Plumbing New Feature

Introducing Plumbing: Water Supply, Drainage & Vent Sizing

OhmWorks now covers plumbing alongside electrical — a new tab with real calculators sourced from the Revised National Plumbing Code of the Philippines.

OhmWorks started as an electrical cable sizing app across PEC, AS/NZS, and NEC. It just grew a fourth tab: Plumbing, with three real calculators sourced directly from the Revised National Plumbing Code of the Philippines (RNPCP 1999).

What's in the Plumbing Tab

• Water Supply Fixture Units — tally total WSFU across every fixture in a job, split by private or public use, sourced from Table 6-5
• Drainage (DFU) Pipe Sizing — minimum drainage pipe size from total fixture unit load, vertical or horizontal, with a max-length check on vertical stacks (Table 7-5)
• Vent Pipe Sizing — minimum vent size from fixture units and run length, plus the "not less than half the drain diameter served" rule

Why These Three First

Every table behind these three calculators was read with high confidence from the source document — clean, well-formatted, non-rotated pages. One table (the final water meter/pipe sizing table, keyed to pressure range) was deliberately left out after two careful attempts to transcribe it, because the scan quality wasn't reliable enough to trust with a real installation's pipe sizing. That's documented directly in the app rather than guessed at.

Same App, Same Discipline

Plumbing follows the exact same rules the electrical calculators already follow: real data, cited to its source table and page, with anything unverified clearly flagged rather than quietly assumed. It's built into the same shared app — so it's already live on the web version, and will be part of the next mobile update too.

Try it now in the Plumbing tab.

Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks

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