United States Patent (19)
`Gingue et al.
`
`54 FLAME RETARDANT AND SMOKE
`SUPPRESSANT COMPOSTEELECTRICAL
`INSULATION, INSULATED ELECTRICAL
`CONDUCTORS AND JACKETED PLENUM
`CABLE FORMED THEREFROM
`
`75) Inventors: Robert N. Gingue, Westminster;
`Charles A. Glew, Framingham;
`Anthony E. Sansone, Leominster;
`Homaira K. Naseem, Boylston, all of
`Mass.
`(73) Assignee: AlphaGary Corporation, Leominster,
`Mass.
`
`(21) Appl. No.: 389,214
`22 Filed:
`Feb. 15, 1995
`(51) Int. Cl. ................... HO1B 7/28
`52 U.S. Cl. ................................. 174/120 R; 174/121A:
`174/113 R
`58 Field of Search ........................ 174/110 R, 110 PM,
`174/110 F, 110 V, 120 R, 120 SR, 121 A,
`113 R
`
`56
`
`References Cited .
`U.S. PATENT DOCUMENTS
`... 174/110
`3,064,073 11/1962 Downing et al. ...
`29/202.5
`3,529,340 9/1970 Polizzano et al.
`3,567,846 3/1971 Brorein ................................. 174/102
`3,930,984 1/1976 Pitchford ..........
`... 208/10 X
`4,104,481
`8/1978 Wilkenloh et al. ....................... 174/28
`4,107,354 8/1978 Wilkenloh et al. ..................... 427,118
`4,204,086 5/1980 Suzuki ................................ 174/102 R
`4,255,318 3/1981 Kaide et al. .
`... 260/42.18 X
`4274,997 6/1981 Schneider et al.
`... 260/45.75 X
`4,234,842
`8/1981 Arroyo et al. .......................... 174/107
`4,319,940 3/1982 Arroyo et al. ............................ 156/56
`4,352,701 10/1982 Shimba et al. ............................ 156/51
`4,412,094 10/1983 Dougherty et al.
`... 174/10 F
`4,468,089 8/1984 Brorein ............
`... 350/96.23
`4,468,435 8/1984 Shimba et al. .......................... 428/383
`4,562,302 12/1985 Checkland et al.
`... 174/118
`4,789,589 12/1988 Baxter .................................. 428/317.5
`
`
`
`US005670748A
`Patent Number:
`11
`45 Date of Patent:
`
`5,670,748
`Sep. 23, 1997
`
`1/1990 Naseem ................................... 252,609
`4,892,683
`4,963,609 10/1990 Anderson et al.
`... 524/413
`4,983,326
`1/1991 Wandersall ...........
`... 252/603 X
`5,036,121
`7/1991 Coaker et al. ..
`... 524/100X
`5,059,651 10/1991 Ueno ...............
`... 524/424X
`5,104,735 4/1992 Ciofi et al. .....
`... 428/383 X
`5,158,999 10/1992 Swales et al. ...................... 524/100X
`5,164,258 11/1992 Shida et al. ...................... 428/319.3 X
`5,173,960 12/1992 Dickinson .......
`... 38.5/100X
`5,358,786 10/1994 Ishikawa et al. ................... 428/380 X
`FOREIGN PATENT DOCUMENTS
`2156229 5/1973 France.
`2220549 10/1974 France.
`3409369 9/1985 Germany ........................... 174/110 F
`47-94.99 3/1972 Japan ................................. 174/110 F
`21252.07 2/1984 United Kingdom.
`Primary Examiner-Hyung S. Sough
`Assistant Examiner-Chau N. Nguyen
`Attorney, Agent, or Firm-McAndrews, Held & Malloy,
`Ltd.
`ABSTRACT
`57
`A flame retardant and smoke suppressant electrical insula
`tion composition for an electrical conductor comprises an
`inner layer and an outer layer. The inner layer, which
`contacts and surrounds the conductor, comprises a foamed
`polymeric material selected from the group consisting of
`polyolefins and polyurethane. The outer layer, which con
`tacts and surrounds the inner layer, comprises a halogenated
`polymeric material and at least one outer layer additive to
`render the outer layer flame retardant and smoke suppres
`sant. A flame retardant and smoke suppressant insulated
`electrical conductor comprises a length of electrically con
`ductive material surrounded by the insulation composition.
