High Leg Voltage

[kwired]

AND a panel that will allow you to install one on the B phase...

This is an under rated aspect of the entre question rendering it, for the most part, moot. For 3 phase panels that are rated 240/120V or 208/120V, ALL of the single pole breakers are "slash rated", meaning they can ONLY be used where the L to G potential is 120V maximum. You CANNOT use slash rated breakers on a 208V to ground potential circuit. The only "straight 240V" rated breakers are 2 pole or 3 pole (and the 2 pole are more expensive than the 120/240V rated 2 pole breakers).

So if you were to WANT to use the B phase to N as a 208V single phase circuit, the only options would be:

• Use a 2 (or 3) pole straight rated breaker and only use one pole, (which is pointless, because you might as well use 240V and NOT use the neutral). This would ONLY make sense if you were somehow stuck with a motor that was rated for only 208V single phase. I have never seen one.
• Buy a 480/240V 3 phase panel and use the entire thing at 240V, which may be confusing to someone in the future. In some brands, you can mix breakers of different voltage ratings, but in reality, you are always buying a 480V rated panel, so it will be bigger and more expensive than an equivalent 240/120V one.

So to be able to use that B phase to neutral, it will cost you MORE than what you might think in one way or another AND be risky for some future person who doesn't understand the ramifications and connects a 120V load to it.

Just use I-Line panels for everything, They have up to 600 volt rated breakers for them.

Not sure if there is 600 volt single pole breakers though, but definitely is 277 volt rated ones, guessing there likely is 347 volt rated single pole breakers though.

 

[kwired]

Every facility needs 120v outlets.
High leg service can be present for mostly three phase, as well as mostly single phase users.

Legacy manufacturing facilities with mostly 3 phase motors often had high leg delta while farm houses with mostly domestic, but had a three phase motor or two that required three phase often got open delta.

For open delta, you really shouldn't put any single phase load on the second transformer.

Irrigation machine applications do not. NEC even ended up adding language exempting those from requiring a 120 volt receptacle.

The guys that do any serious service work to such machines will have portable generator on their service vehicle if they need 120 volts to do a repair. Chances are that generator is also a portable welding machine and can be needed for that use as well at times.

 

[Hv&Lv]

The guys that do any serious service work to such machines will have portable generator on their service vehicle if they need 120 volts to do a repair. Chances are that generator is also a portable welding machine and can be needed for that use as well at times.

Welder/generator was our go to also when I did millwright work.
I figured now days most tools are battery powered.
It's a rarity now when I see a house built there Are drop cords strung out everywhere.

 

[gene6]

The guys that do any serious service work to such machines will have portable generator on their service vehicle if they need 120 volts to do a repair. Chances are that generator is also a portable welding machine and can be needed for that use as well at times.

Talk about odd systems those welder outlets were often 120 DC

 

[kwired]

Talk about odd systems those welder outlets were often 120 DC

Ones I see the "welding machine" is integral to the unit, some are AC welders, some are DC welders, some may have both settings.

Some that I run into have the welding outputs along with 20A 120 volt receptacle, 50 amp 120/240 volt receptacle as well as a 20 amp 480 volt three phase receptacle - which these farmers or service guys typically use as a temp power supply for a center pivot irrigation when necessary. Seems there may be a switch that needs changed and you can not use the 120/240 at the same time as the 480 volt outputs.