# Relay coil and it's normally closed contact question?

**URL:** <https://forumautomation.com/t/relay-coil-and-its-normally-closed-contact-question/1583>\
**Category:** Electrical\
**Tags:** relay\
**Created:** [December 21, 2016, 8:47am UTC](https://forumautomation.com/t/relay-coil-and-its-normally-closed-contact-question/1583 "2016-12-21T08:47:22Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![servoman11111](https://forumautomation.com/letter_avatar_proxy/v4/letter/s/a88e4f/32.png) [@servoman11111](https://forumautomation.com/u/servoman11111)\
**Post date:** [December 21, 2016, 8:47am UTC](https://forumautomation.com/t/relay-coil-and-its-normally-closed-contact-question/1583/1 "2016-12-21T08:47:22Z")

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assume that we have a relay: what will happen if we connected the **[relay coil](https://forumelectrical.com/what-is-an-overload-relay-function-types-uses/)** with the normally closed contact (series connection)of the relay then we applied electricity through the normally closed contact to the coil ?

 ![1 - Copy](https://cdn.forumautomation.com/original/2X/c/c56b33a610a8733c359e5ee8bd84a963ee91f793.jpeg)

**Reference Image Provided by the Respondent**

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**Author:** ![automate](https://forumautomation.com/letter_avatar_proxy/v4/letter/a/51bf81/32.png) [@automate](https://forumautomation.com/u/automate)\
**Post date:** [December 22, 2016, 12:29am UTC](https://forumautomation.com/t/relay-coil-and-its-normally-closed-contact-question/1583/2 "2016-12-22T00:29:20Z")

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It will act like a not gate.

When there is no electricity in the first coil it will excite the coil of second relay.

When there is electricity in the first coil it will deenergize the coil of second relay.

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**Author:** ![carl\_e](https://forumautomation.com/letter_avatar_proxy/v4/letter/c/94ad74/32.png) [@carl\_e](https://forumautomation.com/u/carl_e)\
**Post date:** [December 25, 2016, 1:48am UTC](https://forumautomation.com/t/relay-coil-and-its-normally-closed-contact-question/1583/3 "2016-12-25T01:48:04Z")

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The NC contacts are ‘made’, so when the coil is energized, the contacts open. As the contacts open, the coil de-energizes, so the contacts begin to close, but as the contacts close and are ‘made’ again, the coil re-energizes.

The relay will chatter continuously (and sound like a buzzer), cycling between on and off until it destroys itself in a short time.

This relay is not wired for functionality, it is miswired (Power through the NC contacts driving the coil).

In a functional circuit, when an external circuit drives the coil, then the coil’s NC contact will ‘invert’ the state of the coil as poster automate suggests. Coil = ON or logic 1, NC contacts = Open/Off or logic 0.

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**Author:** ![Rabert](https://forumautomation.com/user_avatar/forumautomation.com/rabert/32/6784_2.png) [@Rabert](https://forumautomation.com/u/Rabert)\
**Post date:** [July 25, 2026, 1:25pm UTC](https://forumautomation.com/t/relay-coil-and-its-normally-closed-contact-question/1583/4 "2026-07-25T13:25:10Z")

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## What is normally closed in a relay module?

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**Author:** ![TSRS](https://forumautomation.com/user_avatar/forumautomation.com/tsrs/32/8023_2.png) [@TSRS](https://forumautomation.com/u/TSRS)\
**Post date:** [July 25, 2026, 1:26pm UTC](https://forumautomation.com/t/relay-coil-and-its-normally-closed-contact-question/1583/5 "2026-07-25T13:26:31Z")

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Normally Closed (NC) refers to a relay contact that is closed as the relay coil is de-energized.

In simple terms, when the relay is not activated, the NC contact permits current to pass ensuring the circuit is complete.