Exhibit 3.1

CERTIFICATE OF DESIGNATION

OF

SERIES A JUNIOR PARTICIPATING PREFERRED STOCK

OF

INTEGRATED ELECTRICAL SERVICES, INC.

(Pursuant to Section 151 of the

General Corporation Law of the State of Delaware)

Integrated Electrical Services, Inc., a corporation organized and existing under the General Corporation Law of the State of Delaware (hereinafter called the “Company”), hereby certifies that the following resolution was duly adopted by the Board of Directors of the Company as required by Section 151 of the General Corporation Law of the State of Delaware at a meeting duly called and held on January 24, 2013:

RESOLVED, that pursuant to the authority granted to and vested in the Board of Directors of the Company (hereinafter called the “Board of Directors” or the “Board”) in accordance with the provisions of the Company’s Second Amended and Restated Certificate of Incorporation, as amended to date (hereinafter called the “Amended and Restated Certificate of Incorporation”), the Board of Directors on January 24, 2013 adopted the following resolution creating a series of shares of Preferred Stock, par value $0.01 per share, designated as Series A Junior Participating Preferred Stock:

RESOLVED, that pursuant to the authority vested in the Board of Directors of the Corporation in accordance with the provisions of the Delaware General Corporation Law and the Certificate of Incorporation, a series of Preferred Stock of the Corporation be and it hereby is created, and that the designation and amount thereof and the powers, preferences and relative, participating, optional and other special rights of the shares of such series, and the qualifications, limitations or restrictions thereof are as follows:

Section 1. Designation and Amount. The shares of such series shall be designated as “Series A Junior Participating Preferred Stock” (the “Series A Preferred Stock”) and the number of shares constituting the Series A Preferred Stock shall be 100,000. Such number of shares may be increased or decreased by resolution of the Board of Directors; provided, that no decrease shall reduce the number of shares of Series A Preferred Stock to a number less than the number of shares then outstanding plus the number of shares reserved for issuance upon the exercise of outstanding options, rights or warrants or upon the conversion of any outstanding securities issued by the Company convertible into Series A Preferred Stock.

Section 2. Dividends and Distributions.

(A) Subject to the rights of the holders of any shares of any series of Preferred Stock of the Company (the “Preferred Stock”) (or any similar stock) ranking prior and superior to the Series A Preferred Stock with respect to dividends, the holders of shares of Series A Preferred Stock, in preference to the holders of Common Stock, par value $0.01 per share, of the Company (the “Common Stock”) and of any other stock of the Company ranking junior to the Series A Preferred Stock, shall be entitled to receive, when, as and if declared by the Board of Directors

out of funds legally available for the purpose, quarterly dividends payable in cash on the last day of January, April, July, and October in each year (each such date being referred to herein as a “Dividend Payment Date”), commencing on the first Dividend Payment Date after the first issuance of a share or fraction of a share of Series A Preferred Stock, in an amount per share (rounded to the nearest cent) equal to the greater of (a) $1.00 and (b) subject to the provision for adjustment hereinafter set forth, 1,000 times the aggregate per share amount of all cash dividends, and 1,000 times the aggregate per share amount (payable in kind) of all non-cash dividends or other distributions other than a dividend payable in shares of Common Stock, declared on the Common Stock since the immediately preceding Dividend Payment Date or, with respect to the first Dividend Payment Date, since the first issuance of any share or fraction of a share of Series A Preferred Stock. If the Company shall at any time after January 24, 2013 (the “Rights Declaration Date”) declare or pay any dividend on the Common Stock payable in shares of Common Stock, or effect a subdivision or combination or consolidation of the outstanding shares of Common Stock (by reclassification or otherwise than by payment of a dividend in shares of Common Stock) into a greater or lesser number of shares of Common Stock, then in each such case the amount to which holders of shares of Series A Preferred Stock were entitled immediately prior to such event under clause (b) of the preceding sentence shall be adjusted by multiplying such amount by a fraction, the numerator of which is the number of shares of Common Stock outstanding immediately after such event and the denominator of which is the number of shares of Common Stock that were outstanding immediately prior to such event.

