E. D.-Lewis and Beulah B. Lewis, his wife, were the owners of a nearly completed wood and brick veneer residence, which was under construction in Yakima county. Vernon H. Scott, doing business as Yakima Sheet Metal Works, was engaged in the business of selling, installing, and servicing heating equipment for dwellings. He sold a Montag constant-ignition type oil burning furnace to the Lewises, and installed it in the dwelling shortly prior to December 23, 1954. During the noon hour of December 23rd, a fire broke out directly from the furnace and destroyed the entire building, including carpenter tools and equipment belonging to the workmen and the owner.
December 27, 1954, a chemical engineer, experienced in fire investigations, examined the debris for the purpose of ascertaining the cause of the fire. His investigation disclosed that, in the installation of the furnace and its connection with the oil tank, the suction and return lines had been crossed. The suction line extended into the tank about four inches. The return line, which carried excess oil and air *854from the pump to the tank, extended nearly to the bottom of the tank. The engineer concluded that the excess oil and air thus pumped into the bottom of the tank created a bubbling condition therein; that, while the furnace was burning and after the oil in the storage tank had been lowered, four inches to the bottom of the suction line, the pump intermittently drew oil and air through it to the furnace burner, and that this process produced oil vaporization in excess quantities, causing the explosion which resulted directly in the destruction of the building by fire.
The Lewises and the workmen instituted this action for damages, alleging, inter alia, that the defendant, Vernon H. Scott, was negligent in installing the furnace, and that his negligence was the sole and proximate cause of the damage. The defendant’s answer denied liability.
The cause was tried to the court, which found, inter alia, the following material facts:
Finding of Fact No. 2: “That prior to and at the time in question, defendant Vernon H. Scott . . . was engaged in the business of selling, installing and servicing heating equipment, including oil furnaces for dwelling -houses; . . . That defendant held himself out to be skilled in such installations. That the said furnace . . . was resold to plaintiff, E. D. Lewis, by defendant, who installed the same in the partially completed residence of said plaintiff, ...”
Finding of Fact No. 3: “. . . That at the time the defendant and his employee installed and connected the suction and return lines between the oil burner pump and the tank, the same were mistakenly reversed by installing the line attached to the suction side of the pump so that it extended only approximately four inches down from the top of the tank, and by installing the return line, attached to the return port on the pump, so that the other end extended into the -tank to a point about two inches above the bottom. That in actuality said two lines were reversed by defendant at the time of their installation. . . . ”
Finding of Fact No. 6: “ . . . That the effect thereof was to cause a spurting of oil, of air, and of oil and air, through the nozzle into the fire box in an atomized form, differing from a proper mixture thereof to the extent that the same 'was not constantly being ignited by the constant *855igniters then and there in operation at the end of the nozzle. That this process in turn produced vaporization in excess quantities in the fire box, and when the same was ignited, caused a rapid combustion of sufficient intensity to blow off an elbow from the sheet metal smokestack leading from furnace to chimney, and to cause the door of the furnace to fall open, and the escape from said furnace and stack line of ignited vapors and flames, resulting in the destruction of the dwelling by fire.”
Finding of Fact No. 10: “That there was no defect in the furnace, nor in any of the component parts of the furnace assembly, including the Protectorelay, burner and pump. That the only defect present was the crossing of the suction and return lines, which, under the circumstances present, permitted air in minute quantities to pass through the pump and nozzle into the combustion chamber of the furnace. That the said Protectorelay, under the conditions present, did not prevent operation of the pump and burner so as to preclude accumulation of excess unignited vapors in said combustion chamber. That the said Webster pump did not prevent, under conditions present, intermittent spurts of oil, of air, and of oil and air of improper mixture, from being introduced into the combustion chamber. . . .”
Finding of Fact No. 12: Damages to the respective plaintiffs were itemized as follows: Klomp Bros. $636.80, Har-toon & Sons $161, and the Lewises $79.55 and $13,636.58.
Finding of Fact No. 4: “ . . . prior to the fire in question the only result of such crossing, within the knowledge of the witnesses testifying, has been to cause the furnace to cease operating when oil in the tank is consumed to a point just below the end of the line in the tank which leads to the intake port on the burner, the only effect being the same as running out of oil when the lines are properly installed.”
Finding of Fact No. 9: “That at no time prior to the fire did defendant himself have knowledge that the lines were crossed, or that such crossing would or might create any dangerous condition. ...”
From these facts, the court concluded:
"... That there was no reason at any time prior to the fire in question to suspect, anticipate, or know the said crossing of the lines would result in the fire in question [a conclusion, although part of finding of fact No. 10]. . . .
