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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-01-30</periodOfReport>

    <issuer>
        <issuerCik>0000105634</issuerCik>
        <issuerName>EMCOR GROUP INC</issuerName>
        <issuerTradingSymbol>EME</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001209469</rptOwnerCik>
            <rptOwnerName>RYAN JERRY E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>6171 S. MARION AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>TULSA</rptOwnerCity>
            <rptOwnerState>OK</rptOwnerState>
            <rptOwnerZipCode>74136</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-01-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2349</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>31965</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Jerry E. Ryan Recovable Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents restricted stock units (&quot;RSUs&quot;) issued in respect of already outstanding RSUs as a consequence of a dividend paid on the Company's common stock on January 30, 2019.  The RSUs issued on January 30, 2019 are subject to the same vesting and forfeiture provisions as the RSUs in respect of which they have been issued.</footnote>
        <footnote id="F2">Includes shares issuable in respect of RSUs.</footnote>
        <footnote id="F3">The reporting person transferred these shares to the Jerry E. Ryan RevocableTrust with respect to which the reporting person is the trustee and settlor and certain family members of the reporting persons are beneficiaties.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>By Maxine L. Mauricio, Attorney-in-Fact</signatureName>
        <signatureDate>2019-01-31</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2019-01-30
0000105634
EMCOR GROUP INC
EME
0001209469
RYAN JERRY E
6171 S. MARION AVENUE
TULSA
OK
74136
1
0
0
0
Common Stock
2019-01-30
4
A
0
2
0
A
2349
D
Common Stock
31965
I
By Jerry E. Ryan Recovable Trust
Represents restricted stock units ("RSUs") issued in respect of already outstanding RSUs as a consequence of a dividend paid on the Company's common stock on January 30, 2019.  The RSUs issued on January 30, 2019 are subject to the same vesting and forfeiture provisions as the RSUs in respect of which they have been issued.
Includes shares issuable in respect of RSUs.
The reporting person transferred these shares to the Jerry E. Ryan RevocableTrust with respect to which the reporting person is the trustee and settlor and certain family members of the reporting persons are beneficiaties.
By Maxine L. Mauricio, Attorney-in-Fact
2019-01-31