Opinion
SIMS, J.
In this indisputably shocking case we hold that a consumer, who was injured when a mechanical failure in an electric utility transformer sent 7,000 volts of electricity into her home, may state a cause of action against Pacific Gas and Electric Company (PG & E) for strict liability in tort.
[74]*74Factual and Procedural Background
A lightning storm struck the Meridian area of Sutter County on the afternoon of November 21, 1978. Several PG & E power transformers were struck and damaged by lightning, including two on plaintiffs’ property. Plaintiffs’ home lost its electricity.
Plaintiff Gail Pierce summoned PG & E, whose crew arrived at about 1:30 a.m. the morning of November 22. The PG & E crew, working in the rain, removed the lightning-damaged transformers from the pole and lifted their replacements into position. One of the replacements had previously been used at another location and had been removed and stored when it was no longer needed. There was no evidence that the transformer had malfunctioned in its previous location, but the PG & E crew did not test the transformer before connecting it to the powerline.
The PG & E crew made two of the three connections from the 12,000-volt powerline to the top of the transformers without incident, but, as a lineman attempted the third connection, the used transformer exploded in a ball of fire.
Gail observed a bit of smoke coming from the motor area of her freezer and saw a red glow in her storage shed. A fire had started in the shed. Upon closer examination Gail saw that the fire was coming from a propane gas pipe, which had ruptured.
A PG & E employee who was nearby extinguished the fire and told Gail that gas was still coming out of the pipe. He asked, “Where’s the shut off valve?” Gail replied that she would go shut it off.
As Gail grasped the propane gas tank’s shutoff valve she received a terrible shock. The shock tightened her hand around the valve and she could not let go. At some point, maybe 10 or 20 seconds later, Gail fell or slid onto the propane tank, and the force of the electricity blew her hand free of the valve. Gail tumbled away from the tank and down an embankment about six feet high. She was injured.
Plaintiffs’ expert witness testified that the transformer malfunction had energized their house wiring, designed for 120 and 240 volts, with approximately 7,000 volts. Postaccident investigation revealed poorly insulated wiring and a ground wire unlawfully connecting plaintiffs’ electrical system to the propane gas system.
Plaintiffs filed this action on August 28, 1979, alleging negligence and strict liability in tort for defective products. Plaintiffs’ second cause of ac-
[75]*75tion for products liability alleged that PG & E was “engaged in the business of designing, manufacturing, distributing, selling, leasing, renting, to the general public electrical equipment, including the particular equipment involved in this matter.” Plaintiffs’ complaint did not identify the electricity itself as a defective product. PG & E answered, and plaintiffs have never amended their complaint.
The case was tried before a jury, and after plaintiffs rested PG & E moved for a nonsuit on the issue of products liability. Plaintiffs responded with a motion for directed verdict. Plaintiffs’ motion was premised on theories of (1) strict products liability, (2) absolute liability for ultrahazardous activity, and (3) breach of implied warranty of fitness for particular purpose. The latter two theories were not contained in plaintiffs’ pleadings and were not advanced until the date of the motion (June 20, 1983), nearly four years after the case was originally filed.
After both sides rested the trial court denied plaintiffs’ motion for directed verdict and granted PG & E’s motion for nonsuit.
The case went to the jury on the negligence cause of action, and the jury found by special verdict that PG & E was not negligent. Judgment was entered for PG & E. Plaintiffs’ motions for judgment notwithstanding the verdict and new trial were denied, and plaintiffs filed a timely notice of appeal.
Discussion
I
We first consider the trial court’s entry of nonsuit on plaintiffs’ second cause of action for products liability.
“A motion for nonsuit allows a defendant to test the sufficiency of the plaintiff’s evidence before presenting his or her case. Because a successful nonsuit motion precludes submission of plaintiff’s case to the jury, courts grant motions for nonsuit only under very limited circumstances. (Campbell v. General Motors Corp. (1982) 32 Cal.3d 112, 117 [184 Cal.Rptr. 891, 649 P.2d 224].) A trial court must not grant a motion for nonsuit if the evidence presented by the plaintiff would support a jury verdict in the plaintiff’s favor. (Id. at pp. 117-118; Ewing v. Cloverleaf Bowl (1978) 20 Cal.3d 389, 395 [143 Cal.Rptr. 13, 572 P.2d 1155.)