*856“That the actual-damage resulting from the crossing of the fuel lines was not a result, nor even in the general field of danger, which defendant should have reasonably foreseen or anticipated as a result of crossing of said lines; and therefore defendant is not liable to plaintiffs herein.”
From the judgment of dismissal, the plaintiffs have appealed.
No error is assigned to the court’s findings of fact. They are, therefore, the established facts of the case.
The appeal presents a single issue of law: Did the trial court err in concluding, as a matter of law, that the injury sustained by the appellants is not compensable, as the resulting damage was not a foreseeable consequence of the negligence of the defendant?
The elements of actionable negligence are (1) the existence of a duty, (2) the breach thereof, which must be a proximate cause of the injury, and (3) the resulting damage. Pate v. General Electric Co., 43 Wn. (2d) 185, 260 P. (2d) 901 (1953); McCoy v. Courtney, 25 Wn. (2d) 956, 172 P. (2d) 596, 170 A. L. R. 603 (1946); 65 C. J. S. 324, § 2.
Do the findings of fact in the instant case establish these elements?
Findings Nos. 2 and 3 establish ■ the first two elements of actionable negligence, (1) the duty to install the furnace properly, and (2) the breach of that duty by the reversal of the lines. Findings Nos. 6 and 10 establish that the breach was the sole and proximate cause of the damage. Finding No. 12 establishes the third element, the resulting damages to the respective appellants. Thus, all of the elements establishing actionable negligence were found by the court to be present. Nevertheless, the court concluded therefrom that there was no liability because the result was unforeseeable, and, in its memorandum opinion, relied upon four decisions of this court. The cited cases are not apropos to the issue presented here for the following. reasons:
(a) In Ullrich v. Columbia & Cowlitz R. Co., 189 Wash. 668, 66 P. (2d) 853 (1937), the plaintiff alleged that the de*857fendant railroad company had breached its duty to him by not having proper warning devices at a railroad crossing. The court held that there was no breach of duty to warn because, “When a train actually occupies the crossing, that in itself supersedes all other warnings and gives actual notice by its own presence.”
(b) Eckerson v. Ford’s Prairie School Dist. No. 11, 3 Wn. (2d) 475, 101 P. (2d) 345 (1940), Berglund v. Spokane County, 4 Wn. (2d) 309, 103 P. (2d) 355 (1940), and McLeod v. Grant County School Dist. No. 128, 42 Wn. (2d) 316, 255 P. (2d) 360 (1953), involve reasonable foreseeability as to intervening causes, which issue is not here present.
Results which follow in unbroken sequence (without an intervening efficient cáuse) from the original negligent act, are natural and proximate. The wrongdoer is responsible for the results, even though he could not have foreseen the- consequences of his original negligent act. Hellan v. Supply Laundry Co., 94 Wash. 683, 690, 163 Pac. 9 (1917), 1 Cooley on Torts (4th ed.) 140, § 53. See, also, Schatter v. Bergen, 185 Wash. 375, 55 P. (2d) 344 (1936); 2 Restatement, Torts, 1173, § 435.
This rule has been adopted in other jurisdictions. See Chicago, Milwaukee, St. Paul & Pac. R. Co. v. Goldhammer, 79 F. (2d) 272 (1935); Affolder v. New York, Chicago & St. Louis R. Co., 79 F. Supp. 365 (1948); Monterrosa v. Grace Line, Inc., 90 Cal. App. (2d) 826, 204 P. (2d) 377 (1949); Lynch v. Fisher, 34 So. (2d) (La. App.) 513 (1948); Campbell v. Pittsburgh, 155 Pa. Super. Ct. 439, 38 A. (2d) 544 (1944); Daugherty v. Hunt, 110 Ind. App. 264, 38 N. E. (2d) 250 (1941); Mrazek v. Terminal R. Ass’n, 341 Mo. 1054, 111 S. W. (2d) 26 (1937); Shipley v. Pittsburgh, 321 Pa. 494, 184 Atl. 671 (1936).
Applying this rule to the facts in the instant case, liability attaches as a result of the negligent crossing of the lines, even though there was no evidence that a dwelling had previously been destroyed as a result of such a breach of duty. Where, as here, the undisputed facts establish *858that it did happen this time, the wrongdoer cannot shelter himself from liability under the defense that the actual consequence was one that he did not know would occur as a result of his negligence.
