These actions were brought to recover damages for the alleged wrongful deaths of three workmen occurring as the result of an explosion in the power plant of the defendant Consolidated Edison Company (Con Ed). The jury, following a trial of the actions, rendered a verdict in favor of said defendant, and the plaintiffs appeal from the judgments entered upon snch verdict.
The decedents, at the time of the accident, as employees of a subcontractor, were engaged in removing an existing manual lever or operating handle and interlock assembly located on the outside of the switch disconnection box of a substation on the ninth floor of the Con Ed building. The workmen intended to *167substitute a lever and interlock assembly of a more suitable type. The lever and assembly were used to control the shaft which, when turned to an “on” position, connected the live cables with the contact blades in the box. The work entailed the removal of a plate in order to separate the interlock assembly from the switch box compartment. The plate was located on the outside of the box but the workmen were required to remove a set screw and four bolts holding the assembly and plate to the box. Although the switch box on the primary or intake-side was connected with a current of 13,800 volts at the time of the work, there was testimony that the outside of the switch box was completely safe to touch; that it was a '‘ simple job ”; that an oil seal, acting as a friction on the pivot of the shaft, would prevent free movement of the shaft from an “ off ” position; and that the work could be accomplished without activating any of the interior contents of the switch box and without danger to the workmen.
It was agreed that Con Ed should take two steps in preparation for the work, viz: (1) Open the circuit breaker on the secondary or outage side from the transformer to prevent the possibility of a power flow reversal from the low tension or 2,400 volt side of the transformer; and (2) open the interlock on the outside of the disconnect switch box, that is, to place it in an open or off position so that the current coming in to the substation would be cut off at the terminals in the box. It clearly appears that these preliminary steps were fully complied with prior to the entry by the decedents into the substation room.1
Con Ed further suggested that the cables entering the substation be de-energized for the purpose of the work by the decedents, but the supervisory engineer (not under direction or control of Con Ed)2 and the subcontractor, with the acquiescence of the decedent Braun, deliberately chose to do the work without the cutting off of the current.
The decedents were the only persons present at the substation at the time of the accident. Although there is no eyewitness testimony as to what the decedents were actually doing at the time of the explosion, it may be inferred that they were then *168working on the equipment. There is evidence that the work had progressed to the extent of a removal of the lever on the outside of the switch box, a removal of some of the bolts, and a loosening of the plate on the box. The cause of the explosion was not established but it appears that the explosion erupted in the switch box or in the pothead compartment located just below the switch box.
The plaintiffs tried the case on the theory of res ipsa loquitur and the issues of negligence and contributory negligence were submitted to the jury. The plaintiffs urge that it was error to submit the issue of contributory negligence to the jury and that, in any event, the verdict was clearly against the weight of the evidence. We conclude that these contentions lack merit and that the judgments entered on the verdict of the jury should be affirmed.
The evidence supports a finding that the decedents, who were experienced electricians, entered upon and engaged in the performance of the work on the lever and plate located on the switch box in the substation with the knowledge that an electric current of very high voltage was connected with and entering into the bushings and terminals in the box. The jury could find that the decedents voluntarily assumed an unnecessary risk in doing their work. This could constitute contributory negligence which, simply defined, “ is conduct which involves an undue risk of harm to the actor himself.” (Prosser, Torts [3d ed.], § 64, p. 428.) “ [I]t is clear that where a person can choose between one of two courses to follow, one of which exposes him to danger and the other of which does not, he may be held guilty of contributory negligence if he chooses the dangerous course. In general, what constitutes knowledge and appreciation of the danger is a question of fact.” (Utica Mut. Ins. Co. v. Amsterdam Color Works, 284 App. Div. 376, 379, affd. 308 N. Y. 816. See, also, Seidman v. M & R Air Conditioning Corp., 15 N Y 2d 814; Townes v. Park Motor Sales, 7 A D 2d 109, 112-114, affd. 7 N Y 2d 767.)
