A Wire Monkey Labs product

Calculations at the desk. Drawings from the field.

Conductor sizing, panel schedules, motor circuits, transformer and fault current, and one-line risers you can draw standing in front of the gear.

Built for electricians and design engineers who need the answer and the article it came from. Everything runs on the device. One subscription, every feature.

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$5.99/month or $59.99/year · every feature, no tiers · on Google Play and the App Store

The tools

Five things a designer reaches for daily, and a riser builder for the room itself.

Everything on device. No account, no sign-in, no signal required.

Circuit

Conductor sizing against the two-step derate and termination rule, voltage drop with real impedance at power factor, raceway fill, and parallel sets. Shows the derivation, not just the answer.

Loads

FLA, amps, VA or kW at any voltage and phase, with a running tally you build straight off a mechanical schedule. Flags continuous loads and sizes the breaker at 125 %.

Motors

Table full-load current, branch protection, overload, disconnect and NEMA starter. Keeps table FLC and nameplate FLA in their separate jobs, because they are not interchangeable.

Panels

Schedules from a six-circuit load center to a four-section switchboard. Phase rotation across sections, load classification rollup, noncoincident handling, and a design review.

Power

Transformer sizing and primary protection, with available fault current from a complex impedance network rather than a lookup table.

Riser

Walk a service and record it as you go. Pick the utility source, then work downstream — the app draws the one-line. A multi-story building is drawn the other way up, as a building riser: floors stacked the way the building stacks them, service at the bottom, feeders climbing. Photos, existing / new / demo status, and a printable sheet.

The kind of thing it catches. A 25 kW charger at 480 V three-phase draws 30.1 A. That points at a 35 A breaker, and 35 A is wrong — EV supply equipment is a continuous load, so it sizes against 125 % of the draw. The answer is 40 A. Ampsheet says so, and cites the article that says so.

The Circuit screen showing a conductor result with ampacity, fill and voltage drop — Circuit — the result, with the numbers that produced it.

The Motors screen showing full-load current, protection and starter sizing — Motors — table FLC and nameplate FLA kept apart.

The Riser screen, showing a service recorded downstream from the pad transformer to a panel — Riser — recorded downstream, one piece of gear at a time.

Output

What comes off the phone.

Exports are for field reference, coordination and RFIs. Every sheet says so on its face.

An exported riser sheet for a 3000 A service, twenty-five pieces of gear drawn top to bottom on 11 by 17, with twelve feeders off the switchboard, conventional symbols, feeder callouts and demolition shown dashed — A 3000 A service exported straight from the phone — twenty-five pieces of gear from the utility pad down to the RTU disconnects, with twelve ways off the switchboard: two dry transformers to 208, two mechanical panels, an MCC, an emergency leg on a transfer switch, the air compressor and the elevator. New work is drawn heavy, demolition dashed, and the small squares mark gear with photos attached. The panel schedule beside this is MP-1, third from the left. The sheet is chosen from the drawing: letter where it fits, 11 × 17 where a service is large enough that letter would shrink it past reading. One page either way.
Open the full sheet (PDF)

An exported 42-circuit 480Y/277 mechanical panel schedule with seven load classifications, demand factors and a design review — MP-1 from the survey beside it — a 42-circuit 480Y/277 mechanical panel with four roof units, an elevator, an EV charger, 277 V lighting and the shop feed. Seven load classifications, each with its own demand factor. The review underneath is the app's own reading of what was entered: it flagged a unit heater sitting at 84 % of its breaker, and dropped the heating total out entirely as the smaller half of a noncoincident pair with cooling, citing the article for doing it. One section, one page.
Open the full sheet (PDF)

An exported building riser for a six-story tower on 11 by 17: seven horizontal floor bands from the service at the bottom through basement, levels one to four and the roof, with thirty-two pieces of gear standing on the floor lines and feeders climbing between them in vertical shafts — The same builder, on a six-story tower — thirty-two pieces of gear, basement to roof, on one 11 × 17 sheet. A building riser is not a one-line turned sideways: the floors stack in the order the building stacks them, the service sits at the *bottom*, and the feeders climb. Vertical position means floor, not depth in the survey, so LP-3B is drawn on level 3 even though it is fed from LP-2A a floor below rather than from the switchboard.

