<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2004-04-15</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000038725</issuerCik>
        <issuerName>FRANKLIN ELECTRIC CO INC</issuerName>
        <issuerTradingSymbol>fele</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001275975</rptOwnerCik>
            <rptOwnerName>FERGUSON DIANA SUE</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SARA LEE CORP</rptOwnerStreet1>
            <rptOwnerStreet2>70 W MADISO ST</rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60602</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <ownerSignature>
        <signatureName>Gregg C. Sengstack, Power of Attorney for Diana S. Ferguson</signatureName>
        <signatureDate>2004-04-21</signatureDate>
    </ownerSignature>
</ownershipDocument>

