Exposed vs concealed runs of fire-protection lines above ceilings: fire-electrical conduit wiring is treated as "exposed (surface)"; fire water pipes are "concealed" per plumbing terminology — two opposite calibers

Topic Positioning

Determining whether fire lines laid above ceilings are "exposed (surface)" or "concealed". The key: "fire lines" fall into two classes with opposite code calibers — conduit wiring of fire-electrical circuits is exposed per electrical codes; fire water pipes (sprinkler/hydrant) are concealed per plumbing terminology. For design classification, BOQ item-characteristic description, and quota assembly.

Core Conclusions

1. Fire-electrical conduit wiring (fire alarm, linkage, fire-power circuits) -> treated as "exposed (surface)" above ceilings

Logic: concealed = in conduit within non-combustible structure with cover-thickness requirements; ceilings do not meet this, and the code expressly classifies "laid in ceilings" as exposed.

• GB 50016-2014 (2018 edition) Code for Fire Protection Design of Buildings, Clause 10.1.10 (Items 1-2 mandatory): "Fire power circuits shall meet continuous-supply needs in fire, installed as follows: 1 Exposed (including in ceilings): in metal conduit or enclosed metal raceways, with fire-protection measures; flame-retardant or fire-resistant cables in cable shafts/trenches need no metal conduit/raceway; mineral-insulated non-combustible cables may run exposed directly. 2 Concealed: in conduit within non-combustible structure with cover not less than 30 mm. 3 Fire power circuits should be laid separately from other circuits in different shafts/trenches; where truly difficult and sharing, they shall be on opposite sides, and fire power circuits shall use mineral-insulated non-combustible cables."
• GB 50116-2013 Clause 11.2.3: "Concealed runs shall use metal conduit, flexible (metal) electrical tubing, or rigid plastic conduit of Class B1 or above, within non-combustible structural layers with cover preferably >=30 mm; exposed runs shall use metal conduit, flexible (metal) electrical tubing, or enclosed metal raceways. Mineral-insulated non-combustible cables may run exposed directly." Commentary: "Rigid plastic conduit of Class B1 or above is allowed only for concealed runs; exposed runs may use only metal conduit or raceways."
• Corroboration (mandatory): GB 51348-2019 Standard for Electrical Design of Civil Buildings, Clause 8.1.6: "Distribution circuits run exposed in combustible attics and enclosed ceilings shall use metal conduit or raceways." Commentary lists combustibles: timber structures, timber ceiling boards, PVC boards, foam acoustic panels, PC panels, membranes; inspection point: rigid plastic conduit/raceways there violate the mandatory clause.
• Local consistency: DB37 5056-2016 Clause 6.2.3 (Items 1-2 mandatory): fire power circuits exposed (including in ceilings) shall be in metal conduit or enclosed metal raceways with fire protection; concealed in non-combustible structure with cover >=30 mm.

Pricing implications (three actions): (1) the conduit BOQ item characteristic shall state the form (exposed/concealed); above-ceiling conduit is described as "exposed" (GB/T 50856-2024 Table D.12.1 "conduit and wiring", code 030412); (2) assemble under "exposed conduit" sub-items — quota conduit sub-items are generally split exposed/concealed; above-ceiling runs take exposed, per the applied volume's notes; (3) fire-protection measures on above-ceiling metal conduit/raceways (wrapping or intumescent coating) are mandatory accompaniments of "treated as exposed" — do not omit in assembly.

2. Fire water pipes (sprinkler, hydrant) -> terminologically "concealed"

• GB 50015-2019 Standard for Building Water Supply and Drainage, Clause 2.1.22: "concealed installation: indoor pipes arranged in wall chases, shafts, or trenches, or hidden by building decoration." Clause 3.6.13: "Concealed water pipes shall: 1 not be cast directly into structural layers; 2 mains and risers laid in ceilings, shafts, or duct spaces, branches in ceilings, floor/cushion layers, or wall chases; 3 branches in cushions or chases preferably <=25 mm OD; 4 materials plastic, metal-plastic composite, or corrosion-resistant metal; 5 no detachable joints in cushion/chase runs; flexible pipes should feed fixtures from manifolds without intermediate fittings, with both ends exposed."
• Cross-discipline consistency: HG/T 20657-2013 Clause 7.1.5: "concealed piping: pipes hidden invisible in trenches, chases, ceilings, dedicated shafts"; GB/T 50680-2012 Clause 10.4.3: "enclosed installation: pipes installed within ceilings, cabinets, trenches, shafts."
• Pricing note: this "concealed" is a "hidden by ceiling, invisible" classification, not embedded construction — above-ceiling fire water pipes are still installed overhead on hangers; pipe sub-items are generally by material/joint/diameter without exposed/concealed split, so there is no either-or; the classification actually affects painting/anti-corrosion (above-ceiling = non-exposed; finish and color bands per design), access panels, and supports (per the applied volume).

One-line contrast: above ceilings — fire-electrical conduit = exposed (with exposed-type fire protection); fire water pipes = concealed (a visibility classification not affecting sub-item choice).

Applicable Boundaries

• Classify the object first: fire-electrical conduit wiring and fire water pipes use different terminologies — do not mix. Electrical "exposed/concealed" carries structural mandates (concealed cover >=30 mm; exposed fire protection); plumbing "exposed/concealed" is visibility classification — different meanings.
• "Above-ceiling as exposed" guides design classification, BOQ characteristics, and assembly direction; specific sub-item settings and above-ceiling notes follow the applied quota volume.
• Fire-protection measures on exposed metal conduit/raceways follow the design (wrapping or coating); this card does not replace design documents.
• Clause texts per current GB 50016-2014 (2018 edition) 10.1.10, GB 50116-2013 11.2.3, GB 51348-2019 8.1.6, GB 50015-2019 2.1.22/3.6.13.

Further Reading

• Electrical: GB 50016-2014 (2018 edition) Clause 10.1.10 and commentary (Items 1-2 mandatory); GB 50116-2013 Clause 11.2.3 and commentary; GB 51348-2019 Clause 8.1.6 (mandatory, with technical and inspection points); local corroboration DB37 5056-2016 Clause 6.2.3.
• Water: GB 50015-2019 Clauses 2.1.22 (term) and 3.6.13 (rules with commentary); HG/T 20657-2013 Clause 7.1.5; GB/T 50680-2012 Clause 10.4.3.
• Measurement: GB/T 50856-2024 Appendix D, Table D.12.1 "conduit and wiring" (code 030412); when assembling, check the applied volume's conduit (exposed/concealed) sub-item notes and above-ceiling provisions.