The main liturgical book on this is “Holy Communion and the Worship of the Eucharist Outside of Mass”. In Australia it was published published by E.J. Dwyer, Sydney, 1975, ISBN 0-85574-401-4. It can also be found in The Rites Volume One, Liturgical Press, 1990, ISBN: 0-8146-6015-0, starting at page 633.
It has:
“85. For exposition of the blessed sacrament in the monstrance, four to six candles are lighted, as at Mass, and incense is used. For exposition of the blesed sacrament in the ciborium, at least two candles should be lighted and incense may be used.”
This is a little confusing, because for Mass two candles can be used. The Ceremonial of Bishops is clearer:
“1104 For exposition of the blessed sacrament with a monstrance, the followed are to be prepared: … four or six candles;”
(Ceremonial of Bishops, Liturgical Press, 1989, ISBN 0-8146-1818-9, page 297.)
Another document to consider is the 2004 Instruction Redemptionis Sacramentum, numbers 129-141. Particularly important is “[138.] Still, the Most Holy Sacrament, when exposed, must never be left unattended even for the briefest space of time. It should therefore be arranged that at least some of the faithful always be present at fixed times, even if they take alternating turns.”
Even more recently, questions and answers have been published in Notitiae, a journal published by the Congregation of Divine Worship and the Discipline of the Sacraments. In the September-October 2006 edition, page 493, it has article headed “Questions on Adoration of the Blessed Sacrament [footnote Extracts courtesy of the Bishops’ Committee on the Liturgy of the United States Conference of Catholic Bishops]”. It goes to question 30, whereas the full book has 31 questions. It can be purchased from
usccbpublishing.org/productdetails.cfm?sku=5-595 . It includes:
“25
In order to enhance security, may the Blessed Sacrament be exposed behind a glass window?
No. … Such arrangements often result in the appearance of a “glass tabernacle”, which is forbidden.”
“24.
In those places where perpetual adoration of the exposed Blessed Sacament take place, scheduling is often a great challenge. If a person misses an assigned hour for adoration of the exposed Sacrament, can a door or a drape be erected so that the exposed Sacrament can be temporarily closed off from public view?
No. The use of drapes or doors to shield the monstrance, even for a short period of time, is not the required reposition of the Blessed Sacrament. The Blessed Sacrament may never be left exposed when no one is present for prayer and adoration. “Every effort should be made to ensure that there should be at least two people present. There must absolutely never be periods when the Blessed Sacrament is exposed and there is no one present for adoration”. [footnote 30: Roman Ritual, Holy Communion and the Worship of the Eucahrist Outside of Mass, n. 88]. “If a period of uninterrupted exposition is not possible, because of too few worshipers, the Blessed Sacrament may be replaced in the tabernacle during periods which have been scheduled and announced beforehand.
This reposition may not take place more often than twice during the day, for example, about noon and at night”. [footnote 31: Congregation for Divine Worship and the Discipline of the Sacraments,* Responsum ad dubium received by the USCCB Committee on the LIturgy, July 1995, published in Solemn Exposition of the Holy Eucharist, Washington, DC, 1996 (=
Liturgy Documentary Series, 11) pp. 36-37.”
I think footnotes 31 and 30 are mixed up.
The “about noon and at night” quote seems to be from Holy Communion and the Worship of the Eucahrist Outside of Mass, n. 88. Although the version published in The Rites has “at midday and at night”.
The “at least two people present” quote is not in HCWEOM n. 88, so I guess it is from 1995 Responsum ad dubium.
The requirement for a taberancle lamp is in Canon 940 of the Code of Canon Law: “A special lamp to indicate and honor the presence of Christ is to burn at all times before the tabernacle in which the Most Holy Eucharist is reserved.”
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