`Aflame retardant and Smoke suppressantjacketed electrical
`cable comprises a plurality of insulated electrical conduc
`tors. An outer jacket, which substantially surrounds the
`insulated electrical conductors, comprises a halogenated
`polymeric material and at least one outer jacket additive to
`render the outer jacket flame retardant and smoke suppres
`Sant.
`
`3 Claims, 1 Drawing Sheet
`
`

`

`U.S. Patent
`
`
`
`Sep. 23, 1997
`
`5,670,748
`
`U.S. Patent
`
`Sep. 23, 1997
`
`5,670,748
`
`
`
`
`CommSc ope Exhibit 1027
`
`U.S. Patent
`
`Sep. 23, 1997
`
`5,670,748
`
`
`
`
`U.S. Patent
`
`Sep. 23, 1997
`
`5,670,748
`
`
`
`
`

`

`5,670,748
`
`10
`
`5
`
`20
`
`25
`
`2
`In plenum applications for voice and data transmission,
`electrical conductors and cables should exhibit low Smoke
`evolution, low flame spread, and favorable electrical prop
`erties. Materials are generally selected for plenum applica
`tions such that they exhibit a balance of favorable and
`unfavorable properties. In this regard, each commonly
`employed material has a unique combination of desirable
`characteristics and practical limitations. Without regard to
`flame retardancy and smoke suppressant characteristics,
`olefin polymers, such as polyethylene and polypropylene,
`are melt extrudable thermoplastic materials having favor
`able electrical properties as manifested by their very low
`dielectric constant and low dissipation factor.
`Dielectric constant is the property of an insulation mate
`rial which determines the amount of electrostatic energy
`stored per unit potential gradient. Dielectric constant is
`normally expressed as a ratio. The dielectric constant of air
`is 1.0, while the dielectric constant for polyethylene is 2.2.
`Thus, the capacitance of polyethylene is 2.2 times that of air.
`Dielectric constant is also referred to as the Specific Induc
`tive Capacity or Pesmitivity.
`Dissipation factor refers to the energy lost when voltage
`is applied across an insulation material, and is the cotangent
`of the phase angle between voltage and current in a reactive
`component. Dissipation factor is quite sensitive to contami
`nation of an insulation material. Dissipation factor is also
`referred to as the Power Factor (of dielectrics).
`Fluorinated ethylene/propylene polymers exhibit electri
`cal performance comparable to non-halogenated to olefin
`polymers, such as polyethylene, but are over 15 times more
`expensive per pound. Polyethylene also has favorable
`mechanical properties as a cable jacket as manifested by its
`tensile strength and elongation to break. However, polyeth
`ylene exhibits unfavorable flame and smoke characteristics.
`Limiting Oxygen Index (ASTM D-2863) ("LOI) is a test
`method for determining the percent concentration of oxygen
`that will support flaming combustion of a test material. The
`greater the LOI, the less susceptible a material is to burning.
`In the atmosphere, there is approximately 21% oxygen, and
`therefore a material exhibiting an LOI of 22% or more
`cannot burn under ambient conditions. As pure polymers
`without flame retardant additives, members of the olefin
`family, namely, polyethylene and polypropylene, have an
`LOI of approximately 19. Because their LOI is less than 21,
`these olefins exhibit disadvantageous properties relative to
`flame retardancy in that they do not self-extinguish flame,
`but propagate flame with a high rate of heat release.
`Moreover, the burning melt drips on the surrounding areas,
`thereby further propagating the flame.
