Hum in Speakers with New Dedicated 20 amp Circuit

@erik_squires

I am not sure how far back the NEC allowed metal conduit to be used as an equipment grounding conductor. The earliest NEC I have is 1971.

1971 NEC 250.91 (B). Types of equipment grounding conductors.

(1) Copper conductor or other corrosion-resistant conductor ... more wording solid, stranded ect... Nothing said specifically about the use of Aluminum conductor.

(2) Rigid Metal Conduit

(3) Electrical Metallic Tubing (EMT)

(4) Flexible metal conduit approved for the purpose, .......

(5) Armor of Type AC metal-clad cable

(6) The sheath of Type MI cable

(7) The sheath of Type ALS cable

(8) other ......

/ / / /

From earlier post:

Yes you can. NEC 250.118 (2) (3) (4)

This was not a complete list of all the types of equipment grounding conductors allowed. I just stopped at #5.....

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guamie

12 posts

02-27-2023 at 10:02am

Separate the grounds and the neutral. Ground to the left side bar and the neutral to the right side bar. I’m an electrician and get called a lot for these corrections.

@guamie

What are you going to about the feeder bare aluminum neutral conductor? ...... (The Grounded Conductor).

I can see where it is touching the metal panel enclosure in several places. It is also in contact with the feeder metal conduit from the main service panel. An electrical hazard? No... Still not right though... Not if it is a sub panel anyway. We are assuming it is though...

The OP is not qualified to do anything in the panel. And apparently the OP has left the building because he hasn’t responded to questions...

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@jea48 I believe you.  I was probably confounding the local code requirements with the NEC.  My mistake.

Edit to my above post. 🔼 🔼 🔼

Looking at the photo again this morning of the feeder conduit entering on the left side of the panel it may very well be PVC conduit. Not metal conduit. If that is the case the OP should not move the EGC ground wires to the ground bar on the left side of the panel.

I based the possibility the feeder conduit may be PVC by looking at what can be seen of the connector’s color of the threads and the poor image of the connector on the outside of the panel enclosure. I also based my possible conclusion on the 50A branch circuit load conduit exiting the top right side of the panel is PVC. 100% sure the feeder conduit is PVC? NO... Without knowing for sure it would be bad advice, imo, to move the EGC ground wires to the ground bar on the left side of the panel.

IF the feeder conduit is PVC the ground fault current path is to the feeder neutral bar/conductor. Moving the EGC ground wires to the ground bar on the left side of the panel, the ground fault current path would be through the panel metal enclosure to parts of the touching places where the bare aluminum feeder neutral conductors is in poor contact with the panel enclosure. A very poor low impedance connection to say the least...

Looking at the photo again this morning of the feeder conduit entering on the left side of the panel it may very well be PVC conduit.

I concur looking at the color, saturation and reflectivity of the visible threads. It's a very close match to the PVC exit.