Author Topic: Question: 240v 3phase Ground?  (Read 12130 times)


Re: Question: 240v 3phase Ground?
« Reply #30 on: January 24, 2019, 06:17:31 AM »
Heres a great explanation...

Very very interesting... very interesting!!
Thanks for posting that.


Re: Question: 240v 3phase Ground?
« Reply #31 on: January 24, 2019, 09:03:24 AM »
Yeah, Mike Holt will make your head spin trying to understand grounding and bonding. 
I our world, keep it simple and have one point of bonding to the ground rod.  That should be at the meter box where the power comes in to the shop and or house.  You need the one ground rod/bonding point.
Electrical inspectors out there, and not all, think that every machine, piece of equipment, etc needs a ground rod installed.  Don't do it!  Even if you have two separate buildings feeding off the same electric service, don't add a second ground rod for that building. This can be argued on too.  The City of Houston requires a ground rod installed at each machine installation regardless.  I've seen electricians go in and disconnect that ground after the inspector leaves, too.  And I've seen CNC machines go down for no reason and there was a electrical storm three miles away. 
Grounding remains a mystery to me.  I just follow the experts and not look back.


Question: 240v 3phase Ground?
« Reply #32 on: January 24, 2019, 11:27:36 AM »
Lol He is definitely an excitable dude.   I work in the industrial electric heating element, sensor and controls business and subscribe to several  publications such as this one that have tons of good articles and information on the subject.
« Last Edit: January 24, 2019, 11:29:39 AM by PJB »
1991 Bridgeport Series I 2J-VS  9"x48"
1979 Clausing Colchester Bantam Mk2 11"x30"
1972 Harig Super 612
2015 Tormach PCNC-1100 Mill

"They wants what you gots!"


Re: Question: 240v 3phase Ground?
« Reply #33 on: January 26, 2019, 10:17:16 PM »

Also, trying to understand phase taping. Can I run a hot leg with white in a single voltage 3phase only raceway (black, red, white) or do I need blue. NEC seems to suggest that I can use other colors as long as there is no neutral and no other voltages.

Huge thanks!!


Here's a perfect picture at 13:26 on phase taping.

They are different between low and high voltages.



Re: Question: 240v 3phase Ground?
« Reply #34 on: February 07, 2019, 07:08:02 AM »
Thanks for the input!!
I've watched all of the possibly relevant Mike Holt videos while here in the metro where all I can do is load the truck with stuff...
I especially appreciate that he explains "why".

I spoke with my local inspector and am hoping to take finish install early next week and call for inspection on Thursday.
I will take pics on the completed electrical work and of the incomplete shop space.
Hopefully he won't need to come for a second inspection because of changes I may need to make.