(dissenting). I respectfully dissent from the majority opinion. The board has promulgated a regulation excessively *29broad in scope, purporting to require an electrician’s license for “fire alarm and all signal work requiring the use of wire for transmission,” and has exceeded its authority in doing so. The installation of fire and burglar alarm systems, insofar as it involves installation of wires or other apparatus used only for the purpose of transmitting low voltage, limited current electrical signals, does not fall within the definition of wiring and equipment for “carrying or using electricity for light, heat and power purposes,” as that phrase appears in G. L. c. 141, § 1. Such work is thus beyond the scope of the board’s regulatory authority.
Since G. L. c. 141, § 1, is not permissive but mandatory, the majority opinion, interpreting that section to authorize the challenged regulation, appears to have the effect of requiring a licensed electrician to install any appliance, equipment, or wiring, which simply plugs into a standard household outlet. Even the installation of wires connecting intercom, paging, or public address systems would seem to require a licensed electrician, under the reasoning of the majority.1 The Legislature could not have intended a result so contrary to common sense in adopting G. L. c. 141, §§ 1-2. Moreover, quite aside from driving some of the plaintiffs out of business, the result which the majority reaches will impose a significant cost without corresponding benefit upon the public.
The use of electricity for the purpose or intended result of transmitting a limited current electrical signal is a use separate and distinct from the use of electricity for the purpose or intended result of producing heat, light, or power. Other statutory provisions in the Commonwealth recognize the distinct nature of those uses.2 The board’s contrary contention that the *30transmission of signals over wire constitutes the “use of electricity for heat, light and power purposes” is belied by the board’s own regulation: the board has deemed it necessary to add the words “fire alarm and all signal work requiring the use of wire for transmission” to the statutory language in order to bring the plaintiffs’ work within the ambit of the regulation. Plainly, the board did not consider the statutory language alone sufficient to establish the requirement of an electrician’s license for “fire alarm and all signal work.”
In promulgating a regulation with such broad and inseverable language, the board has swept in matters both inside and outside of its scope of authority. I would not dispute the board’s authority to regulate certain aspects of the plaintiffs’ work (e.g., hard wiring [direct connection] with a power source). Indeed, the plaintiffs themselves do not appear to contest the board’s authority to require an electrician’s license for hard wiring since, by their own stipulation, the plaintiffs always have a licensed electrician do any necessary hard wiring. However, the board does not have authority under G. L. c. 141, §§ 1 and 2, to require an electrician’s license for the installation of low voltage, limited current signaling systems, not unlike telephone *31or intercom systems,3 which connect with a power source by means of a plug placed in a preexisting household outlet. Thus the portion of the regulation at issue purporting to regulate such installations is on its face beyond the scope of the board’s authority and was properly declared invalid by the Superior Court judge.
I cannot agree with the conclusion of the majority that the challenged regulation, despite its sweeping scope, is valid because “reasonably related” to the purpose of the enabling legislation, protecting public health and safety. More is required to justify raising the concern of public health and safety than the danger of a 12-volt shock4 or the danger posed by the insertion of a plug in an electrical socket. I see no evidence that, by adopting c. 141, the Legislature intended to invest the board with authority to regulate all electrical work which could present any risk to public health and safety, no matter how inconsequential the risk and no matter how remote the likelihood of realizing that risk. In fact there is evidence to the contrary. The Legislature has twice declined to adopt proposed amendments to c. 141 expanding the board’s jurisdiction. See note 5, infra.
I am not persuaded by the majority’s discussion of the legislative history of enactments other than the one before us. Cf. Commonwealth v. Brown, 391 Mass. 157, 162 (1984) (wherein the court stated, “We do not agree that the intent of the Legislature in 1915, in enacting G. L. c. 43, § 28 [governing bidding on public contracts], is revealed by statutes enacted many years later when the range of legislative concern may well have expanded to include . . . [matters] that were not the concern of the earlier Legislature”). That discussion does not explain why signaling, certainly a use of electricity well known in 1915 and probably the first common use of electricity, was omitted from the phrase describing the type of wiring and *32equipment for which the board was authorized to issue licenses under G. L. c. 141, §§ 1 and 2. Heat, light, and power may indeed be “but varied manifestations of the same thing”: different employments of identical electrical current, presenting identical risks. However, low voltage, limited current signaling is not.
