The installation manuals show the following for a single phase system:

Two conditions must be satisfied:

1. V-LN <347V
2. V-LL<600V

• For a three phase system running at 347V-LN, V-LL=sqrt(3)*600V and both conditions are met.
• For a single phase system with 180 degree separation, if VLN=347V condition 1 will be satisfied, condition 2 fails (347V*2=694V).
• If V-LL is limited to 600V, V-LN=600V/2=300V and both conditions are met.

Therefore, 600V-LL can be used for a single phases system.

The statement in the installation guide states 277V-LN/554V-LL because 277V-LN is a standard power level. This was put in to try and make things simpler for the end user although it could cause some confusion.