`Table 1 below summarizes the electrical performance and
`flame retardancy characteristics of several polymeric mate
`rials. Besides fluorinated ethylene/propylene, other melt
`extrudable thermoplastic generally do not provide a favor
`able balance of properties (i.e., high LOL, low dielectric
`constant, and low dissipation factor). Moreover, when flame
`retardant and Smoke suppressant additives are included
`within thermoplastic materials, the overall electrical prop
`erties generally deteriorate.
`
`1.
`FLAME RETARDANT AND SMOKE
`SUPPRESSANT COMPOSITE ELECTRICAL
`INSULATION, INSULATED ELECTRICAL
`CONDUCTORS AND JACKETED PLENUM
`CABLE FORMED THEREFROM
`FIELD OF THE INVENTION
`The present invention relates to insulated electrical con
`ductors and jacketed electrical cables. More particularly, the
`present invention relates to composite electrical insulation
`exhibiting reduced flame spread, reduced smoke evolution,
`and favorable electrical properties. The present invention
`also relates to insulated electrical conductors and jacketed
`plenum cable formed from the flame retardant and smoke
`Suppressant composite insulation.
`BACKGROUND OF THE INVENTION
`A broad range of electrical conductors and electrical
`cables are installed in modern buildings for a wide variety of
`uses. Such uses include data transmission between
`computers, voice communications, as well as control signal
`transmission for building security, fire alarm, and tempera
`ture control systems. These cable networks extend through
`out modern office and industrial buildings, and frequently
`extend through the space between the dropped ceiling and
`the floor above. Ventilation system components are also
`frequently extended through this space for directing heated
`and chilled air to the space below the ceiling and also to
`direct return air exchange. The space between the dropped
`ceiling and the floor above is commonly referred to as the
`plenum area. Electrical conductors and cables extending
`through plenum areas are governed by special provisions of
`the National Electric Code (“NEC").
`Because of concerns that flame and smoke could travel
`along the extent of a plenum area in the event the electrical
`conductors and cable were involved in a fire, the National
`Fire Protection Association ("NFPA") has developed a stan
`dard to reduce the amount of flammable material incorpo
`rated into insulated electrical conductors and jacketed
`cables. Reducing the amount of flammable material would,
`according to the NFPA, diminish the potential of the insu
`lating and jacket materials from spreading flames and evolv
`ing smoke to adjacent plenum areas and potentially to more
`distant and widespread areas throughout a building.
`In 1975, the NFPA recognized the potential flame and
`Smoke hazards created by burning cables in plenum areas,
`and adopted in the NEC a standard for flame retardant and
`Smoke Suppressant cables. This standard, commonly
`referred to as "the Plenum Cable Standard”, permits the use
`of cable without conduit, so long as the cable exhibits low
`Smoke and flame retardant characteristics. The test method
`for measuring these characteristics is commonly referred to
`as the Steiner Tunnel Test. The Steiner Tunnel Test has been
`adapted for the burning of cables according to the following
`test protocols: NFPA 262, Underwriters Laboratories (U.L.)
`910, or Canadian Standards Association (CSA) FT-6. The
`test conditions for each of the U.L. 910 Steiner Tunnel Test,
`CSA FT-6, and NFPA 262 are as follows: a 300,000 BTU/
`hour flame is applied for 20 minutes to ten 24-foot lengths
`of test cables mounted on a horizontal tray within a tunnel.
`The criteria for passing the Steiner Tunnel Test are as
`follows:
`A. Flame spread-flame travel less than 5.0 feet.
`B. Smoke generation:
`1. Maximum optical density of Smoke less than 0.5.
`2. Average optical density of smoke less than 0.15.
`
`30
`
`35
`
`45
`
`50
`
`55
`
`TABLE 1.