Nor am I persuaded that the interpretation which a different agency, the Board of Fire Prevention Regulations, has attached to similar language appearing in a different statute, G. L. c. 143, § 3L, supports the majority’s construction of G. L. c. 141, § 1. In the first place, the Board of Fire Prevention Regulations has not promulgated regulations so broad in scope as the one presently before the court. Its regulations apply to “. . . outside wiring for fire alarm and burglar alarms and similar central station systems ...” (emphasis added). 527 Code Mass. Regs. § 12.00, art. 800-1 (1981). However the words “outside wiring” might be defined, they are plainly less inclusive than the words “fire alarm and all signal work requiring the use of wire for transmission” appearing in the regulation at issue. None of the regulations included in 527 Code Mass. Regs. § 12.00, art. 800 (1981), would apply to the typical burglar alarm system described in the parties’ stipulation. Secondly, to the extent regulations promulgated by the Board of Fire Prevention Regulations purport to regulate the installation of wiring and equipment used only for the purpose of transmitting low voltage signals, those regulations do not appear to be authorized by G. L. c. 143, § 3L.5
*33Moreover, it is clear that much of the plaintiffs’ work could not pose any significant threat to public health or safety. The parties’ stipulation provides that “[a]ll modem burglar alarm systems and approximately fifty percent of all fire alarm systems are connected to a power supply by means of a plug-in transformer.” Thus, the bulk of the systems installed by the plaintiffs simply plug into an existing standard household outlet and, due to the transformer, are powered by a low voltage, limited current of electricity. The danger posed is no greater than that posed by a telephone, and probably less than that posed by any ordinary household appliance which plugs into a household outlet. Cf. 527 Code Mass. Regs. § 12.00, art. 725-40 (for certain “low energy” circuits, “conductor insulation is not specified in . . . detail as reliance is placed on . . . power supplies which limit voltage and current to safe values”). As the trial judge noted, “[T]he use of very little current does make a difference.” In stating that “there was testimony on a point we think obvious: that the improper installation of wire conduits could cause fire and electrical shock,” the majority fails to distinguish between very different types of wiring: ordinary wiring, carrying a full current of electricity, connecting directly to a power source, as opposed to low voltage wiring carrying a low voltage, limited current of electricity connecting to a power source by means of a transformer plugged into a preexisting standard household outlet. The majority also relies on the heavily contradicted testimony of a single witness, *34who admitted having no recent experience in alarm installations, regarding a matter on which the trial judge made no findings of fact.6
In reaching the conclusion that the portion of the regulation in question is beyond the scope of the board’s statutory authority, I am not unmindful of the presumption of validity to which the regulation is entitled, see, e.g., Consolidated Cigar Corp. v. Department of Pub. Health, 372 Mass. 844, 855 (1977); White Dove, Inc. v. Director of the Div. of Marine Fisheries, 380 Mass. 471, 477 (1980), and the degree of deference to which the board’s interpretation of the statute it is charged with enforcing is entitled, see, e.g., Grocery Manufacturers of America, Inc. v. Department of Public Health, 379 Mass. 70, 75, 85 (1979).7 However, these principles are principles of *35deference, not abdication. See Nickerson v. Ribicoff, 206 F. Supp. 232, 234 (1962). Cf. Finkelstein v. Board of Registration in Optometry, 370 Mass. 476, 478 (1976); Board of Educ. v. School Committee of Amesbury, 16 Mass. App. Ct. 508, 514 (1983). “The construction of the statute is a matter of law and ... the courts cannot be bound by an erroneous statutory construction by an administrative body.” McDonough v. Contributory Retirement Appeal Board, 15 Mass. App. Ct. 14, 15 (1982), citing Russo v. Director of the Div. of Employment Security, 377 Mass. 645, 649 (1979); Johnson v. Martignetti, 374 Mass. 787, 790 (1978). See Treasurer and Receiver General v. John Hancock Mut. Life Ins. Co., 388 Mass. 410, 423 n.25 (1983). Judicial deference to an agency’s attempt to extend its authority beyond statutory confines is especially inappropriate when, as here, such an extension would be tantamount to granting a legal monopoly to the trade group which the agency not only regulates but from which its members are *36drawn.8 See Gellhom, Abuse of Occupational Licensing, 44 U. Chi. L. Rev. 6 (1976).
