On appeal, defendants assign as error the deputy commissioner’s Findings of Fact Nos. 6, 7, 8 and 9 for the reason that they were not supported by competent evidence. In reviewing the findings found by a deputy commissioner or by an individual member of the Commission when acting as a hearing commissioner, the Commission may review, modify, adopt, or reject the findings of fact found by the hearing commissioner. The Commission is the fact-finding body under the Workmen’s Compensation Act. Lee v. Henderson & Associates, 284 N.C. 126, 200 S.E. 2d 32 (1973); Brewer v. Trucking Co., 256 N.C. 175, 123 S.E. 2d 608 (1962); G.S. 97-85. Here, the facts found by the deputy commissioner were adopted by the Commission as its own. Under G.S. 97-86, this award became conclusive and binding as to all questions of fact.
The only injury which is compensable under the Workmen’s Compensation Act is an “injury by accident arising out of and in the course of the employment.” G.S. 97-2(6). In interpreting this statute, our Court, in Conrad v. Foundry Company, 198 N.C. 723, 726, 153 S.E. 266, 269 (1930), stated:
“. . . The words ‘out of’ refer to the origin or cause of the accident and the words ‘in the course of’ to the time, place, and circumstances under which it occurred. [Citations omitted.] There must be some causal relation between the employment and the injury; but if the injury is one which, after the event, may be seen to have had its origin in the employment, it need not be shown that it is one which ought to have been foreseen or expected. [Citation omitted.] . . .” See Lee v. Henderson & Associates, supra.
*281Unquestionably, in present case, plaintiff’s injury by accident occurred “in the course of” his employment. It occurred on 18 October 1973 when, as required by the terms of his employment, he was on duty at the No. 3 Fire Station in Wilmington, North Carolina. As stated in 1 Larson, Workmen’s Compensation Law § 24.00 (1972), “[w]hen an employee is required to live on the premises, either by his contract of employment or by the nature of the employment, and is continuously on call (whether or not actually on duty), the entire period of his presence on the premises pursuant to this requirement is deemed included in the course of employment. . . .”
The determinative question in present case is whether plaintiff’s injury arose “out of” his employment. This Court, in Robbins v. Nicholson, 281 N.C. 234, 238-39, 188 S.E. 2d 350, 354 (1972), said:
“An accident occurring during the course of an employment . . . does not ipso facto arise out of it. The term ‘arising out of the employment’ is not susceptible of any all-inclusive definition, but it is generally said that an injury arises out of the employment ‘when it is a natural and probable consequence or incident of the employment and a natural result of one of its risks, so there is some causal relation between the injury and the performance of some service of the employment.’ Perry v. Bakeries Co., 262 N.C. 272, 274, 136 S.E. 2d 643, 645 (1964). . . .” See also Lee v. Henderson & Associates, supra.
Together, the phrases “arising out of” and “in the course of” are used in an attempt to separate work-related injuries from non-work-related injuries. Both tests are part and parcel of the single problem of determining the relationship between injury and employment.
“In practice, the ‘course of employment’ and ‘arising out of employment’ tests are not, and should not be, applied entirely independently; they are both parts of a single test of work-connection, and therefore deficiencies in the strength of one factor are sometimes allowed to be made up by strength in the other.” 1 Larson, Workmen’s Compensation Law § 29.00 (1972).
*282In Guest v. Iron & Metal Co., 241 N.C. 448, 85 S.E. 2d 596 (1955), this Court said:
“The Act ‘should be liberally construed to the end that the benefits thereof should not be denied upon technical, narrow and strict interpretation,’ Johnson v. Hosiery Co., 199 N.C. 38, 153 S.E. 591; but ‘the rule of liberal construction cannot be employed to attribute to a provision of the act a meaning foreign to the plain and unmistakable words in which it is couched,’ Henry v. Leather Co., 231 N.C. 477, 57 S.E. 2d 760.”
 Whether an accident arises out of the employment is a mixed question of fact and law, and the finding of the Commission is conclusive if supported by any competent evidence; otherwise, not. Lee v. Henderson & Associates, supra; Cole v. Guilford County, 259 N.C. 724, 131 S.E. 2d 308 (1963).
In the case of Lee v. Henderson & Associates, supra, plaintiff, a salesman employed by a cabinet manufacturer, worked in his employer’s shop during his training period and obtained permission from his superiors to build a doghouse for his own use from scrap material during working hours when he had nothing else to do. Each of the employer’s salesmen was required to work in the shop every third Saturday. While on duty in the shop one Saturday, plaintiff had cut some cabinet parts. During a lull, he resumed work on his uncompleted doghouse and injured himself with an electric saw. A practice or custom had been established by the employer allowing its employees to use its equipment for personal projects. This Court, speaking through Chief Justice Bobbitt, stated:
“The rule applicable when the employee has been directed, as part of his duties, to remain in a particular place or locality until directed otherwise or for a specified length of time, has been well stated by the Court of Appeals of New York in Davis v. Newsweek Magazine, 305 N.Y. 20, 28, 110 N.E. 2d 406, 409 (1953), as follows: ‘In those circumstances, the rule applied is simply that the employee is not expected to wait immobile, but may indulge in any reasonable activity at that place, and if he does so the risk inherent in such activity is an incident of his employment.’ . . .”
