Candle Lighting: Candles Only?

Rav Yosef Jacobovitz

Yitzchak brought Rivka home and saw a special blessing in Rivka’s mitzvah of hadlakas neiros, similar to his mother, Sarah, in that it was not extinguished from shabos to shabos.

What is the minimum requirement as a fuel?

Shulchan Aruch –  all
oils and waxes are permitted; yet, olive oil is preferable based on mesorah.

Mishna Berurah – olive oil is preferable only because it
kindles well. If olive oil isn’t readily available, one may use wax candles.

Rav Moshe Feinstein- the clearest flame is the most preferred.

The Steipler Gaon – used wax candles since it lit better or
equal to oil.

The Baal HaTurim – Parshas Tetzave- Tetzave is the gematria of
nashim tzavei– that they too should light with oil.

Rav Shmuel Kamenetzky- based on above, one would need hataras nedarim to change their minhag from olive oil to candles. However, if one does
not have a particular minhag, it is not necessary
to use specifically olive oil.

When one cannot light [i.e. a hospital]

Electric bulbs: Rav Chaim Ozer Grodzensky- an incandescent bulb
is a regular flame.

Rav Henkin agrees.

Rav Shlomo Zalman Auerbach distinguishes between a battery
operated device [i.e. a flashlight] where the entire energy source is present
and ignited prior to shabos. A wall based ac current has only a small portion
of the energy at the point of the outlet.