Thread: Did not expect that in there!!

so having cleaned out the saw dust, does the motor now work?

I've seen that happen quite a few times especially on motors inside ww machinery cabinets with inadequate dust extraction .
My examination of these junction boxes indicates it happens in a couple of ways.

The connections between the junction box and the motor are not sealed so either the fan pushing air through the motor or the motor itself just by turning creates a slight vacuum inside the box and sucks air ladened with fine sawdust into the box though any gaps in the box. In your case, the complete lack of a cable gland is clearly a problem.

Even using a cable gland and the connections between the box and motor gland sealed I have still seen fine dust inside motor junction boxes.
The junction box is attached to the motor so when the motor runs for a while the box and air inside it heats up and expels some air.
As the motor and junction box cools it sucks air back into the box along with any fine dust hanging around in the air, which it does for many hours after the last dust making activity,
A good quality seal between the main box housing and it's lid will help with this. If your motor boxes are not sealed a thin smear of silicone is usually sufficient to do the job.

Both also point to inadequate dust extraction. I have also seen it happen on motors outside cabinets. One was an old lathe motor and one was on a home made disc sander.

Many years ago a powerpoint in my shed under a window, unbeknownst to me partially fill up with sawdust as it was in the direct firing line of wood dust coming off a saw. During a storm, rain came in under the window and dribbled into the powerpoint wetting the sawdust and causing a short, setting it smoking and eventually tripping the house RDC. Luckily I was at home up in the house and noticed the power was off. After checking everything inside ether house I went down to the shed and as I opened the door the powerpoint was furiously smoking.

Originally Posted by RedShirtGuy

When I opened up the terminal box to disconnect the power cable I was met with a rather compact mountain of saw dust.

Same problem I had and it's been a great wake up call. Now waiting for the report from the motor winder.

mick

One Friday late in the afternoon there was a slight smell of smoke in the workshop, checked every where and the smell was definitely inside the shop, no smoke just a distinct smell.

After searching for several hours and finding nothing gave up and went home.

On Monday one of the machines was not running properly, this was traced to a faulty cable coming from the switchboard. Opened the switchboard and found a thick layer of charred sawdust covering all of the boards interior. A faulty connection had ignited the dust and it had smouldered for who knows how long. Luckily the switchboard was lined with asbestos and the fire had not spread nor had it burnt any of the wires.