`
`65
`
`Electrical
`Properties
`
`Fire Retardancy
`Characteristics
`
`NBS Smoke
`Values Optical
`Density, DMC
`
`

`

`3
`
`5,670,748
`
`Non
`Dissipation
`Dielectric
`LOI Flaming Flaming
`Factor
`Constant
`1 MHz, 23° C. 1 MHz, 23° C. % Mode Mode
`
`2.2
`2.6-3.0
`2.1
`2.73.5
`3.2-3.6
`3.5-3.8
`
`00006-00O2
`.003-037
`OOO55
`.024.07.0
`.018-080
`,038-080
`
`19
`28-32
`>80
`32
`39
`. 49
`
`387
`---
`
`740
`200
`a200
`
`719
`m
`-
`280
`190
`<170
`
`Material
`
`PE
`FRPE
`FEP
`PVC
`RSFRPVC
`LSFRPVC
`
`O
`
`35
`
`UL/CSA
`Designation
`
`CMP/MPP
`
`CMR/MPR
`
`CMGMPG
`
`CM/MP
`
`TABLE 2
`
`Cable Fire Test
`
`Flame Energy
`
`Plenum U.L. 90
`CSAFT-6
`Horizontal
`Riser
`UL. 1666
`Wertical
`FTL4
`Wertical
`IEEE 1581
`Wertical
`
`300,000 BTU/hour
`
`527,000 BTU/hour
`
`70,000 BTU/hour
`Burner angle 20
`70,000 BTU/hour
`Burner angle O
`
`45
`
`50
`
`55
`
`The principal electrical criteria can be satisfied based
`upon the dielectric constant and dissipation factor of an
`insulation or jacketing material. Secondarily, the electrical
`criteria can be satisfied by certain aspects of the cable design
`such as, for example, the insulated twisted pair lay lengths.
`Lay length, as it pertains to wire and cable, is the axial
`distance required for one cabled conductor or conductor
`strand to complete one revolution about the axis of the cable.
`Tighter and/or shorter lay lengths generally improve elec
`trical properties.
`
`65
`
`20
`
`25
`
`In the above table, PE designates polyethylene, FRPE des
`ignates polyethylene with flame retardant additives, FEP
`designates fluorinated ethylene/propylene polymer, PVC
`designates polyvinylchloride, RSFRPVC designates
`reduced smoke flame retardant polyvinylchloride, LSFR
`15
`PVC designates low smoke flame retardant
`polyvinylchloride. LOI designates Limiting Oxygen Index,
`NBS designates the National Bureau of Standards, and
`DMC designates Maximum Optical Density Corrected.
`In general, the electrical performance of an insulating
`material is enhanced by foaming or expanding the corre
`sponding solid material. Foaming also decreases the amount
`of flammable material employed for a given volume of
`material. Accordingly, a foamed material is preferably
`employed to achieve a favorable balance of electrical prop
`erties and flame retardancy.
`In addition to the requirement of low smoke evolution and
`flame spread for plenum applications, there is a growing
`need for enhanced electrical properties for the transmission
`of voice and data over twisted pair cables. In this regard,
`standards for electrical performance of twisted pair cables
`are set forth in Electronic Industry Association/
`Telecommunications Industry Association (EIA/TIA) docu
`ment TSB 36 and 40. The standards include criteria for
`attenuation, impedance, crosstalk, and conductor resistance.
`In the U.S. and Canada, the standards for flame retardancy
`for voice communication and data communication cables are
`stringent. The plenum cable test (U.L. 910/CSA FT-6) and
`riser cable test U.L. 1666 are significantly more stringent
`than the predominantly used International fire test IEC
`332-3, which is similar to the IEEE 383/U.L. 1581 test.
`Table 2 below summarizes the standards required for various
`U.L. and CSA cable designations:
`
`4
`SUMMARY OF THE INVENTION
`The present cable design incorporates an inner layer
`comprising afoamed or expanded polyolefin material and an
`outer layer comprising a halogenated polymeric material.
`This composite insulation provides a heterogeneous core
`that optimizes the electrical characteristics (i.e., the dielec
`tric constant and dissipation factor) of the material of the
`inner layer in direct contact with the copper conductor, while
`adding an outer layer over this substrate that incorporates the
`desired properties of intumescent char and flame retardancy.
`Intumescence refers to the foaming or swelling of a plastic
`or other material when exposed to high surface temperatures
`or flames. Thus, intumescent char is a foamed or swelled
`char.
