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Old 09-15-2019, 02:11 PM   #21
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Quote:
Originally Posted by tates1882 View Post
46.2 Location
46.2.1 All operating coils of electro-mechanical devices and indicator lamps, including the transformer primary winding of an indicator lamp, shall be directly connected to the grounded side of the control circuit.
Exception: A switching device that is provided within the industrial control panel as specified in the exceptions to 45.3.1 is able to be located between the coil and the grounded side of the control circuit.


45.3.1 All control circuit contacts shall be arranged to open the ungrounded conductor to the coil.
Exception No. 1: Electrical interlock contacts on multi-speed motor controllers are not required to comply when the wiring to these contacts does not extend beyond the control enclosure.
Exception No. 2: Overload relay contacts are not required to comply when the wiring to these contacts does not extend beyond the control enclosure.
Exception No. 3: Contacts of multi-pole control circuit switching devices that simultaneously open both sides of the control circuit are not required to comply.
Exception No. 4: Ground test switching device contacts in ungrounded control circuits are not required to comply.
Exception No. 5: Solenoid test switching device contacts in ungrounded circuits are not required to comply.
Exception No. 6: Coils or contacts used in electronic control circuits are not required to comply.
Exception No. 7: ′′Run′′ pushbuttons for two hand operating are not required to comply when overcurrent protection is provided in each conductor.

Its pretty specific when you can do switching in the grounded circuit.
So, as long as you don't leave the control enclosure, pretty much whenever.
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Old 09-15-2019, 02:29 PM   #22
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Originally Posted by CoolWill View Post

So, as long as you don't leave the control enclosure, pretty much whenever.
pretty much there may be a few more requirements a little deeper in the standard that has to do with specific use control panels, this is for a basic industrial control panel.

I break all my grounded conductors across ol contacts for almost all mags/contactors.
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Old 09-15-2019, 02:31 PM   #23
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This is why you see a white conductors in front of the msp’s.
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Valid case for switching neutral?-ae5f4e32-b8c8-4e8b-b2ce-82fb95c18000_1568572226561.jpg  

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Old 09-16-2019, 06:39 AM   #24
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This is why you see a white conductors in front of the msp’s.
Looks nice! Can we see the rest of that panel?

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Old 09-16-2019, 07:14 AM   #25
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Quote:
Originally Posted by tates1882 View Post
46.2 Location
46.2.1 ...

45.3.1 ...
Its pretty specific when you can do switching in the grounded circuit.
Quote:
Originally Posted by CoolWill View Post
So, as long as you don't leave the control enclosure, pretty much whenever.
Quote:
Originally Posted by tates1882 View Post
pretty much there may be a few more requirements a little deeper in the standard that has to do with specific use control panels, this is for a basic industrial control panel.

I break all my grounded conductors across ol contacts for almost all mags/contactors.
Correct me if I am wrong, this is my understanding.

For @tates1882 is complying with the UL 508A standard - he took the UL test, has the UL T-shirt, gets the UL inspection, so he's a legit UL panel builder. He makes a listed piece of equipment, the guts of which are outside the scope of the NEC.

If you're not a panel shop, you are installing to NEC, building a control panel to article 409, different rules apply. As @sparkiez points out, it's simple; article 404.2 applies to all switches.

Now if you're just building something for your workbench, I can not imagine you're subject to either, a man's contraption is his castle.
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Old 09-16-2019, 09:04 AM   #26
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Correct me if I am wrong, this is my understanding.

For @tates1882 is complying with the UL 508A standard - he took the UL test, has the UL T-shirt, gets the UL inspection, so he's a legit UL panel builder. He makes a listed piece of equipment, the guts of which are outside the scope of the NEC.

If you're not a panel shop, you are installing to NEC, building a control panel to article 409, different rules apply. As @sparkiez points out, it's simple; article 404.2 applies to all switches.

Now if you're just building something for your workbench, I can not imagine you're subject to either, a man's contraption is his castle.
Well I think it would depend on your states rules regarding un-listed equipment, Idaho for example will allow for a qualified field evaluation body to certify equipment. The FEB doesn't have to be a NTRL to satisfy the state but does need to be to satisfy OSHA. I build listed, un-listed, and NEC based ICP's, some customers( I'm a multi-state, 2 country supplier) don't want the listed sticker or want components that UL won't allow so chose to use a FEB or AHJ. We require indemnification if they don't buy the listed version, as this removes a layer of protection for my shop. I normally won't build a panel under the NEC with more than 3 motors and simple controls as most AHJ's struggle to properly inspect and evaluate said panel.

What I'm getting at is if I was the OP, I would switch the grounded conductor, follow ul508a, and hire an FEB to certify the build.
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Old 09-16-2019, 04:57 PM   #27
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You are allowed to switch neutral as long as you are breaking the connection to any associated ungrounded wire simultaneously . ...

That. ^

Also, the ONLY reasons that the "neutral" was/is used in motor OL circuits is tradition, based on 1) an older practice that is no longer done (very much) and 2) the fact that originally, motor OLs were separate per pole, not one single 3 pole relay.

1) The older practice is from the fact that it USED TO BE very widespread practice to use the Line voltage as the control voltage (called "common control"). So if you had 480V power for a motor, you used 480V coils on the starters. In that case, the "other side" of the contactor coil was NOT actually a neutral circuit, it was just as hot as the other side.

2) Older starter assemblies used separate 1 pole OL relays, so the trip contacts were wired in series and up until 1978(?), three phase motors only required 2 OL relays.

So JIC and NEMA, in order to facilitate the simplest factory wiring that covered both of the above issues, put the OL relay contact(s) on the RIGHT side of the coil in a ladder diagram. It is ONLY when we use 120V coil that this BECOMES the "neutral" side of the circuit, but that was never the INTENT.

Note that none of the above wires are white...

Since then, so much time has passed now that the vast majority of people in the industry have never even seen common control used, nor have they seen separate 1 pole OL relays wired in series. So they have created many different myths as to why the OL relay contact is on the "neutral" side. All of them wrong.

Side note: If SAFETY is your concern, you should not be using a solid state contactor as an isolation device. It does NOT isolate.
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Last edited by JRaef; 09-16-2019 at 05:00 PM.
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