Induction? Grounding?

[AudioHTIT]

Those who have followed my Credenza project may have seen that the cabinet sits on a metal base that supports the cabinet and the equipment (currently closing in on 900 lbs). It also allows the structure to roll in and out from the wall. The base is welded 1x4 & 2x4 rectangular steel.

La Credenza also has a power distribution system, 12/3 insulated cable feeds outlets in each equipment ‘cubby’, the four legs feed back to a junction box where a single cable runs out and plugs into a 20A circuit. I finished all that this last weekend, and after inspecting and checking my work for continuity, I plugged it in. No sparks, everything tested and worked fine.

However, while I was checking voltage, for some reason I tested from the metal caster base to ground and found 17.5 volts. Again all the wires are well insulated and nothing is touching the base, nor is the base grounded. I tested several times and came to the conclusion that I must have created some kind of transformer when the power cable crossed the channel steel and induction is creating a voltage in the base. I tried grounding the base and again no sparks, everything fine. If I ground the base the voltage goes away as expected.

I put a Kill-o-watt meter on the plug and found no power or current being drawn with or without the ground, so the voltage ‘potential’ didn’t translate to any measurable current flow.

So, here’s the question... should I ground the base? Or let the potential run wild? And why?

Thanks for your thoughts
-Bruce

Here’s the base after mounting the wheels.

[26gary26]

First of all congrats on your project it looks awesome. I assume that all of your equipment if going to be on this. I am not an electrician but once you get your equipment all set up and turned on if you notice any interference I would be concerned of course. Steel is one hell of a conductor. I remember a construction project I was on where steel studs were used instead of wood studs. It provided many issues such as interference. I think your going to be fine. Good luck with your final install. I am sure someone with electrical knowledge will chime in.

[Ex_Vintage]

I would definitely ground it. When all equipment is loaded, the power distribution to your equipment will capacitively couple stray voltage into the "floating" steel structure. This is not a safety issue, since the voltage is not supported by any significant current flow. The main reason to ground the structure is to provide an electrostatic discharge for ESD purposes. This will better protect you and your equipment and will provide a grounded reference for any signal level interconnect wires, lessening the possibility of induced noise.

[AudioHTIT]

Jul 13, 2018 22:26:53 GMT -5 Ex_Vintage said:

I would definitely ground it. When all equipment is loaded, the power distribution to your equipment will capacitively couple stray voltage into the "floating" steel structure. This is not a safety issue, since the voltage is not supported by any significant current flow. The main reason to ground the structure is to provide an electrostatic discharge for ESD purposes. This will better protect you and your equipment and will provide a grounded reference for any signal level interconnect wires, lessening the possibility of induced noise.

Thanks for the reply, I had to flip the unit over a couple days ago and made the decision to ground (once it’s upright I can’t get to the wiring anymore). Glad there’s some reasoning to ground it other than, ‘it seemed like the right thing to do’.

[novisnick]

Jul 14, 2018 1:04:51 GMT -5 AudioHTIT said:

Jul 13, 2018 22:26:53 GMT -5 Ex_Vintage said:

I would definitely ground it. When all equipment is loaded, the power distribution to your equipment will capacitively couple stray voltage into the "floating" steel structure. This is not a safety issue, since the voltage is not supported by any significant current flow. The main reason to ground the structure is to provide an electrostatic discharge for ESD purposes. This will better protect you and your equipment and will provide a grounded reference for any signal level interconnect wires, lessening the possibility of induced noise.

Thanks for the reply, I had to flip the unit over a couple days ago and made the decision to ground (once it’s upright I can’t get to the wiring anymore). Glad there’s some reasoning to ground it other than, ‘it seemed like the right thing to do’.

Its so beautiful and electrifying! It had better be grounded! 👍🎶🎶🎶🎶🎶🎶

[Priapulus]

Ground it.

The steel will act as an antenna for any stray signals in the air, and a conductor for any short that may hit it. You want to channel that noise or shorts to ground. In a radio room or lab, every metal fixture, table and piece of equipment will be bonded to ground/earth.

Very nice design; I'm going to poach it...

Sincerely
/b