“ ‘In determining whether plaintiff’s evidence is sufficient, the court may not weigh the evidence or consider the credibility of witnesses. Instead, the [76]*76evidence most favorable to plaintiff must be accepted as true and conflicting evidence must be disregarded. The court must give “to the plaintiff[’s] evidence all the value to which it is legally entitled, . . . indulging every legitimate inference which may be drawn from the evidence in plaintiff[’s] favor . . . (Campbell v. General Motors Corp., supra, 32 Cal.3d at p. 118, quoting Elmore v. American Motors Corp. (1969) 70 Cal.2d 578, 583 [75 Cal.Rptr. 652, 451 P.2d 84, 33 A.L.R.3d 406]; accord Ewing v. Cloverleaf Bowl, supra, 20 Cal.3d at p. 395; Estate of Lances (1932) 216 Cal. 397, 400 [14 P.2d 768].)
“In an appeal from a judgment of nonsuit, the reviewing court is guided by the same rule requiring evaluation of the evidence in the light most favorable to the plaintiff. ‘The judgment of the trial court cannot be sustained unless interpreting the evidence most favorably to plaintiff’s case and most strongly against the defendant and resolving all presumptions, inferences and doubts in favor of the plaintiff a judgment for the defendant is required as a matter of law.’ (Mason v. Peaslee (1959) 173 Cal.App.2d 587, 588 [343 P.2d 805]; accord Miller v. Los Angeles County Flood Control Dist. (1973) 8 Cal.3d 689, 699 [106 Cal.Rptr. 1, 505 P.2d 193]; Hughes v. Oreb (1951) 36 Cal.2d 854, 857 [228 P.2d 550].)” (Carson v. Facilities Development Co. (1984) 36 Cal.3d 830, 838-839 [206 Cal.Rptr. 136, 686 P.2d 656].)
Plaintiffs’ second cause of action was premised on the theory of strict liability in tort for defective products. Under this theory “A manufacturer is strictly liable in tort when an article he places on the market, knowing that it is to be used without inspection for defects, proves to have a defect that causes injury to a human being.” (Greenman v. Yuba Power Products, Inc. (1963) 59 Cal.2d 57, 62 [27 Cal.Rptr. 697, 377 P.2d 897, 13 A.L.R.3d 1049]; see Hasson v. Ford Motor Co. (1982) 32 Cal.3d 388, 406 [185 Cal.Rptr. 654, 650 P.2d 1171].) Undisputed evidence at trial established that the defective transformer was manufactured not by PG & E but by Federal Pacific Electric Company, and that PG & E never placed the transformer “on the market” or in the stream of commerce. PG & E was, in essence, a consumer rather than a manufacturer of the transformer, and cannot be held strictly liable in tort for the transformer’s defects per se. (Price v. Shell Oil Co. (1970) 2 Cal.3d 245, 258 [85 Cal.Rptr. 178, 466 P.2d 722].)
Evidence presented at trial also established, however, that PG & E’s electricity arrived at plaintiffs’ home at nearly 60 times its in[77]*77tended voltage,1 ultimately causing Gail to suffer bodily injury. Plaintiffs contend that household electricity must be considered a product for strict liability purposes, that their evidence was sufficient to support a verdict in their favor, and that the entry of nonsuit was therefore erroneous. (Carson v. Facilities Development Co., supra, 36 Cal.3d at pp. 838-839.)
Before we consider the merits of plaintiffs’ contention, however, we must confront two jurisdictional and procedural obstacles raised by PG & E.
PG & E contends a “determination” that it can be held strictly liable in tort is beyond the jurisdiction of this court because it would contradict an order of the Public Utilities Commission (PUC), whose decisions are reviewable only by our highest court. (Pub. Util. Code, § 1759; Waters v. Pacific Telephone Co. (1974) 12 Cal.3d 1, 4 [114 Cal.Rptr. 753, 523 P.2d 1161].) PG & E asserts the PUC has shielded it from liability for nonnegligent acts in rule 31.1 of General Order No. 95, as set out in the margin.2 PG & E’s argument, although ingenious, is totally without merit.