In my view, the court should not defer to the board’s broad construction of the phrase “heat, light and power purposes,” as it appears in G. L. c. 141, § 1, to include all uses of electricity, because that construction renders the phrase superfluous. Cf. Morello v. Boston Rent Control Bd., 14 Mass. App. Ct. 27, 32 n.4 (1982). “None of the words of a statute is to be disregarded, for they are the main source for the ascertainment of the legislative purpose.” Treasurer and Receiver General v. John Hancock Mut. Life Ins. Co., 388 Mass. at 422. United States Jaycees v. Mass. Commn. Against Discrimination, 391 Mass. 594, 602 (1984). See Commonwealth v. Brown, 391 Mass. at 162. The board’s construction of the phrase in question has the effect of removing the phrase from the statute; with the phrase removed, the statute would require the licensing of persons, firms and corporations which “enter into, engage in, or work at the business of installing wires, conduits, apparatus, fixtures or other appliances for carrying or using electricity.” This truncated version of the statute is not the version which the Legislature enacted. Compare G. L. c. 164, § 1(7), as amended through St. 1982, c. 120, § 3 (regulation of corporations “selling, or distributing and selling, electricity within the Commonwealth. . . ”). The task of amending a statute is solely the responsibility of the Legislature.9 Mellor v. Berman, 390 Mass. 275, 283 (1983).
*37In my view, the words “heat, light and power” must be read as words of qualification or limitation, from which the court must necessarily infer the existence and exclusion from c. 141 of other purposes for which electricity might be used. Such a reading is consistent with the principle that, as a penal statute, G. L. c. 141, § 1, must be construed strictly in determining the scope of its application, see Maria v. State Examrs. of Electricians, 365 Mass. 551, 554 (1974); Commonwealth v. Brown, supra at 159, and the principle that “a statutory expression of one thing is an implied exclusion of other things omitted from the statute.” County of Middlesex v. Newton, 13 Mass. App. Ct. 538, 542-543 (1982), and authorities therein cited. See Cawley v. Northern Waste Co., 239 Mass. 540, 542-544 (1921) (implicitly approving portion of city ordinance promulgated in discharge of city’s duty under St. 1890, c. 404, § 3 [see now G. L. c. 166, § 32], to provide for appointment or designation of an officer to “supervise . . . every wire within a building when such wire is designed to carry an electric light or power current,” providing that ordinance did not call for inspection of electric bell system); Rep. A.G. Pub. Doc. No. 12, at 22-23 (1948) (wires and apparatus for transmission of television signals are not installed or used for carrying or using “electricity for light, heat and power purposes” within the meaning of G. L. c. 141, § 7; nor do they carry “an electric light, heat or power current” within the meaning of G. L. c. 166, §§ 30-32). Cf. G. L. c. 166, § 30 (prescribing, among other things, insulation requirements for outdoor transmission wires, where wire is “designed to carry an electric light, heat or power current” and where “wire is other than a wire designed to carry an electric light, heat or power current”).
There is no rational way to sever any portion of the regulation’s language or otherwise whittle it down to preserve the *38board’s assertion of authority with respect to some aspects of alarm installation. Therefore, the question whether the board has the authority to regulate other nonsignaling or higher voltage aspects of the installation of alarm systems which could pose a threat to public safety, such as “hard wiring” or the automatic control of ventilation systems, is not presently before the court. Since the portion of the regulation at issue is on its face beyond the scope of the board’s authority under § 1, there is no issue with respect to the adequacy of the plaintiffs’ development of the record below which could preclude entry of judgment declaring that portion of the regulation invalid. See G. L. c. 231A, § 2; G. L. c. 30A, § 7. I would affirm the judgment of the Superior Court.
Because I would uphold the judgment of the Superior Court declaring the portion of the regulation at issue invalid as beyond the board’s authority under G.L. c. 141, § 1, I would not reach the question whether the plaintiffs’ work falls within the exemption for the transmission of intelligence by electricity contained within G. L. c. 141, § 7. Were I to reach that question, I would not necessarily reach the result which the majority reaches.
