Single phase vs 3 phase systems

[drcampbell]

If you understand trigonometry and vector math, and apply it to three-phase and single-phase systems, it will be pretty obvious.

If you don't learn trigonometry and vector math, there is probably no approximate analogy that will make any sense. (with the possible exception of delta and wye diagrams carefully drawn to scale)

 

[jaggedben]

Thats a new one for me. Where is purple required?

San Francisco. Goes back to when they had their own city code.

 

[kwired]

NEC itself doesn't require any particular color scheme for any voltage system. It does require identifying system and phase when there is more than one voltage system on the premises. There is widely used color schemes out there but are not a requirement unless you have local jurisdiction amendments that reference them.

If you only have one voltage system there is no requirement to identify phases other than high leg when you have such a system and the grounded conductor is also present at that location in the system.

 

[augie47]

Thats a new one for me. Where is purple required?

One place is Chattanooga. I can't recall if 'required' but Orange is only allowed for high-leg so purple won by default.

 

[drcampbell]

That's a new one for me. Where is purple required?

Pretty sure it was never required, but I visited one house in Chicagoland which was wired with the required metal conduit, and everything¹ (?) inside was orange or purple.

¹ can't say for sure; didn't open every box, but I didn't see any other colors.

 

[Seven-Delta-FortyOne]

NEC itself doesn't require any particular color scheme for any voltage system. It does require identifying system and phase when there is more than one voltage system on the premises. There is widely used color schemes out there but are not a requirement unless you have local jurisdiction amendments that reference them.

If you only have one voltage system there is no requirement to identify phases other than high leg when you have such a system and the grounded conductor is also present at that location in the system.

As of 2020, which we’re on in California, orange is still required. “Or other effective means”, which I guess means you could hang a tag that says “High Leg”?

 

[Seven-Delta-FortyOne]

San Francisco. Goes back to when they had their own city code.

Ot was require for high leg, or something else?

 

[jaggedben]

Ot was require for high leg, or something else?

Purple is required for the high leg.
Although I've seen orange in the city, too.

Chapter 1. General

Legal publisher offering ordinance codification services for local governments, specializing in providing codes of ordinances in print and on the Internet

codelibrary.amlegal.com

Actually if you keep reading you'll see they also mandate red and black for 120/240 and red black blue for 208/120.

 

[Birken Vogt]

It bothers me when people say purple, I was taught violet by forceful shouting and never forgot it.

 

[kwired]

As of 2020, which we’re on in California, orange is still required. “Or other effective means”, which I guess means you could hang a tag that says “High Leg”?

Yes NEC knows best how to be specific and yet still leave the same subject as gray matter