It has long been acknowledged that the PUC has the power, by rule, to limit the liability of utilities subject to PUC regulation and supervision. {Waters v. Pacific Telephone Co., supra, 12 Cal.3d at pp. 6, 10; Cole v. Pacific Tel. & Tel. Co. (1952) 112 Cal.App.2d 416, 417 [246 P.2d 686]; Davidian v. Pacific Tel. & Tel. Co. (1971) 16 Cal.App.3d 750, 757, fn. 3 [94 Cal.Rptr. 337].)
Although the PUC is empowered to limit utilities’ liability, we conclude it has not done so in rule 31.1. Rule 31.1 provides that electrical supply [78]*78and communication systems shall be maintained in safe condition and specifically imposes a duty of due care to minimize the hazards involved with overhead utility wires. (Perrine v. Pacific Gas & Elec. Co. (1960) 186 Cal.App.2d 442, 447 [9 Cal.Rptr. 45].) Manifestly, the rule imposes a duty of care and does not withdraw or limit liability. Moreover, the rule is in-apposite to the factual situation before us. This is not a case like Perrine, supra, where the plaintiff accidentally came into contact with the utility’s overhead wires; rather, in this case a transformer which simply happened to be on an overhead pole (as opposed to in an underground vault) malfunctioned and sent extraordinarily high voltage directly into the electrical system of plaintiffs’ home. Even if we were to read rule 31.1’s command to “be careful” with overhead wires to preclude liability without fault for overhead-wire accidents, we would not be justified in extending the rule’s reach to the facts of this case. We conclude rule 31.1 does not bar imposition of strict liability in tort when the electricity actually received by the consumer at her residence is dangerously in excess of her reasonable expectations and the utility’s intentions.
PG & E also contends that plaintiffs failed to plead their claim that the electricity itself, rather than the transformer, was the defective product at issue. PG & E correctly points out that plaintiffs’ complaint alleged their injuries were caused by defective electrical equipment, not defective electricity, and that plaintiffs never sought to amend their complaint.
The general and longstanding rule is that a party must recover on the cause of action he has alleged in his complaint and not on another cause of action disclosed by the evidence. (Barrere v. Somps (1896) 113 Cal. 97, 102 [45 P. 572]; Weissensee v. Chronicle Publishing Co. (1976) 59 Cal.App.3d 723, 729 [129 Cal.Rptr. 188].) However, the general rule may yield where a case is tried on the theory that a matter is in issue and evidence is received thereon without objection. (Weissensee, supra, 59 Cal.App.3d at p. 729; see People v. Toomey (1984) 157 Cal.App.3d 1, 11 [203 Cal.Rptr. 642]; 4 Witkin, Cal. Procedure (2d ed. 1971) Trial, § 336, p. 3138.)
“‘“It has long been settled law that where (1) a case is tried on the merits, (2) the issues are thoroughly explored during the course of the trial and (3) the theory of the trial is well known to court and counsel, the fact that the issues were not pleaded does not preclude an adjudication of such litigated issues and a review thereof on appeal.” ’ ” (People v. Toomey, supra, 157 Cal.App.3d at p. 11, quoting Davis v. Cordova Recreation & Park Dist. (1972) 24 Cal.App.3d 789, 794 [101 Cal.Rptr. 358].)
Here the issue of whether electricity is a product was tendered to the trial court in the following ways:
[79]*79The issue was first broached by PG & E itself in its trial brief and motion for nonsuit on the issue of products liability.3 This trial brief was made available to the trial court several days before the hearing on the motion for nonsuit. PG & E’s brief anticipated the argument eventually made by plaintiffs that electricity itself is a “product” for strict tort liability purposes. At the hearing on the motion, PG & E’s counsel called the trial court’s attention to the trial brief.
The trial court was also in possession of plaintiffs’ memorandum of points and authorities in support of their motion for directed verdict, which made the argument that electricity is a “product.”4 Plaintiffs’ memorandum in[80]*80completely cited Ransome v. Wisconsin Elec. Power Co., supra, 275 N.W.2d 641, which held electricity a “product” for strict tort liability purposes. The memorandum omitted citations to the appropriate reporters. At the hearing on the nonsuit motion plaintiffs’ counsel called the trial court’s attention to this memorandum and tendered to the trial court a copy of “that Wisconsin case,” undoubtedly referring to Ransome.
