Where's the Violation?

[david]

Existing (old, small) building. Only one panel: 175 amp, 120/208V, 3 phase, circa 1976. Served by outdoor pad-mounted, 112.5 KVA transformer. There is no conductor connected to X3. Hand-written label on panel says 120/208V-1 ph. There are 1-pole breakers in all 42 positions. Panel schedule shows most of them in use, including all three phases.

My best guess is that there is a jumper conductor between two of the phases, so that power can be fed to any breaker on any leg. I don’t know service conductor sizes, so I can’t say whether one leg is carrying too much current. My project will be adding load for HVAC equipment.

I want to tell the owner that the panel has to be replaced. I want to include code citations to forestall any gripes about cost. Other than 110.3B, what can I cite?

It could have been a high leg delta, but the current occupants only have 120 V loads, so they somehow (hopefully legally) put a jumper between two of the bus bars. That way they avoid the high leg and get a third more slots to use.

That's not possible because there is no wild leg in this panel.
How do we know this?
Because we already know there's only 2 phases coming into the existing 3 phase panel from the transformer.
How do we know one of them is not the wild leg?
Because the panel is full of 1p 20's and they would have already burned up half or more of anything coming off of this panel because it's full of 1p 20's.

Plus,

If you put a jumper between 2 bussbars where 240v delta actually did exist, the panel would have had a nice smokey smell and most of the parts would have been blown out of it from a direct phase to phase fault.

Jap>

I do not think his concern was at the panel. Although the panel is hand written labeled 120/208 single phase, his concern most likely was in pulling the third phase and the source actually being 120/240 3 PH

Though it was clearly stated X3 is the missing Phase and this is a grounded system , i still think his concern was in pulling the missing phase on the 3 phase system

 

[jap]

Although the panel is hand written labeled 120/208 single phase, his concern most likely was in pulling the third phase and the source actually being 120/240 3 PH

One would think they would have labeled the panel 120/240 single phase if the transformer outside was actually 240v 3ph.

You almost have to go out of your way to label a panel 120/208 single phase.


JAP>

 

[jap]

I do not think his concern was at the panel. Although the panel is hand written labeled 120/208 single phase, his concern most likely was in pulling the third phase and the source actually being 120/240 3 PH

Though it was clearly stated X3 is the missing Phase and this is a grounded system , i still think his concern was in pulling the missing phase on the 3 phase system

If your talking about Charlie, I think his only "concern" was the negative feedback he was going to receive from the owner when he broke the news to them that some jackleg fed a 3 phase panel with a single phase power.

and,

Was looking for more ammo than just 110.3b to back it up.

At least that's what I'm getting from this.


JAP>

 

[charlie b]

I am beginning to doubt my information sources. I have several photos that prove that the transformer is three phase and that its X3 termination has no conductors attached. The photos I have of the panel are not of the best visual quality. I cannot read the nameplate to confirm whether it is designed as a three phase panel or a single phase panel. I will have to get an electrician to open the cover for me, so that I can resolve this issue once and for all.

Many thanks for all the thoughts and contributions. I will let you all know when I have a resolution.

I will say that the project requirements are likely to force a replacement of the service panel, in order to accommodate the new HVAC equipment that is planned to be installed. So I may not have to convince the owner of the need to correct an NEC violation. Replacement of the panel would automatically cause that issue to become irrelevant.

 

[GeorgeB]

I am beginning to doubt my information sources.

Oh no, SAY IT ISN'T SO! Than never (cough cough) happens to the rest of us.