`A single conductor can be mated in a pair or quad
`configuration of various numbers of conductors to form a
`cable. The predominant cable construction is a 4-pair core.
`This typical 4-pair composite insulated core is then jacketed
`with a halogenated low smoke and flame retardant material
`for plenum cable applications.
`The preferred insulation composition comprises:
`(a) an inner layer comprising afoamed polymeric material
`selected from the group consisting of polyolefins and
`polyurethane, the inner layer contacting and surround
`ing the conductor; and
`(b) an outer layer comprising a halogenated polymeric
`material and at least one outer layer additive, the outer
`layer contacting and Surrounding the inner layer, the at
`least one outer layer additive rendering the outer layer
`flame retardant and Smoke suppressant.
`The preferred foamed inner layer polymeric material
`comprises foamed polyethylene or foamed polypropylene.
`Foamed polyurethane could also be employed, as well as
`silicone polymers such as hexamethyldisiloxane,
`octamethyltrisiloxane, deca methyltetrasiloxane.
`The inner layer preferably further comprises at least one
`inner layer additive, the at least inner layer additive render
`ing the inner layer flame retardant and smoke suppressant.
`The at least one inner layer additive is preferably selected
`from the group consisting of magnesium complexes, molyb
`date complexes, phosphate complexes, alumina trihydrate,
`and Zinc borate.
`The most preferred inner layer additive is magnesium
`hydroxide, which simultaneously renders the inner layer
`both flame retardant and smoke suppressant. Separate inner
`layer additives could also be employed for flame retardancy
`and for smoke suppression.
`The preferred molybdate complexes comprise molybde
`num oxide and zinc molybdate. The preferred phosphate
`complexes comprise ammonium polyphosphate and
`melamine phosphate.
`The preferred halogenated polymeric material is selected
`from the group consisting of polyvinylchloride (PVC), poly
`vinyladinechloride (PVDC), polyvinyladinefluoride
`(PVDF), and ethylchlorotetrafluoroethylene (ECTFE).
`The at least one outer layer additive is selected from the
`group consisting of antimony trioxide,
`decabromodiphenyloxide, brominated dioctylphthalate, bro
`minated diisooctylphthalate, decachlorodiphenyloxide,
`chlorinated dioctylphthalate, chlorinated
`disooctylphthalate, magnesium complexes, molybdate
`complexes, phosphate complexes, alumina trihydrate, and
`zinc borate. The most preferred outer layer additive is the
`combination of antimony trioxide and at least one of
`decachlorodiphenyloxide, chlorinated dioctylphthalate, and
`chlorinated diisooctylphthalate.
`
`

`

`5,670,748
`
`-continued
`
`Ingredient
`
`Parts by
`weight
`
`O
`
`15
`
`stabilizer
`Silicone based low-density
`polyethylene
`Azodicarbonamide
`Zinc stearate
`The preferred formulation for
`the foamed inner layer material formed by gas injection is as follows:
`Ethylene-methylmethacrylate copolymer
`75-125
`Silane grafted polyethylene
`8-28
`Maleic acid derivative of ethylenef
`2-8
`x-olefin copolymer
`Ethylene-methylmethacrylate maleic
`0.5-5
`anhydride copolymer
`Magnesium hydroxide
`Tetrakis (methylene 3,5-di-tert-butyl-
`4-hydroxyhydrocinnamate methane)
`Polymeric hindered amine light
`stabilizer
`Silicone based low-density
`polyethylene
`The preferred formulation for
`the outer layer halogenated material is as follows:
`Homopolymer PVC Resin
`(electrical grade)
`Hindered phenolic antioxidant
`Antimony trioxide
`Tribasic lead sulphate
`Dibasic lead stearate
`Barium/zinc stabilizer complex
`Magnesium hydroxide
`Molybdate complex
`Permanent plasticizer
`Stearic acid
`Brominated aromatic ester
`Alkyl aryl phosphate ester
`Pentaerythritol
`Aluminum trihydrate
`
`2-10
`
`2-7
`0.3-0.8
`
`120-190
`0.15-1
`
`0.1-0.6
`
`2-10
`
`100
`
`0.1-0.5
`0.5-2.5
`5-15
`0.1-0.3
`0.5-3.0
`5-15
`15-35
`10-30
`0.1-0.8
`23-35
`2-12
`2-2
`30-70
`
`S
`BRIEF DESCRIPTION OF THE DRAWTNGS
`FIG. 1 is a sectional view of an insulated electrical
`conductor comprising a centrally disposed electrical
`conductor, a foamed polymeric inner layer surrounding the
`central conductor, and an outer layer comprising a haloge
`nated polymeric material and at least one flame retardant and
`Smoke suppressant additive.