(B) The Company shall declare a dividend or distribution on the Series A Preferred Stock as provided in paragraph Section 2(A) immediately after it declares a dividend or distribution on the Common Stock (other than a dividend payable in shares of Common Stock); provided that, in the event no dividend or distribution shall have been declared on the Common Stock during the period between any Dividend Payment Date and the next subsequent Dividend Payment Date, a dividend of $1.00 per share on the Series A Preferred Stock shall nevertheless be payable, when, as and if declared, on such subsequent Dividend Payment Date.

(C) Dividends shall begin to accrue and be cumulative, whether or not earned or declared, on outstanding shares of Series A Preferred Stock from the Dividend Payment Date next preceding the date of issue of such shares, unless the date of issue of such shares is prior to the record date for the first Dividend Payment Date, in which case dividends on such shares shall begin to accrue from the date of issue of such shares, or unless the date of issue is a Dividend Payment Date or is a date after the record date for the determination of holders of shares of Series A Preferred Stock entitled to receive a quarterly dividend and before such Dividend Payment Date, in either of which events such dividends shall begin to accrue and be cumulative from such Dividend Payment Date. Accrued but unpaid dividends shall not bear interest. Dividends paid on the shares of Series A Preferred Stock in an amount less than the total amount of such dividends at the time accrued and payable on such shares shall be allocated pro rata on a share-by-share basis among all such shares at the time outstanding. The Board of Directors may fix a record date for the determination of holders of shares of Series A Preferred Stock entitled to receive payment of a dividend or distribution declared thereon, which record date shall be not more than 60 days prior to the date fixed for the payment thereof.

2

Section 3. Voting Rights. The holders of shares of Series A Preferred Stock shall have the following voting rights:

(A) Subject to the provision for adjustment hereinafter set forth and except as otherwise provided in the Amended and Restated Certificate of Incorporation or required by law, each share of Series A Preferred Stock shall entitle the holder thereof to 1,000 votes on all matters upon which the holders of the Common Stock of the Company are entitled to vote. If the Company shall at any time after the Rights Declaration Date declare or pay any dividend on the Common Stock payable in shares of Common Stock, or effect a subdivision or combination or consolidation of the outstanding shares of Common Stock (by reclassification or otherwise than by payment of a dividend in shares of Common Stock) into a greater or lesser number of shares of Common Stock, then in each such case the number of votes per share to which holders of shares of Series A Preferred Stock were entitled immediately prior to such event shall be adjusted by multiplying such number by a fraction, the numerator of which is the number of shares of Common Stock outstanding immediately after such event and the denominator of which is the number of shares of Common Stock that were outstanding immediately prior to such event.

(B) Except as otherwise provided herein, in the Amended and Restated Certificate of Incorporation or in any other Certificate of Designations creating a series of Preferred Stock or any similar stock, and except as otherwise required by law, the holders of shares of Series A Preferred Stock and the holders of shares of Common Stock and any other capital stock of the Company having general voting rights shall vote together as one class on all matters submitted to a vote of stockholders of the Company.

(C) (i) If at any time dividends on any Series A Junior Participating Preferred Stock shall be in arrears in an amount equal to six (6) quarterly dividends thereon, the occurrence of such contingency shall mark the beginning of a period (herein called a “default period”) which shall extend until such time when all accrued and unpaid dividends for all previous quarterly dividend periods and for the current quarterly dividend period on all shares of Series A Junior Participating Preferred Stock then outstanding shall have been declared and paid or set apart for payment. During each default period, all holders of Preferred Stock (including holders of the Series A Junior Participating Preferred Stock) with dividends in arrears in an amount equal to six (6) quarterly dividends thereon, voting as a class, irrespective of series, shall have the right to elect two (2) Directors.

