Transformer NEC 450 Calculator Android

Transformer NEC 450 Calculator

By: ZkDev
NEC 450 transformer OCPD calculator. kVA to conductor sizing. Offline.

Features & Capabilities

NEC transformer overcurrent protection calculator for electricians, apprentices, and electrical engineers. Size primary and secondary OCPD per NEC Table 450.3(B), calculate full-load amps (FLA), and select conductors from Table 310.16 all per NEC 2023 (NFPA 70). This electrical transformer sizing calculator works 100% offline on the job site.

Whether you're sizing overcurrent protection for a 75 kVA, 480-to-208V three-phase transformer, or checking if primary-only protection requires 125% or 300%, this transformer calculator gives you accurate NEC-compliant results in seconds. Use it as your go-to transformer protection reference from kVA rating to OCPD and conductor selection.

TRANSFORMER CALCULATOR FEATURES:
• Primary overcurrent protection per NEC 450.3(B) - 125%/167%/250%/300% rules
• Secondary overcurrent protection per NEC 450.3(B) - 125%/167%/250% rules
• Primary-only and primary+secondary protection methods
• Full-load ampere (FLA) calculation: single-phase and three-phase
• Automatic next-standard-size-up per NEC 240.6(A) with Note 1 logic
• All standard OCPD ratings from 15A to 6000A per NEC 240.6(A)
• Conductor sizing from NEC Table 310.16 (75°C column)
• Copper and aluminum conductor support
• 12 standard kVA ratings from 3 kVA to 1000 kVA
• 5 voltage presets: 120V, 208V, 240V, 480V, 600V
• Single-phase and three-phase support
• NEC article references for every calculation result

NEC REFERENCES INCLUDED:
• NEC Table 450.3(B) - Transformer overcurrent protection (600V or less)
• NEC 450.3(B) Note 1 - Next-size-up rule for primary-only protection
• NEC 240.6(A) - Standard overcurrent device ratings
• NEC Table 310.16 - Conductor ampacity at 75°C

PROTECTION METHOD RULES:
• Primary Only (≤9A): Maximum 167% primary OCPD
• Primary Only (≥9A): Maximum 125% primary OCPD (next size up per Note 1)
• Primary Only (any): Maximum 300% if 125%/167% doesn't correspond to standard size
• Primary + Secondary: Maximum 250% primary, plus 125%/167% secondary OCPD

CALCULATION RESULTS INCLUDE:
• Primary full-load amps (FLA) with formula
• Secondary full-load amps (FLA) with formula
• Primary OCPD size (standard rating per NEC 240.6(A))
• Secondary OCPD size when applicable
• Primary and secondary conductor sizes with ampacity
• Applicable NEC percentage rules and references
• Protection method notes and explanations

PRO FEATURES (one-time purchase):
• No ads - clean interface for professionals
• Save transformer calculation history with labels
• Export calculations as PDF reports for permits and records
• Dark theme support

HOW THE TRANSFORMER CALCULATOR WORKS:
1. Select phase type (single-phase or three-phase)
2. Choose kVA rating from standard sizes
3. Select primary and secondary voltage
4. Choose protection method (primary only or primary + secondary)
5. Select conductor material (copper or aluminum)
6. Get OCPD sizes, conductor recommendations, and NEC references instantly

BUILT FOR ELECTRICIANS ON THE JOB SITE:
This transformer calculator is designed by electricians, for electricians. Enter your transformer parameters, get the correct OCPD size and conductor recommendation instantly - no complicated menus or unnecessary features. One-hand operation, instant results.

PERFECT FOR:
• Licensed electricians sizing transformer protection daily
• Electrical apprentices studying for journeyman exams
• Electrical engineers and designers
• Electrical contractors bidding jobs
• NEC code exam preparation
• Journeyman and master electrician exam study

OFFLINE & PRIVACY:
• Works 100% offline - no internet needed on the job site
• No account required
• No data collection - your calculations stay on your device

Simplify your transformer protection sizing on the job site.

User Growth & Download Statistics

App
By:
ZkDev
Downloads:
71 5
Version:
1.0.6 Last updated: 2026-04-29
Version code:
21
Creation date:
2026-03-08
Publisher country:
KG KG
Permissions:
  • com.google.android.gms.permission.AD_ID Moderate risk
  • android.permission.ACCESS_ADSERVICES_AD_ID Low risk
  • android.permission.ACCESS_ADSERVICES_ATTRIBUTION Low risk
  • android.permission.ACCESS_ADSERVICES_TOPICS Low risk
  • android.permission.FOREGROUND_SERVICE Low risk
  • android.permission.INTERNET Low risk
  • android.permission.WAKE_LOCK Low risk
  • com.android.vending.BILLING Low risk
  • com.google.android.finsky.permission.BIND_GET_INSTALL_REFERRER_SERVICE Low risk
  • android.permission.ACCESS_NETWORK_STATE Safe
  • See more
Size:
24.08MB
Email:
su*****@tradetools.dev
URLs:
Website ,Privacy policy
Full description:
See detailed description
Source:
Google Play Store
Data ingested on:
2026-06-08
Compare stats and ranking:

Contact the developer

Chrome-Stats does not own this Android app. Please use these information below to contact the Android app developer.
Developed by:
ZkDev
Google Play Store
https://play.google.com/store/apps/details?id=com.electools.transformer_calculator
Email:
su*****@tradetools.dev
Website:
https://tradetools.dev/electrical/

Publisher Change History

2026-05-11: su*****@zkdev.ru to su*****@tradetools.dev

Upgrade to see full email

Best Transformer NEC 450 Calculator Alternatives

Here are some Android apps that are similar to Transformer NEC 450 Calculator: