Grounding a piece of equipment

Thread Starter

gerstley

Joined Nov 20, 2015
58
I am building a machine that uses a 12 volt DC motor. I was looking to use a class II (double insulated) power supply to go from 120 v AC to 12 v DC. The power supply would be located inside the electronic circuit enclosure. The power supply doesn't have a ground terminal on the AC side. Since the power supply is inside the enclosure, do I need to use a 3 wire power cord and connect the ground wire to the metal enclosure? I would think it would be possible to have a wire come loose inside the enclosure and potentially shock someone without a ground connection.
 

profbuxton

Joined Feb 21, 2014
419
Don't know the regs. where you are Max, but here in OZ if a piece of equipment is double insulated (and marked as such) an earth connection is not required and such equipment is marked do not earth. I.E. double insulated 240V drill has no earth, even if the chuck is metal.
In the posters case, not knowing the 120VAC connection terminal type(open screw or flex cable internally terminated in the supply), if it is open screw type there may be a remote possibility of the AC wire coming adrift, so I agree the enclosure(if metal) should be earthed.
 

Thread Starter

gerstley

Joined Nov 20, 2015
58
The power supply is encapsulated with screw terminals. I guess I will just run a ground to the metal enclosure.
 

MaxHeadRoom

Joined Jul 18, 2013
20,911
So does that mean that the earth ground is not required?
If it actually qualifies as 'Double Insulated' then normally a ground is not needed.
This normally applies to portable equipment however.
If it has a metallic enclosure to house various circuits, then an Earth ground is required.
Max.
 
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