ECN Forum Forums General Topics of the Trade General Discussion Area using a 3 phase panel on a single phase system?

I agree with the other Members - do not use the 3 Phase Panelboard on a Single Phase 3 Wire System.
Beside the Listing Issues & Code Issues, it is really sloppy; especially where Multiwire Circuitry &/or 2 Pole L-L Circuitry is used.

Going the opposite way - using a Single Phase 3 Wire Panelboard on a Three Phase System, has a few possible applications, which include:

Example 1:
120/240V 1 Phase 3 Wire Panelboard on 240/120V 3 Phase 4 Wire Delta System; connecting Lines A & C + Common Neutral to 1 Ph. Panelboard.
This has been done where 1 Phase loads are needed only.
No Wild Phase (Hi Voltage to Ground Phase) issues in the Panelboard.

Example 2:
120/240V 1 Phase 3 Wire Panelboard(s) on 208Y/120V 3 Phase 4 Wire Wye System; connect (2) Ungrounded Feeders + Star Point (Neutral) to Panelboard.
This is somewhat sloppy (IMO) for Commercial / Industrial stuff, however is very common in Multi-Family Dwellings, per a "Network" Service design.

Example 3:
120/240V 1 Phase 3 Wire Panelboard(s) on 240V Corner Grounded Delta System; connect the (2) Ungrounded Conductors - Phases / Lines A & C to the Bus Kit, then connect the Grounded Conductor - Phase / Line "B", to the Isolated Neutral kit.
Line "B" is used as a Common, where (2) 1 Phase 2 Wire loads are connected, as described in the following Illustration:



Refer to Corner Grounded 3 Phase 3 Wire Delta, at the Tech. reference section for more information.

Forgot to add...

The latter example (Example #3) would require 1 Pole devices with a Single Pole AIC rating at no less than 240V.

Furthermore, the Panelboard must be Listed for such use.

Also, this setup _SHOULD NOT_ be used where the Neutral Kit is connected to an Ungrounded Conductor.

This setup was common "Back In The Old Days" (installed up to circa 1980), and may still be found existing in "Older" Industrial areas.


-- Scott