`FIG. 2 is a sectional view of a 4-pair jacketed electrical
`cable for plenum applications comprising a plurality of
`insulated electrical conductors and an outer jacket compris
`ing a halogenated polymeric material and at least one flame
`retardant and smoke suppressant additive.
`
`DETALED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`The present composite insulation, insulated electrical
`conductors, and jacketed plenum cable construction exhibit
`favorable electrical properties for data transmission cables,
`while also exhibiting favorable flame retardancy and smoke
`suppressant characteristics to satisfy the UL 910 Steiner
`Tunnel Test.
`A. Conductor and Insulation
`Turning first to FIG. 1, an insulated electrical conductor
`25
`10 comprises a centrally disposed electrical conductor 12. A
`foamed polymeric inner layer 14 surrounds the central
`conductor 12. An outer layer 16 comprising a halogenated
`polymeric material and at least one flame retardant and
`Smoke suppressant additive surrounds the inner layer 14.
`30
`Twisted pair cables predominantly employ 22-, 24- and
`26-gauge copper and silver conductors. The conductors may
`be solid or stranded. For 24-gauge copper conductors, the
`wall thickness of conventional insulation may vary from
`approximately 0.005 to approximately 0.009 inches. The
`inner layer of the present composite insulation material,
`which is in contact with and surrounds the conductor, is
`preferably a foamed or expanded olefin polymer with an
`optional flame retardant additive. The inner layer materialis
`foamed by gas injection using, for example, nitrogen. The
`40
`inner layer material may also be foamed by addition of a
`chemical blowing agent such as, for example,
`aZodicarbonamide, which can be incorporated or blended
`into the inner layer material prior to extrusion.
`Typically, the foamed inner layer material extruded over
`the copper conductor is expanded from approximately
`20-60%, with a final thickness of approximately
`0.004-0.007 inches. In coextrusion, tandem extrusion, or
`two-pass extrusion, a skin of flame retardant halogenated
`material is applied as an outer layer over the foamed material
`in a thickness of approximately 0.002-0.004 inches.
`The preferred formulation for the foamed inner layer
`material formed with the chemical blowing agent is as
`follows:
`
`35
`
`45
`
`50
`
`55
`
`The above heterogeneous composite permits the use of an
`insulation material having favorable dielectric properties in
`contact with the copper conductor, while employing a flame
`retardent skin to mitigate flame propagation of the foamed
`material.
`B. Jacketing Material Over Paired Conductors
`Turning next to FIG. 2, a jacketed electrical cable 20 for
`plenum applications comprises 4 pairs of insulated electrical
`conductors, one pair of which is designated in FIG. 2 as
`insulated conductors 22. As shown in FIG. 2, each of
`insulated electrical conductors 22 comprises a centrally
`disposed electrical conductor 24, a foamed polymeric inner
`layer 26 surrounding the central conductor 24, and an outer
`layer 28 comprising a halogenated polymeric material and at
`least one flame retardant and smoke suppressant additive.
`An outer jacket 30 comprising a halogenated polymeric
`material and at least one flame retardant and smoke sup
`pressant additive surrounds the 4 pairs of electrical conduc
`tors.
`In the overall cable design, the foamed, skinned insulated
`conductors are paired together. Four paired cables represent
`the predominant application for the use of foamed, skinned
`insulated materials, although a different number of pairs
`(from 2 to 200 and greater) may also be employed. The
`foamed, skinned paired insulated conductors (for example,
`4-pair cables) is then jacketed with a halogenated material.