At the hearing on the nonsuit motion, counsel for PG & E again raised the argument that electricity was not a “product.”5 Counsel for plaintiffs responded to this argument.
The trial court indicated it had reviewed and was familiar with the respective authorities submitted on the products liability issue.
In light of the unambiguous argument set forth in the respective memoranda, the authorities cited therein, the arguments of counsel and the trial court’s expression of familiarity with those arguments, we have no doubt [81]*81plaintiffs’ contention that electricity was a “product” was tendered to opposing counsel and the trial court itself.
PG & E relies upon Lewis v. South S.F. Yellow Cab Co. (1949) 93 Cal.App.2d 849 [210 P.2d 62] for the proposition the trial court properly granted the nonsuit because plaintiffs failed to obtain leave to amend their complaint. A motion to amend would undoubtedly have been the prudent and lawyerlike thing to do. However, we note initially that leave to amend would in all likelihood have been granted since any amendment would have involved the “same general set of facts” as the original complaint, and PG & E had made no showing of prejudice. (Earp v. Nobmann (1981) 122 Cal.App.3d 270, 286 [175 Cal.Rptr. 767]; see Code Civ. Proc., §§ 469-471; Glaser v. Meyers (1982) 137 Cal.App.3d 770, 776-777 [187 Cal.Rptr. 242]; Godfrey v. Steinpress (1982) 128 Cal.App.3d 154, 174 [180 Cal.Rptr. 95].) Later authorities have not followed the strict rule of Lewis but have reasoned that if the proof is presented and the issue clearly tendered, the failure formally to amend the pleading is immaterial. (See Donovan v. Wechsler (1970) 11 Cal.App.3d 210, 213 [89 Cal.Rptr. 669]; 8 Cal. Practice (2d ed. 1981) Pleading—Civil Actions, § 1097, p. 405.) Here, we have no doubt that defendant and, more importantly, the trial court were fully put on notice and informed of plaintiff’s theory of liability. In these circumstances, the purpose of an amendment to the complaint was satisfied. Plaintiffs’ failure to amend does not bar their pursuit of liability on a theory that electricity was a defective product.
We come to plaintiffs’ major contention on appeal: that the electricity PG & E furnishes to consumers is a product rather than a service. (See Shepard v. Alexian Brothers Hosp. (1973) 33 Cal.App.3d 606, 608-609 [109 Cal.Rptr. 132]; Allied Properties v. John A. Blume & Associates (1972) 25 Cal.App.3d 848, 855 [102 Cal.Rptr. 259]; Cal. Products Liability Actions (rev. ed. 1984) § 2.02[1], p. 2-23.)
PG & E claims that electricity is merely the motion of charged ions and is not an “article” as described by Greenman. The courts, however, have not dwelled unduly on electricity’s physical properties.6 Over 20 years ago the California Court of Appeal recognized that “Electricity is a commodity which, like other goods, can be manufactured, transported and sold.” (Baldwin-Lima-Hamilton Corp. v. Superior Court (1962) 208 Cal.App.2d [82]*82803, 819 [25 Cal.Rptr. 798].)7 Although we have found no California case which has considered the issue in the strict tort liability context, the courts of other states have had little trouble in concluding that electricity delivered to homes and businesses is a “product.” (See, e.g., Petroski v. Northern Indiana Public Service Company (1976) 171 Ind.App. 14 [354 N.E.2d 736, 747]; Hedges v. Public Serv. Co. (Ind.App. 1979) 396 N.E.2d 933, 935; Ransome v. Wisconsin Elec. Power Co., supra, 275 N.W.2d at p. 647; Elgin Airport Inn v. Commonwealth, supra, 410 N.E.2d at p. 623; see also Farina v. Niagara Mohawk Power Corp. (1981) 81 App.Div.2d 700 [438 N.Y.S.2d 645, 646]; Genaust v. Illinois Power Company (1976) 62 Ill.2d 456 [343 N.E.2d 465, 469-470, 82 A.L.R.3d 285] [assuming arguendo that electricity is a “product”].) As the Supreme Court of Wisconsin aptly put it, “The distribution might well be a service, but the electricity itself, in the contemplation of the ordinary user, is a consumable product.” {Ransome v. Wisconsin Elec. Power Co., supra, 275 N.W.2d at p. 643.)
