Sanctuary lamp

A sanctuary lamp, chancel lamp, altar lamp, everlasting light, or eternal flame is a light that shines before the altar of sanctuaries in many Jewish and Christian places of worship. Prescribed in Exodus 27:20-21 of the Torah, this icon has taken on different meanings in each of the religions that have adopted it. The passage, which refers to prescriptions for the tabernacle, states:
In Judaism, the sanctuary lamp is known as a Ner Tamid (Hebrew, “eternal flame” or “eternal light”), Hanging or standing in front of the ark in every Jewish synagogue, it is meant to represent the menorah of the Temple in Jerusalem, as well as the perpetual fire kept on the altar of burnt offerings before the Temple. It also symbolizes God's eternal presence, and is thus never extinguished, and to draw parallels between God and fire or light as emphasized throughout Exodus in the Torah.
These lights are never allowed to dim or go out, and in case of electric problems, alternative emergency power is used to prevent them from extinguishing.
Though once fuelled by oil, most today are electric lights.
The eternal light is central to one of many stories behind the celebration of the Jewish festival of Hanukkah. When the ancient Maccabees rebelled and reclaimed the Temple in Jerusalem, they rekindled the eternal light. However, there was only enough oil to keep the flame burning for one day, and it took eight days to bring new oil. Miraculously, according to the narrative in the Talmud, the flame continued burning until new oil arrived.
Modern Jewish celebrations of Hanukkah include lighting a Hanukkah menorah (Hanukkiyah), which has nine branches. This includes the shamash used to light the other eight flames (candles or oil wicks), evoking the story.
Some Christian churches have at least one lamp continually burning before the tabernacle, not only as an ornament, but for the purpose of worship. The General Instruction of the Roman Missal of the Catholic Church, for instance, states (in 316): “In accordance with traditional custom, near the tabernacle a special lamp, fueled by oil or wax, should be kept alight to indicate and honor the presence of Christ.” The sanctuary lamp, also called a chancel lamp, is placed before the tabernacle or aumbry in Roman Catholic churches as a sign of Jesus’ presence within, and in Old Catholic and Anglican churches as a sign that the Blessed Sacrament is reserved or stored. It is also found in the chancel of Lutheran and Methodist churches to indicate the presence of Christ in the sanctuary, as well as a belief in the Real Presence of Christ in the Eucharist. The sanctuary lamp may also be found in Eastern Orthodox Churches. Other Christian denominations burn the lamp to show that the light of Christ always burns in a sin-darkened world. A main influence from Judaism in the Old Testament is when God instructed Moses to have a lamp with pure oil perpetually burn in the Tabernacle (Exodus 27:20-21). This is the precedent for the Catholic custom of burning a candle before the tabernacle, which should be immobile and locked to prevent theft and Host desecration, as well as whenever transporting the Sacrament anywhere.
Such sanctuary or tabernacle lamps are most often coloured red, though this is not prescribed. This serves to distinguish this light from various other votive lights within the church. In the Catholic Church, red is widely used despite the preference for white expressed by Fortescue. The custom of multiple lights in odd numbers (i.e., three, five, seven, or more) in place of a single lamp has become rarer, though it is still seen in some older Catholic churches and in Eastern Christianity. The lamp may hang by rope or chain over the tabernacle or near the entry of the sanctuary, or affixed to a wall; it may also be on a ledge or the altar gradine right beside the tabernacle, or on its own nearby stand placed on the floor, as seen in the image of St. Martin's Church, Kortrijk, Belgium, in the article Church tabernacle. Oil lamps or candles may be used, while electric ones are seen.
In the United States, the Boy Scout Jewish religious emblem, a medal earned by scouts for meeting certain requirements of religious activity and education, is called the Ner Tamid.
A song by Matisyahu called Aish Tamid ("eternal flame") that appears in his albums Shake Off the Dust... Arise (2004) and Live at Stubb's (2006).