Disclaimer

Conduitwise is a planning tool, not the code and not a substitute for an electrician. Confirm every value against the NEC edition your jurisdiction has adopted, follow local amendments and use a licensed electrician for installations.

Planning tool, not the code

The tables on this site (NEC Chapter 9, Tables 1, 4 and 5) were cross-checked against published copies of the 2017 edition. Other editions or local amendments may differ. An inspector’s decision always wins.

What we tested, and what we did not

We tested 300 random wire mixes in EMT, PVC Schedule 40 and rigid metal conduit against separate arithmetic, and that the result prints on one page. We did not test your jurisdiction’s rules, insulation types other than THHN, THWN and THWN-2, derating for heat, or the 60% exception for short nipples.

What was tested, 300 random wire mixes and one-page printing, and what was not, such as your jurisdiction, other insulation types and derating

Electrical safety

Switch off and lock out the circuit before you work, never work on live parts, and check whether a permit or inspection applies. If you are not trained, hire a licensed electrician.

Electrical safety: switch off and lock out first, do not work live, permits and inspection may apply, and hire a licensed electrician

See also the terms of use and the privacy policy.

Frequently asked questions

Is the calculator the same as the code?

No. It applies the tables to your numbers. The code is the authority.

Which edition should I use?

The one your jurisdiction has adopted.

Where do I report a mistake?

Use the contact page.

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