PG & E relies on Shepard v. Alexian Brothers Hosp., supra, 33 Cal.App.3d 606, and Fogo v. Cutter Laboratories, Inc. (1977) 68 Cal.App.3d 744 [137 Cal.Rptr. 417], to support its argument that provision of electricity is a service rather than a product. Both cases are readily distinguishable.
Shepard and Fogo relied in part on Health and Safety Code section 1606, which legislatively answered the question there presented, that supply of blood and blood products was a service rather than a sale. {Shepard, 33 Cal.App.3d at p. 609; Fogo, 68 Cal.App.3d at p. 752.) Shepard and Fogo also noted that some defects in blood products were inevitable, and that no policy reason existed to impose absolute liability on the supplier for defects it could not avoid. {Shepard, at pp. 611-612; Fogo, at pp. 752-753.) Here, evidence at trial suggested the accident could have been avoided through testing transformers but testing would have been more costly than the alternative.8
[83]*83We readily acknowledge that PG & E’s liability should not depend simply upon whether electricity is or is not labeled a “product.” More significantly, we believe the policy justifications for strict liability in tort support its imposition in this case. (See Daly v. General Motors Corp. (1978) 20 Cal.3d 725, 736 [575 P.2d 1162].) This court has identified four main policy grounds for the doctrine: (1) to provide a “short cut” to liability where negligence may be present but is difficult to prove; (2) to provide an economic incentive for improved product safety; (3) to induce the reallocation of resources toward safer products; and (4) to spread the risk of loss among all who use the product. (McDonald v. Sacramento Medical Foundation Blood Bank (1976) 62 Cal.App.3d 866, 874 [133 Cal.Rptr. 444]; see 50 Cal.Jur.3d, Products Liability, § 17, p. 809; see also Cronin v. J.B.E. Olson Corp. (1972) 8 Cal.3d 121, 133 [104 Cal.Rptr. 433, 501 P.2d 1153]; Escola v. Coca-Cola Bottling Co. (1944) 24 Cal.2d 453, 461-462 [150 P.2d 436] (Traynor, J., cone.).)
Proof of negligence in cases such as this requires a plaintiff to present to a jury evidence of the inner workings of an electrical power system of vast and complex proportions. The technical operation of such systems and of electricity itself is far beyond the knowledge of the average juror. The expert witnesses who can explain such systems to the jury are concentrated within the industry itself and may be reluctant to serve as expert witnesses in plaintiff’s cases. Moreover, PG & E is in a much better position than a consumer-plaintiff to diagnose—and ultimately to correct— the failures which inevitably occur in systems of such magnitude.
In addition, where, as here, a huge surge of injury-causing electricity is traceable to a defective component (the transformer) in the utility’s system, imposition of strict liability creates an incentive for utilities to avoid accidents before they occur, by investing in safer products. Although, as PG & E notes, its current practices and procedures are extensively regulated by the PUC and its General Order 95, the PUC has certainly not forbidden testing transformers before they are connected to 12,000-volt powerlines. Nothing in the record suggests the PUC is of the view that electric utility procedures are incapable of being made safer.
Finally, strict liability in tort spreads the costs of personal injuries among millions of consumers of electricity instead of imposing those costs upon blameless victims chosen by chance. It is proper that those who seek to benefit from a product should bear the associated costs and should not ask the unfortunate but inevitable victims selected (literally) by accident to bear the burden unaided.
We conclude that PG & E, as a commercial supplier of electricity, is subject to strict liability in tort for personal injuries caused by delivery [84]*84of electricity at dangerously high voltage due to a defective transformer. Accordingly, the trial court’s entry of nonsuit was error. (Carson v. Facilities Development Co., supra, 36 Cal.3d at pp. 838-839.)
