Dissenting Opinion by
Judge Blatt:I respectfully dissent.
“When interpreting a contract the intention of the parties must be determined, and in ascertaining that intention effect must be given to all the provisions of the contract. ... In a written contract the intent of the parties is the writing itself and when the words are clear and unambiguous the intent is to be determined only from the express language of the agreement.” *436Robert F. Felte, Inc. v. White, 451 Pa. 137, 143, 302 A. 2d 347, 351 (1973). The language of the contract here involved clearly indicates, in my opinion, that the intent of the parties thereto was that John McShain, Inc. (McShain) should not he responsible for installing the electrical wiring of the Detex Alarm System.
The only mention of the alarm system is under that section of the contract entitled “Finishing Hardware.” There is nothing in this section which concerns anything in addition to the hardware, and McShain did in fact furnish and install all of the finishing hardware for the alarm system. In addition, Section lA.l(c) (2) of McShain’s contract provides that it would not include electrical construction, which would be done under a separate contract.
Admittedly, of course, the General State Authority (GSA) failed to include the wiring for the alarm system in its contract with the electrical contractor, but this does not affect the fact that its contract with Mc-Shain on its face clearly indicates the intent of the parties to be that McShain would install the finishing hardware for the alarm system and that all electrical construction, including, presumably, the wiring for the alarm system, would be done by the electrical contractor. When the contract is clear and unambiguous on its face, as it is here, extrinsic circumstances such as the failure of the GSA to make any other provision for certain wiring should not be considered.
The majority puts great weight on Paragraph 17, Section III, of the General Conditions of Contract No. G.S.A. 1104-10.1, but that paragraph seems to me to be clearly intended to cover only minor or incidental changes in the specifications or drawings which could not have been foreseen when the contract was entered into and which are normally expected in any large construction job. It certainly could not have been intended to authorize the GSA to require a contract alteration, *437especially where, as here, such alteration would be totally inconsistent with the normal and accepted division of duties between a general contractor and an electrical contractor.
McShain should not be penalized for the obvious failure of the GSA to make specific provisions for the electrical wiring of the alarm system either in its contract with him or in its contract with the electrical contractor.