Stacking a 3 prong dryer atop the washer.

[Flicker Index]

How do you avoid the inadvertent bonding between neutral and ground when you do so? I watched the video

and the isolation seems to be non-existent. The little plastic sleeve isolates the hook from the dry where it grasps it, but I am not sure if the top half of the hook comes in contact with the sheet metal.

 

[LarryFine]

You really can't with existing 3-wire dryer installations. I don't consider the plastic pieces electrical isolation.

Thus, the dryer's cabinet is bonded to the neutral, and thus is in contact with the washer's cabinet and EGC.

In fact, I'd rather see the two cabinet electrically joined with a bonding strap than risk a voltage difference.

This situation can occur in almost every 3-wire major-appliance installation, which is why it's obsolete now.

 

[kwired]

Stackables didn't exist or were rare before 1996 NEC as well.

Same issues existed near ranges if there were other appliances nearby.

Actually probably a little safer if they are touching one another than if separated in case there is voltage between them.

 

[Flicker Index]

But, jumpering ground and neutral together when using a 4-prong cord is _discouraged_ stacking kit says nothing about prohibition on stacking 3-prong dryer on top of washer that is connected to a grounded receptacle.

 

[kwired]

Stackables didn't exist or were rare before 1996 NEC as well.

Same issues existed near ranges if there were other appliances nearby
Actually probably a little safer if they are touching one another than if separated in case there is voltage between them.

I should probably add to that - when both appliances are supplied directly from the service equipment.

But, jumpering ground and neutral together when using a 4-prong cord is _discouraged_ stacking kit says nothing about prohibition on stacking 3-prong dryer on top of washer that is connected to a grounded receptacle.

If both appliances are not connected directly to service equipment you have bigger chance of EGC's of anything on the feeder carrying any neutral current introduced by the dryer.