We emphasize that our holding is limited to cases where the electricity is actually in the “stream of commerce,” and expected to be at marketable voltage. In most cases this will mean the electricity must be delivered to the customer’s premises, to the point where it is metered, although the many variations in electrical systems prevent our drawing a “bright line” at a particular point.9 We concur in the limitations uniformly adopted by other jurisdictions which have excluded the “antenna cases” [plaintiff, installing TV antenna, accidentally touches antenna to powerline] and the “plaintiff-touches-downed-power-line” cases from liability-without-fault because in those cases contact with the power line comes at a point where the electricity is not in the stream of commerce or is not in marketable form. (See Genaust v. Illinois Power Company, supra, 343 N.E.2d at p. 470; Farina v. Niagara Mohawk Power Corp., supra, 438 N.Y.S.2d at p. 646; Hedges v. Public Serv. Co. of Indiana, Inc., supra, 396 N.E.2d at p. 935.)10 Moreover, in such cases (as with cases where dangerously high voltage is attributable to acts of God), the utility generally cannot prevent the accident using reasonably available means. (Cf. Shepard v. Alexian Brothers Hosp., supra, 33 Cal.App.3d at pp. 611-612; Fogo v. Cutter Laboratories, Inc., supra, 68 Cal.App.3d at pp. 752-753.)
Nor do we have occasion in this case to examine whether a commercial supplier of electricity should be strictly liable for property damage or for any specie of damage caused by delivery of electricity at less than marketable voltage, i.e., damage caused by a “brown-out.” Those situations may well involve policy considerations not present in the scenario currently before us.11
[85]*85n
Plaintiffs also contend the trial court erred in denying their motion for directed verdict on the issue of ultrahazardous activity, as liability was established as a matter of law. Plaintiffs are mistaken.
The doctrine of ultrahazardous activity provides that one who undertakes an ultrahazardous activity is liable to every person who is injured as a proximate result of that activity, regardless of the amount of care he uses. (McKenzie v. Pacific Gas & Elec. Co. (1962) 200 Cal.App.2d 731, 736 [19 Cal.Rptr. 628]; see 4 Witkin, Summary of Cal. Law (8th ed. 1974) Torts, §§ 799-808, pp. 3096-3104.) The doctrine of ultrahazardous activity focuses not on a product and its defects but upon an activity intentionally undertaken by the defendant, which by its nature is very dangerous. In this case it is of course true that the ultimate result of the transformer failure was very hazardous: over 7,000 volts of electricity were sent into a residential electrical system designed for no more than 240 volts. However, the doctrine scrutinizes not the accident itself but the activity which led up to the accident—in this case, the maintenance of high-voltage powerlines and transformers. Thus, the issue is whether maintenance of high-voltage power systems by public utilities is an ultrahazardous activity. We conclude it is not.
Our Supreme Court has limited the doctrine of ultrahazardous activity to encompass only activities which are neither commonplace nor customary. (Luthringer v. Moore (1948) 31 Cal.2d 489, 498 [190 P.2d 1].) In this case the allegedly ultrahazardous activity has become pervasive and is now entirely commonplace. (See, e.g., Clark v. Di Prima (1966) 241 Cal.App.2d 823 [51 Cal.Rptr. 49] [water escaping irrigation ditch; no liability as ditches now in widespread use].) We therefore join the court in McKenzie v. Pacific Gas & Elec. Co., supra, 200 Cal.App.2d 731, in concluding that maintenance of electric power lines is not “ultrahazardous.” (P. 736.) The trial court’s refusal to direct a verdict for plaintiffs on this issue was proper.
HI
Plaintiffs next contend the trial court should have directed a verdict in their favor on the issue of implied warranty of fitness for particular purpose (Cal.U.Com.Code, § 2315). Nothing in plaintiffs’ complaint indicated they were pursuing a theory of implied warranty. We conclude that this issue, unlike the products liability and ultrahazardous activity issues, involved questions of fact and law which were outside plaintiffs’ pleadings and were not fairly tendered to defendant at trial.