`On a typical 4-pair cable, the jacket is approximately
`0.0135-0.020 inches in thickness.
`The preferred formulation for the halogenated jacketing
`material is as follows is substantially identical in terms of
`ingredients and parts by weight to the preferred formulation
`for the outer layer halogenated material set forth above.
`
`Ingredient
`Ethylene-methylmethacrylate copolymer
`Silane grafted polyethylene
`Maleic acid derivative of ethylene/
`x-olefin copolymer
`Ethylene-methylmethacrylate maleic
`anhydride copolymer
`Magnesium hydroxide
`Tetrakis (methylene 3,5-di-tert-butyl-
`4-hydroxyhydrocinnamate methane)
`Polymeric hindered amine light
`
`Parts by
`weight
`75-125
`8-28
`2-8
`0.5-5
`
`120-190
`0.15-1
`
`0.1-0.6
`
`65
`
`

`

`5,670,748
`
`5
`
`10
`
`15
`
`20
`
`7
`While particular elements, embodiments and applications
`of the present invention have been shown and described, it
`will be understood, of course, that the invention is not
`limited thereto since modifications may be made by those
`skilled in the art, particularly in light of the foregoing
`teachings. It is therefore contemplated by the appended
`claims to cover such modifications as incorporate those
`features which come within the spirit and scope of the
`invention.
`What is claimed is:
`1. A flame retardant and Smoke suppressant insulation
`composition for an electrical conductor, the composition
`comprising:
`(a) an inner layer comprising a foamed polymeric material
`selected from the group consisting of polyolefins and
`polyurethane, said inner layer contacting and surround
`ing the conductor; and
`(b) an outer layer comprising a halogenated polymeric
`material and at least one outer layer additive, said outer
`layer contacting and surrounding said inner layer, said
`at least one outer layer additive rendering said outer
`layer flame retardant and smoke suppressant;
`wherein said at least one outer layer additive is antimony
`trioxide and at least one of decachlorodiphenyloxide, chlo
`rinated dioctylphthalate, and chlorinated diisooctylphtha
`late.
`2. A flame retardant and smoke suppressant insulated
`electrical conductor comprising:
`(a) a length of electrically conductive material;
`(b) an inner layer comprising a foamed polymeric mate
`rial selected from the group consisting of polyolefins
`and polyurethane, said inner layer contacting and sur
`rounding said length of electrically conductive mate
`rial; and
`
`25
`
`30
`
`8
`(c) an outer layer comprising a halogenated polymeric
`material and at least one outer layer additive, said outer
`layer contacting and surrounding said inner layer, said
`at least one outer layer additive rendering said outer
`layer flame retardant and smoke suppressants;
`wherein said at least one outer layer additive is antimony
`trioxide and at least one of decachlorodiphenyloxide, chlo
`rinated dioctylphthalate, and chlorinated diisooctylphtha
`late.
`3. A flame retardant and smoke suppressant jacketed
`electrical cable comprising:
`(a) a plurality of insulated electrical conductors, at least
`one of said insulated electrical conductors comprising:
`(1) a length of electrically conductive material;
`(2) a first layer comprising a foamed polymeric mate
`rial selected from the group consisting of polyolefins
`and polyurethane, said first layer contacting and
`surrounding said length of electrically conductive
`materials; and
`(3) a second layer comprising a first halogenated poly
`meric material and at least one second layer additive,
`said second layer contacting and surrounding said
`first layer, said at least one second layer additive
`rendering said second layer flame retardant and
`Smoke Suppressant; and
`(b) an outer jacket comprising a second halogenated
`polymeric material and at least one outer jacket
`additive, said outer jacket substantially surrounding
`said plurality of insulated electrical conductors;
`wherein said at least one second layer additive is antimony
`trioxide and at least one of decachlorodiphenyloxide, chlo
`rinated dioctylphthalate, and chlorinated diisooctylphtha
`late.
`
`