There is no validity to the plaintiffs’ point that it was improper in this case to submit the contributory negligence issue to the jury. The alleged contributory negligence of an injured or decedent, and the causal relationship thereof to the injury or death, are matters for consideration in every case submitted on the theory of res ipsa loquitur. “ Allied to the condition of exclusive control in the defendant [essential in a res ipsa case.] is that of absence of any action on the part of the plaintiff contributing to the accident. Its purpose, of course, is to eliminate the possibility that it was the plaintiff who was responsible.” (Prosser, Torts [3d ed.], § 39, p. 228; see, also, 4 Bender’s New *169York Evidence, § 230.07[1], p. 187; Corcoran v. Banner Super Market, 19 N Y 2d 425, 430; Minotti v. State of New York, 6 A D 2d 990.)
Generally, also, in a res ipsa loquitur case, the issues pertaining to the alleged contributory negligence of the injured or decedent present questions of fact. In such a case, it is the function of the jury to draw, weigh and resolve all such inferences as might be deduced by a reasonable mind from the proven facts and circumstances. (See Witkowicz v. Amalgamated Props., 264 App. Div. 156, 160.) When varying inferences are present, a jury question is raised. (See Foley v. State of New York, 294 N. Y. 275, 280.) Therefore, where reasonable inferences would support a finding that the negligence of an injured or a decedent may have contributed to his injury or death, the issue of contributory negligence is properly submitted to the jury.
The right of Con Ed to have the jury in this case pass upon all reasonable inferences would have been defeated by a matter of law dismissal of the defense of contributory negligence. Such dismissal would amount to an unjustifiable matter of law holding that the decedents incurred no danger in working on the switch box without a de-energizing of cables. Furthermore, the dismissal would have (constituted a factual determination that the explosion was caused not by acts of the decedents relating to danger incurred by them, but by events which occurred outside of the substation and which were under the control of Con Ed. Thus, the dismissal would have had the effect of invading the province of the jury in the matter of resolving the inferences bearing on the question, as to the cause of the explosion.
As noted, the cause of the accident was not established and we do not know whether the explosion was triggered by events occurring in or outside of the substation. The plaintiffs did not prove and do not claim that the deaths of the decedents resulted from a particular negligent act or omission which would be unrelated to the danger voluntarily assumed by them. Also, it is not known with matter of law certainty that the decedents did not incur any risk in what they actually did under the conditions assumed by them. There being no proof as to what actually happened, the testimony that the proposed work did not involve any danger may not be given the effect of taldng the issue of contributory negligence out of the case. Rather, such testimony would support an inference that if the decedents had performed their work properly, there would have been no danger and the explosion would not have occurred.
Under the circumstances, there is even arguable basis for Con Ed’s contention that the record supports a holding that the *170decedents were guilty of contributory negligence as a matter of law. In any event, if plaintiffs’ case merited submission to the jury, the inferences bearing upon the contributory negligence of the decedents and the causal relationship thereof to their deaths, were properly submitted along with the inferences claimed to establish the negligence of Con Ed.
Nevertheless, we conclude that, irrespective of the defense of contributory negligence, the judgments are sustainable on the ground that there was no prima facie proof of actionable negligence on the part of Con Ed. The plaintiffs failed to establish a case on the theory of res ipsa loquitur and Con Ed’s motion, made at the close of the case for a directed verdict, should have been granted.
It is settled, as hereinbefore noted, that, among the conditions necessary for the application of the doctrine of res ipsa loquitur, are the requirements that the accident “ must be caused by an agency or instrumentality within the exclusive control of the defendant ’ ’ and that the accident ‘ ‘ must not have been due to any voluntary action or contribution on the part of the plaintiff.” (Corcoran v. Banner Super Market, 19 N Y 2d 425, 430, supra.) Here, Con Ed was in control of the electric current which entered the substation but, at the time of the explosion, Con Ed was not in sole possession and control of the substation or of its components. There was no showing that the cause of the explosion was an improper flow or mishandling of the electric current, such as an overload or “ a violent charge of electricity ”, chargeable to Con Ed. (Cf. Manley v. New York Tel. Co., 303 N. Y. 18, 25.) Inasmuch as there was no such showing, it is not reasonable to infer that Con Bid’s negligence was the probable cause of the accident. (Cf. Corcoran v. Banner Super Market, supra.) If anything, it is a stronger inference that nothing would have happened if the defendants did their work properly.