According to the testimony of the board’s only witness, burglar and fire alarm systems, doctors’ register systems, nurses’ call systems, paging systems, intercom systems, and telephones all fall into the same category of electrical work.
See G. L. c. 166, § 21, as appearing in St. 1951, c. 476, § 1 (regulating companies “incorporated for the transmission of intelligence by electricity or by telephone, whether by electricity or otherwise, or for the transmission of television signals, whether by electricity or otherwise, or for the transmis*30sion of electricity for lighting, heating or power, or for the construction and operation of a street railway or an electric railroad . . .”); G. L. c. 166, § 22A, as appearing in St. 1969, c. 884, § 1 (defining regulated “poles and overhead wires” to include those “used or useful in the transmission of intelligence by electricity or otherwise, or for the transmission of television signals, whether by electricity or otherwise, or for the transmission of electricity for lighting, heating or power, or for the construction or operation of a street railway or an electric railroad . . .”). See also 527 Code Mass. Regs. § 12.00, art. 725-1 (1981) (a regulation promulgated by the Board of Fire Prevention Regulations, stating that certain “signaling] ] and power limited circuits ... are characterized by usage and electrical power limitations which differentiate them from light and power circuits . . .”). Statutory provisions enacted by the Legislatures of other States have also recognized the distinct nature of those uses. See N.Y. Gen. City Law § 20 (McKinney 1968) (defining “master electrician” as person or entity who or which installs, alters or repairs “any electric wires or wiring apparatus, fixtures and other appliances used or to be used for the transmission of electricity for light, heat or power, or signaling system where more than fifty volts is required for its operation”).
The board’s only witness testified that burglar and fire alarm systems are similar to telephone systems, both using low voltage electricity.
Such a shock would be at most “slight” even according to the testimony of the board’s only witness.
This construction of G. L. c. 143, § 3L, would not necessarily cast doubt upon the authority of the Board of Fire Prevention Regulations (established under G. L. c. 22, § 14) to promulgate rules relating to the fire safety of electrical wiring and equipment applicable to the work done by the plaintiffs. See 527 Code Mass. Regs. § 12.00, art. 800 (1981). The Board of Fire Prevention Regulations is charged with the duty of promulgating a “comprehensive fire safety code.” G. L. c. 22, § 14, as appearing in St. 1980, c. 462, § 1. G. L. c. 148, § 28, as appearing in St. 1982, c. 520. In carrying out that duty, that board is required to promulgate regulations to, among other things, “prevent or remedy any condition in or about any building, structure or other premises . . . which may tend to become a fire hazard or to cause a fire.” G. L. c. 148, § 28. Thus the Legislature has vested the Board of Fire Prevention Regulations with broad authority to *33determine the appropriate focus or subject matter of those regulations. Compare earlier versions of G. L. c. 148, § 28 (St. 1945, c. 710; St. 1980, c. 462, § 2), which allowed the board substantially less discretion. (It is noteworthy that the discretion of the of State Examiners of Electricians has not been similarly expanded.) Therefore, notwithstanding the presence of the phrase here at issue in G. L. c. 143, § 3L (expressly requiring the Board of Fire Prevention Regulations to promulgate rules relating to the fire safety of electrical wiring and equipment used for “light, heat, and power purposes”), the court would not be constrained to conclude that regulations applicable to the plaintiffs in the instant case promulgated by the Board of Fire Prevention Regulations are beyond that board’s scope of authority. See Grocery Manufacturers of America, Inc. v. Department of Pub. Health, 379 Mass. 70, 76 (1979) (“[sjpecific statutory authority to act in a particular respect does not bar consistent action under general statutory authority”).
It should also be noted that history indicates that the majority’s public safety concern is without foundation. The parties’ stipulation of agreed facts contains the statements that “no claims have ever been filed against any of the Plaintiffs claiming any personal injuries or death or property damage as a result of their assembly or installation of burglar and/or fire and/or smoke alarm equipment in Massachusetts,” and that “the Defendant Board has no records of complaints of personal injury or death or property damage attributable to faulty or defective assembly or installation of burglar and/or fire and/or smoke alarm equipment in Massachusetts.” The plaintiffs have all been in the alarm installation business for substantial periods of time, ranging from twenty-three to one hundred six years.
