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sawdust + surface mount electrical outlets =?fire

13933 Views 9 Replies 8 Participants Last post by  HorizontalMike
Hi everyone - I'm looking for an educated response on the hazards (or lack thereof) of surface mount electrical boxes around sawdust.

I have several outlets in my show (coughgaragecough) that are regularly exposed to sawdust. They have armoured cable running into them, and there are some holes in the side of the boxes for the various mounting hardware, etc. I noticed sawdust piling up around the cable connectors and what have you, so I got the shopvac out, cleaned those puppies up, and did my best to seal them with electrical tape.

Now my question is - is this a possible hazard? Are there any covers or other safety gizmos (for lack of a better term) to better protect my shop and house? I'm worried about a spark in a box igniting some sawdust that could be sitting in there.

Any ideas or suggestions would be appreciated. Oh, and moving all the surface mounted boxes and cable into the walls isn't a possible unfortunately.


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Clean out the boxes well. You should probably remove the outlet covers and vacuum them out. You've solved a big problem in sealing up the open holes in the boxes.

You can add foam gaskets under the covers. These are sold for use with outdoor outlets.

Add "child proofing" safety plug covers (plastic inserts) to cover each of the plugs in the outlets. This will keep dust from getting into the outlets themselves.

The last thing is to put a GFCI circuit breaker of the appropriate wattage in the panel to protect each circuit. An alternative to the circuit breaker is to install a GFCI outlet in the box closest the panel (first plug in-line on each circuit.)

That should do it.

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Cleaning the boxes from once in a while will mitigate the already minimal danger. Wood is an insulator not a conductor so it's not going to cause a short, however a short will cause the sawdust to burn so it doesn't hurt to keep the boxes cleaned out and make sure the terminal screws are tight.

As an electrician the most common cause to faults in receptacles I find are loose connections, loose connections generate a lot of heat and sometimes arcs which is obviously not good in a sawdust filled outlet box. Make sure that the wires are terminated under the screws and not in the "punch ins" on the back of the receptacle. The punch ins will loosen over time.

I vacuum mine out about once a year, and even then the amount of sawdust I find is minimal

Unless you have receptacles near water or use a lot of extension cords GFCI's are not really needed.
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What about replacing the boxes with sealed water proof boxes and outside covers?
I recently moved and dismantled my workshop and found the exposed outlet boxes did have some sawdust in them after six years. I do all of my own wiring and none of my connections were loose. I do not ever use the push in connections I always use the screw connections and make sure they are wrapped all around the screw and tight as suggested by Scot.
The danger of dust inside the boxes is really minimal. The only time this can be an issue is if you have arcing inside the box. As long as the connections inside the box are tight, the dust is simply a nuisance. If the proper gauge wire is used, there is no advantage to either connection type on the device (push in vs. screw).
Thanks everyone. I did some of the electrical myself with my buddy who's an electrician. I didn't really think about the sawdust issue until I noticed it in practice. When we did the wiring, we used the screws - the punch in connectors are just silly. We also wrapped around all the plugs with electrical tape, covering up the terminals, so there shouldn't be no arcing and they shouldn't come loose.

I guess the question was more of a theoretical one than a practical one. The idea about the outdoor box covers is valid, but I don't think there are any connectors for armoured cable into those boxes (assuming we're talking about the same ones) and it's usually the outlet that I'm working by and have something plugged into that gets sprayed with sawdust, so the cover would be open anyways.

Thanks for your input everyone! Much appreciated… There has been a bunch of house fires here in Calgary in the last while so it got me thinking.
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I would venture a guess that using compressed air to "blow" out the dust might be a bit safer than using a powered vacuum. This way you can avoid touching the box connections and you wouldn't have to kill the power to the shop and probably wouldn't even need to remove the covers. A quick check of the one you 'think' might be the worst for dust, might confirm or dismiss this as an option. Just an idea…

And yes, I too was an electrician earlier in life, or as some might say "...once upon a time…" ;-)
I would think the chance of getting moiture out of your compressed air could cause more safety issues than using a shop vac. Canned air is supposed to be moisture free. I think if dust in a recepticle catches on fire, you have more issues than sawdust.
Geez Grampa, are you not you reaching a bit? I do not know about YOU, but I drain my compressor tank of h20 daily… Don't YOU?

AS a matter of fact, I drained the H2O less than two hours ago… Have you?
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