Hard conduit for LS and Crit and Hospital Grade AC cable (and now MC)

[mshields]

Does anyone know when the NEC first strated requiring hard conduit for LS and Crit and the additional ground in AC cable for hospitals? Even if roughly?

 

[packersparky]

It looks to me like the raceway requirement for critical and life safety systems first appeared in the 1971 NEC. Not sure about the redundant ground.

 

[tortuga]

It looks to me like the raceway requirement for critical and life safety systems first appeared in the 1971 NEC. Not sure about the redundant ground.

The redundant ground started in 1971 also, however note that the 1971 NEC rewrote 517.

I believe in the 1930 NEC article 32 would have classified areas containing or dispensing 'Flammable Anesthetics' as a class I hazordus location, they did not have much power in operating rooms back then.
'Flamable Anesthetics' where first mentioned in the 1947 NEC as a example of a class 1 division 1 location under a FPN.
The 1951 NEC 5004(a) Class 1 division 1 section FPN mentions NFPA pamphlet 56 " a recommended safe practice for hospital operating rooms"
1953 Section 5135 'Combustible Anesthetics' is really the origin of 517 and was new to the 1953 NEC .
up to and including the 1968 edition 517 continued to be titled 'Flammable Anesthetics' which considered any room or space in which flammable anesthetics or volatile disinfecting agents are stored or dispensed a class 1 division 1 location. Operating rooms were largely limited to 8 volts between conductors, required to have isolation transformers etc.
Cheers

 

[mbrooke]

The redundant ground started in 1971 also, however note that the 1971 NEC rewrote 517.

I believe in the 1930 NEC article 32 would have classified areas containing or dispensing 'Flammable Anesthetics' as a class I hazordus location, they did not have much power in operating rooms back then.
'Flamable Anesthetics' where first mentioned in the 1947 NEC as a example of a class 1 division 1 location under a FPN.
The 1951 NEC 5004(a) Class 1 division 1 section FPN mentions NFPA pamphlet 56 " a recommended safe practice for hospital operating rooms"
1953 Section 5135 'Combustible Anesthetics' is really the origin of 517 and was new to the 1953 NEC .
up to and including the 1968 edition 517 continued to be titled 'Flammable Anesthetics' which considered any room or space in which flammable anesthetics or volatile disinfecting agents are stored or dispensed a class 1 division 1 location. Operating rooms were largely limited to 8 volts between conductors, required to have isolation transformers etc.
Cheers

8 volts between conductors? :blink:

 

[tortuga]

8 volts between conductors? :blink:

Flammable anesthetics were pretty common until the late 60's perhaps longer
and are what first motivated 517.
I dont know if they have been used in hospitals in decades but they are still considered class 1 div 1 in
what is now 517.60 in the 2017 NEC.
2017 NEC 517.61 (A)(6) Still mentions the 8 volts between conductors as an exemption from the requirements for extra hard usage cord and grounding.
From the 1968 NEC

517-1. Definitions.
(a) Flammable anesthetics are gases or vapors such as cyclopro.
pane, divinyl ether, ethyl chloride, ethyl ether, and ethylene, which
may form flammable or explosive mixtures with air, oxygen, or nitrous
oxide.
(b) For the purpose of this Article, anesthetizing locations are areas
in hospitals in which flammable anesthetics are or may be administered
to patients. Such locations will include operating rooms, delivery rooms
and anesthesia rooms, and will also include any corridors, utility rooms
or other areas which are or may be used for administering flammable
anesthetics to patients. Recovery rooms are not classed as anesthetizing
locations unless used for administering flammable anesthetics.

and

517-2. Hazardous Areas.
(a) Any room or space in which flammable anesthetics or volatile
flammable disinfecting agents are stored shall be considered to be a
Class I, Division 1 location throughout.
(b) In an anesthetizing location as defined in Section 517-1, the en-
tire area shall be considered to be a Class I, Division 1 location which
shall extend upward to a level 5 feet above the floor.
shall extend upward to a level 5 feet above the floor.
517-3. Wiring and Equipment Within Hazardous Areas.
(a) In hazardous areas as defined in Section 517-2, all fixed wiring
and equipment, and all portable equipment, including lamps and other
utilization equipment, operating at more than 8 volts between conduc-
tors, shall conform to the requirements of Sections 501-1 to 501-15 in-
clusive and of Sections 501-16(a and b) for Class I, Division 1 loca-
tions, and all such equipment shall be specifically approved for the
hazardous atmospheres involved.
(b) Where a box, fitting or enclosure is partially but not entirely
within a hazardous area, the hazardous area shall be considered to be
extended to include the entire box, fitting or enclosure.
(c) Flexible cords which are or may be used in hazardous areas for
connection to portable utilization equipment, including lamps operat-
ing at more than 8 volts between conductors shall be of a type ap-
proved for extra hard usage, shall be of ample length, and shall include
an additional conductor for grounding. A storage device for the flexi-
ble cord shall be provided, and shall not subject the cord to bending at
a radius of less than 3 inches.
(d) Receptacles and attachment plugs shall be of the type with pro-
vision for connection of the grounding conductor, and where located
within a hazardous area, shall be approved for Class I location. Single
phase, 125 volt receptacles and attachment plugs shall be of the type
recognized in Section 2438 of NFPA Code for the Use of Flammable
anesthetics (No. 56).

I dont know what that 8 volt equipment would have been but it was in the code for the 50's and 60's as the exemption from allot of explosion proof wiring so I bed they had something.
--Cheers

 

[retirede]

Flammable anesthetics were pretty common until the late 60's perhaps longer
and are what first motivated 517.
--Cheers

I was a technician in a hospital in 1975. We had to conductivity test the floors in every operating room monthly. It was to ensure no static could build up and cause a spark to ignite the anesthetic. So it was still in use then.