The degree of deference to which an agency’s interpretation of a statute is entitled is itself a question of legislative intent. Ciampa v. Secretary of Health and Human Services, 687 F.2d 518, 526 (1st Cir. 1982). See Massachusetts Organization of State Engineers & Scientists v. Labor Relations Commn., 389 Mass. 920, 924 (1983). Where the Legislature has granted broad agency authority to deal with an entire area of activity, the agency’s interpretation of its statute is “especially significant” and entitled to great weight. Massachusetts Organization of State Engineers & Scientists v. Labor Relations Commn., supra. “Where no such broad statutory grant exists, closer scrutiny of the authority of the agency is required and has been applied.” Grocery Manufacturers of America, Inc. v. Department of Pub. Health, 379 Mass. 70, 75 (1979), and cases therein cited. I do not consider the board to be possessed of a broad statutory grant; thus I would give closer scrutiny to the board’s construction of the statute determining the scope of its authority. Cf. Grocery Manufacturers of America, Inc. v. Department of Pub. Health, supra at 75-77; Morello v. Boston Rent Control Bd., 14 Mass. App. Ct. 27, 32-33 (1982); Massachusetts Retired Police & Firefighters Assn. v. Retirement Bd. of Belmont, 15 Mass. App. Ct. 212, 217 *35n.7 (1983). Compare Warner Cable of Mass., Inc. v. Community Antenna Television Commn., 372 Mass. 495 (1977); Rock v. Massachusetts Commn. Against Discrimination, 384 Mass. 198, 206-208 (1981). I would further note that this is not a case involving either consistent or contemporaneous agency interpretation of a statute which would entitle the agency interpretation to greater weight. See Cleary v. Cardullo’s, Inc., 347 Mass. 337, 343 (1964); Casa Loma, Inc. v. Alcoholic Beverages Control Commn., 377 Mass. 231, 235 (1979). Moreover, although administrative power granted by the Legislature cannot lapse through an agency’s failure to exercise it, the hiatus of nearly sixty years between the board’s assumption of its duties and its first assertion of jurisdiction over the plaintiffs is suggestive of a lack of authority. “[Jjust as established practice may shed light on the extent of power conveyed by general statutory language, so the want of assertion of power by those who presumably would be alert to exercise it, is equally significant in determining whether such power was actually conferred.” Federal Trade Commn. v. Bunte Bros., 312 U.S. 349, 352 (1941). See 2A Sands, Sutherland Statutory Construction, § 49.05, at 239 (4th ed. 1973). In this regard, it is noteworthy that, according to the board’s only witness, the average alarm system has become far less dangerous in the last ten or twenty years due to the advent of 12-volt and 24-volt systems. Thus, the board cannot argue that its recent assertion of authority over alarm installations is in response to increased danger in alarm systems. Counsel for the board at trial conceded that “the technology, and indeed some of the plaintiff organizations, predate the 1915 date of the statute.”
Indeed, the Electrical Contractors Association of Greater Boston had an interest in the board’s expansion of authority significant enough to prompt, it to file an amicus brief in this case. See n.4 to the majority opinion.
It should be noted that on at least two occasions, the Legislature has declined to amend the statute specifically to include within the board’s jurisdiction the installation of wires and equipment using electricity for purposes other than heat, light, or power. See 1975 House Doc. No. 145 (allowing board to regulate installation of wires and equipment “for carrying or using electricity for light, heat or power purposes, or any other purposes . . .” [emphasis added]); 1973 House Doc. No. 4143 (allowing board to regulate installation of wires and equipment “for carrying or using electricity for light, heat, power, burglar alarm, fire alarm, sprinkler alarm, x-ray equipment, communication systems and signal systems . . .”). Although the *37failure of those two bills to pass might be interpreted as a legislative judgment that such amendments were unnecessary because the statute already conferred the broader jurisdiction on the board, it is far more likely that the failure represents a legislative decision not to expand the board’s jurisdiction. See 2A Sands, Sutherland Statutory Construction § 48.18, at 224 (4th ed. 1973), citing Rea v. Aldermen of Everett, 217 Mass. 427 (1914). The 1975 bill was sponsored by the board.