(ii) During any default period, such voting right of the holders of Series A Junior Participating Preferred Stock may be exercised initially at a special meeting called pursuant to this Section 3(c)(ii) or at any annual meeting of stockholders, and thereafter at annual meetings of stockholders, provided that such voting right shall not be exercised unless the holders of ten percent (10%) in number of shares of Preferred Stock outstanding shall be present in person or by proxy. The absence of a quorum of the holders of Common Stock shall not affect the exercise by the holders of Preferred Stock of such voting right. At any meeting at which the holders of Preferred Stock shall exercise such voting right initially during an existing default period, they shall have the

3

right, voting as a class, to elect Directors to fill such vacancies, if any, in the Board of Directors as may then exist up to two (2) Directors or, if such right is exercised at an annual meeting, to elect two (2) Directors from the class of Directors being elected at such annual meeting. If the number which may be so elected at any special meeting does not amount to the required number, the holders of the Preferred Stock shall have the right to make such increase in the number of Directors in the class elected at the most recent annual meeting of stockholders as shall be necessary to permit the election by them of the required number. After the holders of the Preferred Stock shall have exercised their right to elect Directors in any default period and during the continuance of such period, the number of Directors shall not be increased or decreased except by vote of the holders of Preferred Stock as herein provided or pursuant to the rights of any equity securities ranking senior to or pari passu with the Series A Junior Participating Preferred Stock.

(iii) Unless the holders of Preferred Stock shall, during an existing default period, have previously exercised their right to elect Directors, the Board of Directors may order, or any stockholder or stockholders owning in the aggregate not less than ten percent (10%) of the total number of shares of Preferred Stock outstanding, irrespective of series, may request, the calling of a special meeting of the holders of Preferred Stock, which meeting shall thereupon be called by the President, a Vice-President or the Secretary of the Corporation. Notice of such meeting and of any annual meeting at which holders of Preferred Stock are entitled to vote pursuant to this Section 3(c)(iii) shall be given to each holder of record of Preferred Stock by mailing a copy of such notice to such holder at such holder’s last address as the same appears on the books of the Company. Such meeting shall be called for a time not earlier than twenty (20) days and not later than sixty (60) days after such order or request, or in default of the calling of such meeting within sixty (60) days after such order or request, such meeting may be called on similar notice by any stockholder or stockholders owning in the aggregate not less than ten percent (10%) of the total number of shares of Preferred Stock outstanding. Notwithstanding the provisions of this Paragraph (c)(iii), no such special meeting shall be called during the period within sixty (60) days immediately preceding the date fixed for the next annual meeting of the stockholders.

(iv) In any default period, the holders of Common Stock, and other classes of stock of the Company if applicable, shall continue to be entitled to elect the whole number of Directors until the holders of Preferred Stock shall have exercised their right to elect two (2) Directors voting as a class, after the exercise of which right (x) the Directors so elected by the holders of Preferred Stock shall continue in office until their successors shall have been elected by such holders or until the expiration of the default period, and (y) any vacancy in the Board of Directors may (except as provided in Section 3(C)(ii)) be filled by vote of a majority of the remaining Directors theretofore elected by the holders of the class of stock which elected the Director whose office shall have become vacant. References in this Section (C) to Directors elected by the holders of a particular class of stock shall include Directors elected by such Directors to fill vacancies as provided in clause (y) of the foregoing sentence.

4

(v) Immediately upon the expiration of a default period, (x) the right of the holders of Preferred Stock as a class to elect Directors shall cease, (y) the term of any Directors elected by the holders of Preferred Stock as a class shall terminate, and (z) the number of Directors shall be such number as may be provided for in the certificate of incorporation or by-laws of the Company irrespective of any increase made pursuant to the provisions of Section 3(C)(ii) (such number being subject, however, to change thereafter in any manner provided by law or in the certificate of incorporation or by-laws of the Corporation). Any vacancies in the Board of Directors effected by the provisions of clauses (y) and (z) in the preceding sentence may be filled by a majority of the remaining Directors.

(D) Except as set forth herein, or as otherwise provided by law, holders of Series A Preferred Stock shall have no special voting rights and their consent shall not be required (except to the extent they are entitled to vote with holders of Common Stock as set forth herein) for taking any corporate action.

Section 4. Certain Restrictions.