In Stubblefield v. Construction Co., 277 N.C. 444, 177 S.E. 2d 882 (1970), an employee of an electrical construction com*283pany was fatally injured on the premises of the Cherokee Brick Company. While awaiting the return of his foreman, the employee was standing in a room where several conveyor belts were in operation. The employee, while using his idle time to knock dust and pieces of brick from the conveyor rollers with a pair of pliers, came into contact with the conveyor and received fatal injuries. Compensation was awarded.
In Guest v. Iron & Metal Co., supra, the employee went to a filling station to use the free air facilities in order to repair a tire for his employer. While there, the filling station operator asked the employee to assist him in pushing an automobile off the filling station premises. The employee was injured when he was struck by another automobile while pushing the stranger’s automobile. We held that the injuries to the employee arose “out of and in the course of” his employment and were therefore compensable since the employee’s acts were to an appreciable extent for the benefit of his employer. We further stated:
“ ‘Acts of an employee for the benefit of third persons generally preclude the recovery of compensation for accidental injuries sustained during the performance of such acts, usually on the ground they are not incidental to any service which the employee is obligated to render under his contract of employment, and the injuries therefore cannot be said to arise out of and in the course of the employment. . . . However, where competent proof exists that the employee understood, or had reasonable grounds to believe that the act resulting in injury was incidental to his employment, or such as would prove beneficial to his employer’s interests or was encouraged by the employer in the performance of the act or similar acts for the purpose of creating a feeling of good will, or authorized so to do by common practice or custom, compensation may be recovered, since then a causal connection between the employment and the accident may be established.’ Schneider, 7 Workmen’s Compensation Text, sec. 1675.”
In Bellamy v. Manufacturing Co., 200 N.C. 676, 158 S.E. 246 (1931), the claimant, an employee in the spinning department, was required to remain in the mill for a half hour after work therein had stopped. During this period she was injured by accident while riding in an elevator to another floor of the *284mill for the purpose of seeing about getting her friend a job in the mill. Again, compensation was awarded.
In present case, the hearing commissioner and the Commission found as a fact that it was the custom with firemen of the Wilmington Fire Department to make minor repairs to their automobiles during their lunch break, that plaintiff’s superiors knew of this and made no objection, and that these repairs were to an appreciable extent a benefit to the fire department.
Article 25, Sec. LX11, of the Rules and Regulations of the Wilmington Fire Department, states that permission of the assistant chief on duty should be obtained 'before a fireman may repair his personal automobile. Plaintiff in this case did not obtain express permission of the assistant chief before attempting to clean his fellow employee’s oil breather cap. However, as Larson states:
“The most frequent ground for rejecting violation of rules as a defense, whether under the safety rule or wilful misconduct defense, is the lack of enforcement of the rule in practice. Habitual disregard of the rule has been made the basis of rejecting the defense in cases presenting such widely varied practices as . . . using gasoline for cleaning. . . .” 1A Larson, Workmen’s Compensation Law § 33.30 (1973).
In Parsons v. Swift & Co., 234 N.C. 580, 68 S.E. 2d 196 (1951), the deceased employee was employed to haul filler in a wheelbarrow at his employer’s fertilizer plant. He was killed while attempting to move a tractor on the employer’s premises. The employer had established a rule that no one should operate the tractors except those employees specifically directed to do so. The deceased was not specifically directed to drive the tractor. However, he had moved tractors under similar circumstances on previous occasions, as had other employees who were not specifically directed to operate tractors. We held the injury to be compensable even though the deceased had violated his employer’s rule. See Riddick v. Cedar Works, 227 N.C. 647, 43 S.E. 2d 850 (1947).
In present case, the Chief of the Wilmington Fire Department stated: “We allow a man to do minor things to his automobile — no big overhaul — and he is supposed to get permission *285to do anything of any degree. But to check his tires, check his oil, the battery or some minor thing during a lunch period, we don’t have any objection to him doing that.”
Captain Rhodes of the Wilmington Fire Department stated: “During the lunch hour firemen who are on duty, if they wish, are allowed to check their automobiles, but as far as doing any work on them they are not allowed to do any work on them. They are not allowed to do any major work. It would be all right to do some little incidental thing.” (Emphasis added.)
 In the case at bar there was competent evidence to support the hearing commissioner’s findings adopted by the Commission that plaintiff was required by his employer to remain at the fire station during his entire twenty-four-hour tour of duty, that firemen often made minor repairs to their automobiles on the fire station premises during their lunch hour, and that this practice was well known to and was allowed by plaintiff’s superiors. There was further competent evidence to support a finding that repairs of a minor nature to personal automobiles were to an appreciable extent a benefit to the fire department in that by keeping their automobiles in working condition the firemen could use them to report to duty when they were off duty in the event of an emergency, and also to support the finding that plaintiff sustained an injury by accident arising out of and in the course of his employment with the defendant employer on 18 October 1973. Such findings are conclusive on appeal. Lee v. Henderson & Associates, supra; Stubblefield v. Construction Co., supra; Henry v. Leather Co., 231 N.C. 477, 57 S.E. 2d 760 (1950): Brown v. Aluminum Co., 224 N.C. 766, 32 S.E. 2d 320 (1944).
We hold, therefore, that plaintiff’s act in assisting in the cleaning of the oil breather cap from a fellow employee’s car during the lunch period was a reasonable activity, and that the risk inherent in such activity was a risk of the employment. This reasonableness is attested by the fact that such practice was well known to plaintiff’s superiors who made no objection but, in fact, specifically allowed firemen to make such minor repairs during their lunch hour.
Other assignments of error have been considered and are without merit.
*286For the reasons stated, the decision of the Court of Appeals is affirmed.