2 Grounding path

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dewit45065

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I have a control cabinet that has two sources of power, UPS and Regular power. Both sources power a different power supply. The problem I have is that the power supplies are carring the ground to the back plate, which ties the two ground paths together. Do these Grounds have to be isolated? The ups power is used for computer equipment.
 
dewit45065 said:
I have a control cabinet that has two sources of power, UPS and Regular power. Both sources power a different power supply. The problem I have is that the power supplies are carring the ground to the back plate, which ties the two ground paths together. Do these Grounds have to be isolated? The ups power is used for computer equipment.
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No. I had to read your post several times.

The NEC IMO coudnt care less about computers
 
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dewit45065 said:
I have a control cabinet that has two sources of power, UPS and Regular power. Both sources power a different power supply. The problem I have is that the power supplies are carring the ground to the back plate, which ties the two ground paths together. Do these Grounds have to be isolated? The ups power is used for computer equipment.
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If done to code, the grounds are going to be tied together at some point anyway before they come to the cabinet. There is no generally no good reason not to tie them together in the cabinet.

There is never a NEC requirement to use isolated grounds. It is a design decision. And an isolated ground is sort of a misnomer anyway. It only means that the only physical connection is at the service point and is not directly connecting to any other metallic parts along the way.

If you Ohm out an "isolated" ground to an regular ground wire, you should find they have a very low resistance between them.

IMO, the use of IG serves no real purpose in the vast majority of cases. People that really know what they are doing might get some benefit from them in specific cases, but the average guy is just not going to benefit from using them.

<added>Is there any provision in the NEC for an IG other than to a receptacle?
 
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