(A) Whenever quarterly dividends or other dividends or distributions payable on the Series A Preferred Stock as provided in Section 2 are in arrears, thereafter and until all accrued and unpaid dividends and distributions, whether or not earned or declared, on shares of Series A Preferred Stock outstanding shall have been paid in full, the Company shall not:

(i) declare or pay dividends, or make any other distributions, on any shares of stock ranking junior (as to dividends) to the Series A Preferred Stock;

(ii) declare or pay dividends, or make any other distributions, on any shares of stock ranking on a parity (as to dividends) with the Series A Preferred Stock, except dividends paid ratably on the Series A Preferred Stock and all such parity stock on which dividends are payable or in arrears in proportion to the total amounts to which the holders of all such shares are then entitled;

(iii) redeem or purchase or otherwise acquire for consideration shares of any stock ranking junior (either as to dividends or upon liquidation, dissolution or winding up) to the Series A Preferred Stock, provided that the Company may at any time redeem, purchase or otherwise acquire shares of any such junior stock in exchange for shares of any stock of the Company ranking junior (as to dividends and upon dissolution, liquidation or winding up) to the Series A Preferred Stock or rights, warrants or options to acquire such junior stock;

(iv) redeem or purchase or otherwise acquire for consideration shares of any stock ranking on a parity (either as to dividends or upon liquidation, dissolution or winding up) with the Series A Junior Participating Preferred Stock, provided, that the Company may at any time redeem, purchase or otherwise acquire shares of any such parity stock in exchange for shares of any stock of the Company ranking junior (either as to dividends or upon dissolution, liquidation or winding up) to the Series A Junior Participating Preferred Stock; or

5

(v) redeem or purchase or otherwise acquire for consideration any shares of Series A Preferred Stock, or any shares of stock ranking on a parity (either as to dividends or upon liquidation, dissolution or winding up) with the Series A Preferred Stock, except in accordance with a purchase offer made in writing or by publication (as determined by the Board of Directors) to all holders of such shares upon such terms as the Board of Directors, after consideration of the respective annual dividend rates and other relative rights and preferences of the respective series and classes, shall determine in good faith will result in fair and equitable treatment among the respective series or classes.

(B) The Company shall not permit any subsidiary of the Company to purchase or otherwise acquire for consideration any shares of stock of the Company unless the Company could, under Section 4(A), purchase or otherwise acquire such shares at such time and in such manner.

Section 5. Reacquired Shares. Any shares of Series A Preferred Stock purchased or otherwise acquired by the Company in any manner whatsoever shall be retired and cancelled promptly after the acquisition thereof. All such shares shall upon their retirement become authorized but unissued shares of Preferred Stock and may be reissued as part of a new series of Preferred Stock to be created by resolution or resolutions of the Board of Directors, subject to any conditions and restrictions on issuance set forth herein.

Section 6. Liquidation, Dissolution or Winding Up.

(a) Upon any liquidation (voluntary or otherwise), dissolution or winding up of the Company, no distribution shall be made to the holders of shares of stock ranking junior (either as to dividends or upon liquidation, dissolution or winding up) to the Series A Junior Participating Preferred Stock unless, prior thereto, the holders of shares of Series A Junior Participating Preferred Stock shall have received an amount equal to $100 per share of Series A Junior Participating Preferred Stock, plus an amount equal to accrued and unpaid dividends and distributions thereon, whether or not declared, to the date of such payment (the “Series A Liquidation Preference”). Following the payment of the full amount of the Series A Liquidation Preference, no additional distributions shall be made to the holders of shares of Series A Junior Participating Preferred Stock unless, prior thereto, the holders of shares of Common Stock shall have received an amount per share (the “Common Adjustment”) equal to the quotient obtained by dividing (i) the Series A Liquidation Preference by (ii) 1,000 (as appropriately adjusted as set forth in subparagraph (c) below to reflect such events as stock splits, stock dividends and recapitalizations with respect to the Common Stock) (such number in clause (ii), the “Adjustment Number”). Following the payment of the full amount of the Series A Liquidation Preference and the Common Adjustment in respect of all outstanding shares of Series A Junior Participating Preferred Stock and Common Stock, respectively, holders of Series A Junior Participating Preferred Stock and holders of Common Stock shall receive their ratable and proportionate share of the remaining assets to be distributed in the ratio of the Adjustment Number (with respect to such Preferred Stock) to 1 (with respect to such Common Stock) on a per share basis.