The court found that the respondent held himself out to be an expert in the field of furnace installation. The knowledge of a reasonably prudent expert is imputed to him. As such, he knew or should have known that improperly controlled vaporization in a furnace creates a dangerous and hazardous condition, and that, if such a condition exists in a furnace fire box and sparks from the ignition system come in contact with the vaporized oil, an explosion of unlimited intensity is the natural and direct result. The respondent could well have anticipated that damage would flow from his careless act, if nothing more than the inconvenience and delay in his installing the furnace properly, or the cost of proper installation in the event respondent refused to do so. Likewise, respondent could reasonably have forseen that the faulty installation in December could have resulted in damage to appellants from the failure of the furnace to function, cáusing a lack of heat to protect the plaster or other finish work and to prevent the freezing of the water system in the dwelling. Some damage was foreseeable from his breach of duty, even though the exact extent thereof was not anticipated. In the light of respondent’s expert knowledge, reasonable foreseeability of damage to others existed. See Harvey v. Auto Interurban Co., 36 Wn. (2d) 809, 220 P. (2d) 890 (1950); Carley v. Allen, 31 Wn. (2d) 730, 198 P. (2d) 827 (1948); Burr v. Clark, 30 Wn. (2d) 149, 190 P. (2d) 769 (1948); Hunter v. Quality Homes, 45 Del. 100, 68 A. (2d) 620 (1949); Arkansas Machine & Boiler Works v. Moorhead, 136 Ark. 18, 205 S. W. 980, 1 A. L. R. 1652 (1918); Prosser on Torts (2d ed.) 124, 131 et seq., § 31.
What we have heretofore said with reference to breach of duty does not emanate from a breach of a contractual relationship. In the law of negligence, liability attaches to the wrongdoer because of his breach of duty in *859performing his work negligently, which results in injury to others. In Hunter v. Quality Homes, supra, the court said [p. 107]:
"... Matters of common knowledge warn the installer that, if his work is done negligently, some one is likely to be injured. Faced with this warning, he assumes a certain duty to others — the duty to do the work with reasonable care and diligence — for the breach of which the law imposes a liability. This liability is based not upon contract but upon negligence. ...”
Prosser on Torts (2d ed.) 491, § 83, states:
“. . . When goods are sold by one person to another, it is now well established that the seller is under a duty to exercise the care of a reasonable man of ordinary prudence to see that the goods do no harm to the buyer. This duty, while it arises out of the relation created by the contract, is not identical with the contract obligation, but is merely a part of the general responsibility, sounding in tort,
Assuming that the loss is greater than the wrongdoer anticipated, the one whose negligent act caused the injury should bear the loss. Prosser on Torts (2d ed.) 262, § 48. In the instant case, the fact that the wrongdoer did not realize, at the time of the installation, that he had crossed the lines does not relieve him of liability. Actionable negligence, based upon a wrongdoer’s lack of due care, does not include the establishment of an element of intent.
“ ‘Negligence is conduct, and not a state of mind.’ In most instances, it is caused by heedlessness or carelessness, which makes the negligent party unaware of the results which may follow from his act.” Prosser on Torts (2d ed.) 119, § 30.
We conclude that unforeseeability of the consequences of a breach of duty to the person for whom it is to be performed does not relieve the wrongdoer of liability, when all of the elements of actionable negligence are established.
, We have not discussed those cases which involve the issue of unforeseeable plaintiffs, such as Palsgraf v. Long Island *860R. Co., 248 N. Y. 339, 162 N. E. 99, 59 A. L. R. 1253 (1928), since that issue is not here present. Neither have we discussed those cases which involve the issue of unforesee-ability of concurring or intervening causes of third parties as being within the general field of damages, such as Ecker-son v. Ford’s Prairie School Dist. No. 11, supra, Berglund v. Spokane County, supra, McLeod v. Grant County School Dist. No. 128, supra, and Kennett v. Yates, 41 Wn. (2d) 558, 250 P. (2d) 962 (1952), except .to state that they are not apropos, as that issue likewise is not here present.
Finally, respondent contends that the evidence sustains the court’s conclusions, although its findings of fact do not support them, and that, under the established rule, the trial court should be affirmed.
We find no merit in this contention for the reason that there is substantial evidence in the record which sustains the trial court’s findings of fact. Williams Tilt-Up Contractors, Inc. v. Schmid, 52 Wn. (2d) 429, 326 P. (2d) 41 (1958), and case cited.
The amount of the damages resulting from the injury has been stipulated by counsel for the respective parties and incorporated in the findings of fact. The judgment is reversed, and the cause remanded with instructions to enter judgment for the appellants.
Weaver, C. J., Hill, and Rosellini, JJ., concur.