Neros Shabbos

The Gemarah Shabbas (23b) says if a person can not afford both wine for kiddush and a candle for Shabbos then buying a candle takes precedence because it is needed for shalom bayis.  Asks the Chayeh Adam, why do we need a new reason of shalom bayis, since the candles are lit erev Shabbos and kiddush is only said on Shabbos, of course the candle take precedence, since it is the mitzvah done first?  

Tosfos in Shabbos (25b) has an opinion that one does not say a beracha on lighting nerot Shabbat.  One of the arguments of Tosfos is that one does not need to actively light a candle for Shabbos, it suffices to have a candle lit for Shabbos.  Rabbenu Tam argues and says one has to actively light a candle for shabbos and his proof is from a Gemarah (23b) here Rav Yosef told his wife not to light the nerot Shabbos to late since it says ״לֹא יָמִישׁ עַמּוּד הֶעָנָן יוֹמָם וְעַמּוּד הָאֵשׁ לָיְלָה״ — מְלַמֵּד שֶׁעַמּוּד עָנָן מַשְׁלִים לְעַמּוּד הָאֵשׁ וְעַמּוּד הָאֵשׁ מַשְׁלִים לְעַמּוּד הֶעָנָן.  Rashi says עמוד הענן - של יום משלים אורו לעמוד האש שהיה עמוד האש בא קודם שישקע עמוד הענן אלמא אורח ארעא בהכי.  The Gemarah then continues that one can't light to early either.  Says Rabbenu Tam, we see there is a proper timeframe for lighting, it doesn't suffice to merely have a candle lit?  Rav Yosef Engel (Beis Haotzer Klal 66) points out according to the first approach in Tosfos, the mitzvah is to have a candle lit on Shabbos . In light of that approach the mitzvah of neros Shabbos is fulfilled on Shabbos when the house is illuminated and the mitzvah starts at the same time as kiddush and we don't have the question of the Chayeh Adam.  But according to Rabbenu Tam that the mitzvah is the act of lighting, the question still stands. 

It is noteworthy that the Magid Mishna (Chanukah 4:5) notes the Rambam understands the Gemarah of not to light too early or too late is referring to the Chanukah candles, not neros Shabbos and this would knock off Rabbenu Tam's proof.  However, this is very difficult since it was the wife of Rav Yosef lit would indicate it is neros Shabbos, see there in Even Haezel that maybe it was erev Shabbos Chanukah, and she was lighting later to light Chanukah candles later, וצ"ע.  

The Mishpitay Uziel (volume 1 #7) uses this debate as a starting point for the discussion if one can fulfill neros Shabbos with electric lights.  According to the approach that one just needs light to exist in the house it should suffice but if one needs an act of kindling a fire, he does not believe merely turning on the light is considered lighting the fire.  

(See also the Griz in the Grach stencil on the opinion of the Rambam and Mishpitay Uziel.)