Here is the PA state law in regards to triangle reflectors.
§ 4530. Portable emergency warning devices.
(a) General rule.--Every truck, other than a truck registered as either a Class I or Class II having a
gross weight of 7,000 pounds or less, truck tractor and bus and any motor vehicle towing a trailer shall
carry at least three portable emergency warning devices of a type specified by regulations promulgated by the department. The regulations shall be consistent with Motor Carrier Safety Regulations, Department of
Transportation, Federal Highway Administration, Bureau of Motor Carrier Safety, section 393.95.
(b) When display required.--Whenever any vehicle of a type referred to in subsection (a) is
disabled or stopped for more than ten minutes upon a roadway or shoulder outside of an urban district, or
upon any divided highway, the driver of the vehicle shall display the portable warning devices of the type
required under subsection (a) in such manner as the department shall direct by regulations.
Please note that all trucks over 7001 lbs MUST carry triangles. Also note that any vehicle towing a trailer must have triangles.
Here is the 1977 version.
§ 167.2. Scope and application.
Except for a truck registered as a Class I or Class II, every truck, truck tractor or bus, and every motor vehicle towing a trailer shall carry three portable emergency warning devices of a type specified in § 167.3 (relating to types of warning devices), which are consistent with 49 CFR 393.95 (relating to emergency equipment on all power units).
Authority
The provisions of this § 167.2 amended under the Vehicle Code, 75 Pa.C.S. § § 4103, 4530 and 6103.
Source
The provisions of this § 167.2 adopted October 21, 1977, effective October 22, 1977, 7 Pa.B. 3131; amended December 28, 1979, effective December 29, 1979, 9 Pa.B. 4275; amended March 18, 1988, effective March 19, 1988, 18 Pa.B. 1205. Immediately preceding text appears at serial page (56734).
Cross References
This section cited in 67 Pa. Code § 167.3 (relating to types of warning devices); and 67 Pa. Code § 167.8 (relating to display).
§ 167.3. Types of warning devices.
One of the following combinations of warning devices shall be carried on those vehicles, specified in § 167.2 (relating to scope and application), and equipped before January 1, 1974:
(1) Three liquid burning emergency flares which satisfy the requirements of SAE Standard J597, ‘‘Liquid Burning Emergency Flares’’, and three fusees and two red flags.
(2) Three electric emergency lanterns which satisfy the requirements of SAE Standard J596, ‘‘Electric Emergency Lanterns’’, and two red flags.
(3) Three red emergency reflectors and two red flags. A red emergency reflector shall conform to the following requirements:
Here is the requirement if you don't carry triangle flares. This is the federal law.
b)(2) Special rules —(i) Fusees and liquid-burning flares. The driver of a commercial motor vehicle equipped with only fusees or liquid-burning flares shall place a lighted fusee or liquid-burning flare at each of the locations specified in paragraph (b)(1) of this section. There shall be at least one lighted fusee or liquid-burning flare at each of the prescribed locations, as long as the commercial motor vehicle is stopped. Before the stopped commercial motor vehicle is moved, the driver shall extinguish and remove each fusee or liquid-burning flare.
(b)(2)(ii) Daylight hours. Except as provided in paragraph (b)(2)(iii) of this section, during the period lighted lamps are not required, three bidirectional reflective triangles, or three lighted fusees or liquid-burning flares shall be placed as specified in paragraph (b)(1) of this section within a time of 10 minutes. In the event the driver elects to use only fusees or liquid-burning flares in lieu of bidirectional reflective triangles or red flags, the driver must ensure that at least one fusee or liquid-burning flare remains lighted at each of the prescribed locations as long as the commercial motor vehicle is stopped or parked.
This is from 392.22 from the FMCSA. You are required to have enough fusse's for as long as you are stopped, IF you do not have triangles.
But I stand corrected as far as my previous statement of the mandatory 8 hrs in PA.
I also stand corrected as far as the requirements of the 10abc fire ex. I was too lazy to go to my truck and get the FMCSA Book. 10 abc is not precluded and I carry two in my truck and 1 in my trailer.
I will add more data to this post later.