[86]*86The implied warranty of fitness for particular purpose has been codified in section 2315 of the California Uniform Commercial Code, which provides that “Where the seller at the time of contracting has reason to know any particular purpose for which the goods are required and that the buyer is relying on the seller’s skill or judgment to select or furnish suitable goods, there is unless excluded or modified under the next section an implied warranty that the goods shall be fit for such purpose.” (Italics added.)12 The next section, section 2316, provides in pertinent part that “to exclude or modify any implied warranty of fitness the exclusion must be by a writing and conspicuous. Language to exclude all implied warranties of fitness is sufficient if it states, for example, that ‘There are no warranties which extend beyond the description on the face hereof.’” (Cal.U.Com.Code, § 2316, subd. (2).) Section 2316 also provides that “An implied warranty can also be excluded or modified by course of dealing or course of performance or usage of trade.” (Cal.U.Com.Code, § 2316, subd. (3)(c).)
Plaintiffs first raised the implied warranty issue in their motion for directed verdict filed some four years after their complaint. Plaintiffs’ motion did not allege that the implied warranty was not excluded or modified pursuant to section 2316, nor did plaintiffs present any evidence at trial suggesting the implied warranty was in force at the time of the accident.
PG & E objected that the implied warranty issue was not timely raised. PG & E observed that unanswered questions remained as to the status of any implied warranty and noted that no discovery had been undertaken on the issue. Unlike the products liability issue, the particulars of the implied warranty issue were neither “well known to court and counsel” nor “thoroughly explored during the course of the trial.” (.People v. Toomey, supra, 157 Cal.App.3d at p. 11.) That being the case, plaintiffs’ failure to plead the implied warranty issue bars recovery on that ground. {Barrere v. Somps, supra, 113 Cal. at p. 102; Weissensee v. Chronicle Publishing Co., supra, 59 Cal.App.3d at p. 729.) The trial court’s refusal to direct a verdict on the issue was proper.
IV
Plaintiffs finally raise two instructional errors on the negligence cause of action. Plaintiffs’ claim the trial court erred in refusing to instruct [87]*87with a modified form of BAJI No. 9.21, dealing with commercial suppliers’ duty of reasonable care.13 The instruction provides, in part, that the supplier must exercise reasonable care in testing and inspecting component parts made by others.
In light of our conclusion in part I, ante, that electricity is a “product,” we hold that plaintiffs’ requested instruction was a correct statement of the law. PG & E contends, however, that the instruction was duplicative of matters adequately covered in other instructions and that its omission was harmless error. We agree with PG & E.
The trial court instructed with BAJI Nos. 3.10, 3.11, 3.12, and plaintiffs’ instruction based on PUC rule 31.1.14 Although the proffered instruction focused more clearly than the others upon the commercial supplier’s duty to perform reasonable testing and inspection of component parts furnished
[88]*88by others, we conclude the point is adequately covered in plaintiffs’ instruction based on PUC rule 31.1, which requires that entire electrical systems, necessarily including all component parts, be in such condition as to operate safely. (See fn. 14, ante.) We cannot say, after examining the entire cause, that it is reasonably probable a result more favorable to plaintiffs would have been reached had the proposed instruction been given. (Seaman’s Direct Buying Service, Inc. v. Standard Oil Co. (1984) 36 Cal.3d 752, 770 [206 Cal.Rptr. 354, 686 P.2d 1158]; see LeMons v. Regents of University of California (1978) 21 Cal.3d 869, 876 [148 Cal.Rptr. 355, 582 P.2d 946].)
Plaintiffs finally contend the trial court erred in refusing to instruct with BAJI No. 3.45 (negligence per se—violation of a statute) based upon PUC rule 31.1. However, rule 31.1 is merely a statement of the common law rule of due care and cannot be the basis of negligence per se. (Perrine v. Pacific Gas & Elec. Co., supra, 186 Cal.App.2d at p. 447; Lewis v. Pacific Gas & Electric Co. (1949) 95 Cal.App.2d 60, 63 [212 P.2d 243].) The trial court correctly refused the instruction.
Disposition
The judgment (order) granting nonsuit on the issue of strict liability in tort is reversed and the matter is remanded for further proceedings consistent with this opinion. In all other respects the judgment is affirmed.
Sparks, J., concurred.