6

(b) If, however, there are not sufficient assets available to permit payment in full of the Series A Liquidation Preference and the liquidation preferences of all other series of Preferred Stock, if any, which rank on a parity (either as to dividends or upon liquidation, dissolution or winding up) with the Series A Junior Participating Preferred Stock, then such remaining assets shall be distributed ratably to the holders of such parity shares in proportion to their respective liquidation preferences. In the event, however, that there are not sufficient assets available to permit payment in full of the Common Adjustment, then such remaining assets shall be distributed ratably to the holders of Common Stock.

(c) If the Company shall at any time after the Rights Declaration Date (i) declare any dividend on Common Stock payable in shares of Common Stock, (ii) subdivide the outstanding Common Stock, or (iii) combine the outstanding Common Stock into a smaller number of shares, then in each such case the Adjustment Number in effect immediately prior to such event shall be adjusted by multiplying such Adjustment Number by a fraction the numerator of which is the number of shares of Common Stock outstanding immediately after such event and the denominator of which is the number of shares of Common Stock that were outstanding immediately prior to such event.

Section 7. Consolidation, Merger, etc. If the Company shall enter into any consolidation, merger, combination or other transaction in which the shares of Common Stock are converted into, exchanged for or changed into other stock or securities, cash and/or any other property, then in any such case each share of Series A Preferred Stock shall at the same time be similarly converted into, exchanged for or changed into an amount per share (subject to the provision for adjustment hereinafter set forth) equal to 1,000 times the aggregate amount of stock, securities, cash and/or any other property (payable in kind), as the case may be, into which or for which each share of Common Stock is converted, exchanged or converted. If the Company shall at any time after the Rights Declaration Date declares or pays any dividend on the Common Stock payable in shares of Common Stock, or effect a subdivision or combination or consolidation of the outstanding shares of Common Stock (by reclassification or otherwise than by payment of a dividend in shares of Common Stock) into a greater or lesser number of shares of Common Stock, then in each such case the amount set forth in the preceding sentence with respect to the conversion, exchange or change of shares of Series A Preferred Stock shall be adjusted by multiplying such amount by a fraction, the numerator of which is the number of shares of Common Stock outstanding immediately after such event and the denominator of which is the number of shares of Common Stock that were outstanding immediately prior to such event.

Section 8. No Redemption. The shares of Series A Preferred Stock shall not be redeemable from any holder.

Section 9. Rank. The Series A Preferred Stock shall rank, with respect to the payment of dividends and the distribution of assets upon liquidation, dissolution or winding up of the Company, junior to all other series of Preferred Stock and senior to the Common Stock.

Section 10. Amendment. If any proposed amendment to the Amended and Restated Certificate of Incorporation (including this Certificate of Designations) would alter, change or repeal any of the preferences, powers or special rights given to the Series A Preferred Stock so as to affect the Series A Preferred Stock adversely, then the holders of the Series A Preferred Stock

7

shall be entitled to vote separately as a class upon such amendment, and the affirmative vote of a majority of the outstanding shares of the Series A Preferred Stock, voting separately as a class, shall be necessary for the adoption thereof, in addition to such other vote as may be required by the General Corporation Law of the State of Delaware.

Section 11. Fractional Shares. Series A Preferred Stock may be issued in fractions of a share that shall entitle the holder, in proportion to such holder’s fractional shares, to exercise voting rights, receive dividends, participate in distributions and to have the benefit of all other rights of holders of Series A Preferred Stock.

8

IN WITNESS WHEREOF, this Certificate of Designations is executed on behalf of the Company by its President and attested by its Secretary this 28th day of January, 2013.

Attest:

Signature Page to Certificate of Designation