Each gap between columns is a shaft, and it is only as wide as the feeders actually running in it — the one carrying six risers off MSB-1 is wide, the ones carrying none are not. ATS-1 shows both of its supplies: normal from the switchboard into one pole, standby from GEN-1 into the other. The generator has no conductor running into it, because nothing in the building feeds a generator.
Open the full sheet (PDF)

Mark-up

Then redline it, on the phone, and send the RFI.

Open any sheet the app made, draw on it, export it again. Boxes, circles, arrows, freehand and text, in four colors, with undo. The marks go into the PDF as vectors — they stay sharp at any zoom because nothing is ever rasterized.

The MP-1 panel schedule marked up as RFI 014, with a circled circuit, a boxed classification row, two spare spaces held, and a numbered legend — MP-1 again, on its way to an RFI. The unit heater the app flagged is circled, the noncoincident row is boxed with the question written out, and two spaces are held for a fifth roof unit. The session title prints as a stamp. Same sheet, same disclaimer, one more export — no desktop, no round trip.
Open the marked-up sheet (PDF)

How it is built

Three code editions, read rather than assumed.

Ampsheet supports NEC 2020, 2023 and 2026, and translates article numbers between them — a rule that moved between editions is shown under the number your jurisdiction actually uses. Where we have not confirmed a citation for the edition you selected, the app marks it instead of guessing.

Adoption varies by jurisdiction. Ampsheet supports these editions; it does not know which one your inspector enforces, and it says so.

Six commitments behind every result.

These are the terms Ampsheet is built on. They do not change from one update to the next.

It runs on your device

No account, no sign-in, no sync. Your work is written to local storage and stays there — none of it is ever sent anywhere. Nothing to breach, nothing to sell, nothing that stops working when we do.

It works with no signal

Every calculation runs locally. A basement electrical room, a job site, a gym with no bars — those are exactly the places a reference tool has to keep working, so that is the condition we build for first.

It shows its work

Results come with the derivation and the citation, so you can check the reasoning instead of trusting a number. We do not reproduce copyrighted source text — we point at it precisely enough that you can read it in your own copy.

It is marked for what it is

A calculation is not a professional judgment, and we never let one look like the other. Where our output could be mistaken for an authoritative document, it says on its face that it is not one.

One subscription, every feature

No tiers, no add-ons, no upsell inside the app, no feature held back to create a reason to charge again. One subscription unlocks all of it.

We say what we did not check

Verification has an edge, and pretending otherwise is the most common lie in this category. Where a result rests on an assumption we cannot verify — equipment marking, an installation detail, a local amendment — the app tells you, in that result, at that moment.

What that costs us, so you know we mean it. Verifying Ampsheet's electrical data against three editions of the code book — article by article, table by table, cell by cell — turned up real defects in our own work: a conduit table missing two sizes, a conductor rule applied to the wrong load, a protective-device ceiling rounded the wrong direction.

We would rather tell you that than let you find it. Every one is written down, with the page it was found on, and guarded by a test so it cannot come back.

NEC and National Electrical Code are registered trademarks of the National Fire Protection Association. NEMA is a trademark of the National Electrical Manufacturers Association. Wire Monkey Labs LLC is not affiliated with, endorsed by, or sponsored by NFPA, NEMA, or any standards body. References to code articles are descriptive only, and Ampsheet does not reproduce the text of any code or standard.

Before you rely on it

What Ampsheet is not.

Ampsheet is a reference and calculation tool. It is not an engineering service, and nothing it produces is a sealed or approved document. You are responsible for verifying every result against the code edition adopted in your jurisdiction, any local amendments, and the actual nameplate data of the equipment involved.