014 to 2017). I'm halfway tempted to get a couple of the special receptacles and matching plugs even though technically they are no longer code compliant - they would in fact allow me to have floor lamps on dimmer switches without the risk of accidentally plugging in a vacuum or similar.

 

[yatg]

Not advocating this, but you could use 6-15 receptacles and replace the lamp plugs with 6-15Ps.

 

[cybrdyke]

Thanks for the code reference. A bit more searching and I found that apparently there was an addition to the 2014 NEC that allowed dimmer-controlled receptacles with specially-designed receptacle/plug combinations. It looks like the only manufacturer was Lutron. Here is a photo:

406.15 Dimmer-Controlled Receptacles.

The bottom receptacle in the duplex requires a special plug cap that mates with the receptacle that will be controlled by the dimmer.

www.electricallicenserenewal.com

However, that code addition was removed in 2017 and the special receptacles are no longer code compliant, although they are still available for purchase (old stock maybe).

It is interesting how the code addition lasted only one cycle (2014 to 2017). I'm halfway tempted to get a couple of the special receptacles and matching plugs even though technically they are no longer code compliant - they would in fact allow me to have floor lamps on dimmer switches without the risk of accidentally plugging in a vacuum or similar.

You can use a smart bulb with a companion dimmer switch. No electrical issues there. Might even have an app. For instance, I have Philips hue bulbs. I can dim them with a wall dimmer, an app, or by telling Alexa to dim them. I can even make them any color I want.

 

[engineer2]

I have one for halogen puck lights under a built-in bookshelf. I know it is against code, but it is in a location where it is unlikely to be abused. I painted the receptacle gray. I'll remove it before we move since it is obsolete anyway. Nowadays many LED puck lights come with a little remote to dim the lights.

For a floor lamp you could get one of those smart light bulbs that can be remotely controlled.

 

[rburke65]

I’m getting old, but I’ve never seen or installed a dimmer on a receptacle.

 

[TTTTTT]

I’m getting old, but I’ve never seen or installed a dimmer on a receptacle.

Dimmer on a receptacle..NO. But definitely controlling an outlet from a switch was very common. Allowed builders to avoid putting overhead ceiling lights in , but could still turn a light on as you entered a room via a plugged in lamp. Popular in the 80s. May be removed from most codes now.

 

[PelicanPines]

I've owned a dozen homes or so... an apartment building my family owned and maintained. I know not to put a dimmer on an outlet simply because it's WRONG. The dimmer switches are meant for low wattage lights... not a TV or Vacuum or LAPTOP or anything else you would plug in ... inside a living room, bedroom, kitchen.

There is a reason it is illegal (based on code)... it's dangerous.

 

[MAD]

It is not just an issue of the wattage; this type of dimmer chops up the wave form of the current in order to dim the light. This is often true even when the dimmer is set at full intensity. Many devices can't run properly without nice clean power. I have seen numerous times where people have "let the smoke out" of non-lighting loads plugged into theatrical dimmers which had plenty of capacity in terms of wattage. (Receptacles wired to dimmers are commonplace in Theaters)

I see nothing wrong with dimming a lamp receptacle if you use a different connector like an L5-15 twist-lock. But If it is a single gang box, it may not be possible to fit a non-dimmed outlet in the same location.

 

[TRWham]

... Popular in the 80s. May be removed from most codes now.

Yeah, it was very common in the 70s and 80s and it's still permitted by the NEC (210.70(A)(1) Exception 1). I don't see it done as much anymore, but most of the projects I see are custom and we are installed recessed lights for general lighting for most clients.