The decedents were the only persons present at the time when they were working upon the equipment. For all that appears in the record, the explosion may have been occasioned by a short or arcing resulting from the activities of the decedents, including from an inadvertent loosening of the pivot of the shaft enabling a connection with the contact blades. Certainly, their responsibility for the accident was not eliminated.
This is a case where the probabilities point equally to a cause for which defendant is not responsible a,s they do to defendant’s negligence. (See Galbraith v. Busch, 267 N. Y. 230.) The matter was “ left in doubt and it is just as probable that the injury was the result of one cause [here, the acts of decedents'] as the *171other [negligence of Con Ed].” ["Therefore,] there can "be no recovery ” (Ruback v. McCleary, Wallin & Crouse, 220 N. Y. 188, 195). In fact, a finding that Con Ed was negligent rests on “ mere speculation, guess or surmise [citing cases]. The defendant [Con Ed] is not an insurer (Storm v. New York Tel. Co., 270 N. Y. 103), and the mere fact that an accident has happened and that injury followed does not give rise to a presumption of negligence on the part of the one charged [Con Ed] ” (Manley v. New York Tel. Co., supra, p. 25).
The happening of the second explosion, following the accident (the first explosion) does not tend to establish negligence charging Con Ed with responsibility for the first explosion. Ooncededly, the second explosion resulted from Con Ed’s inadvertent application of power after it became aware of the damage resulting from the first explosion. The power, so applied, caused the second explosion when it entered the circuits where a “ short ” existed due to the damage. The explanation of the cause of the second explosion negates the existence of any relationship with the cause of or alleged negligence in the unexplained initial explosion.
Finally, if the plaintiffs did establish a prima facie case on the theory of res ipsa loquitur, the jury has resolved the pertinent issues in Con Ed’s favor. Although Con Ed did rest o:n the close of plaintiffs’ case, there was a probing into the cause and the alleged responsibility for the accident in the examination and cross-examination of Con Ed’s former electrical power supervisor who, at the time of the accident, was in charge of the operation of the plant equipment in the particular building. Also, there was received the testimony of Con Ed’s general superintendent of the building and of the manager for the engineer supervising the improvement work in the plant. Con Ed was not bound to produce other witnesses in rebuttal of plaintiffs ’ alleged case. (See Davis v. Goldsmith, 19 A D 2d 514.) "[S]trictly speaking, res ipsa loquitur is an evidentiary rule which merely permits an inference of negligence and satisfies the plaintiff’s duty of producing evidence sufficient to go to the jury, but does not create a full presumption and is ordinarily not sufficient, even where the defendant produces no evidence in contradiction or rebuttal, to entitle the plaintiff to the direction of a verdict.” (41 N. Y. Jur., Negligence, § 89.) The court is not entitled to hold "that the jury had no reasonable recourse except to find in favor of plaintiff” (Lo Piccolo v. Knight of Rest Prods. Corp., 7 A D 2d 369, 375, affd. 9 N Y 2d 662).
The jury was not bound to accept as true and unexplained the excerpts of testimony favorable to plaintiffs, that have now been *172culled from the record by the dissenting Justice. The case was to be decided on the record as a whole. “ It is settled [by a long line of cases] that a jury verdict in favor of defendant may not be set aside unless it plainly appears that the evidence so preponderates in favor of the plaintiff that the verdict for the defendant could not have been reached on any fair interpretation of the evidence.” (Marton v. McCasland, 16 A D 2d 781, 782, citing cases. See, also, Smith v. McIntyre, 20 A D 2d 711, citing cases; Carino v. Marino, 28 A D 2d 514.)
We affirm the findings of fact implicit in the jury’s verdict. The judgments for the defendant Consolidated Edison Company should be affirmed, without costs and disbursements.
. This is not disputed. Indeed, plaintiffs argue their appeal on the basis of the “ uncontradioted testimony that the interior electrical contact blades had been separated from the bushings on the pivot prior to the commencement of the decedents’ assigned work (by .the placement of the lever in an open position)
. The power plant, which had been owned by the City of New York, was transferred by it to Con Ed some months before the accident, subject to completion by the Transit Authority of the city of certain contracts for the improvement of the facilities of the plant; and the engineer supervising the work was acting in behalf of the Transit Authority under contract with the city.