Carbon Fiber as a conductor

[jimmyb514]

Hi there. Is carbon fiber's ability to conduct electricity wide spread common knowlage? I've been an aircraft mechanic for all of my adult life with composites starting to make inroads in the industry. I worked for a professional race team for 2 years, the car was at least 75% c/f not counting the engine, and c/f is ever growing in the boating industry. (although not on my cal21, she would faint). Anyway, I never knew how electrically conductive that stuff is untill we had a fire on an airplane. (on the ground, nobody injured) We later hooked up a lightbulb to a battery through it and it shown (?) beautifully. If someone wasn't aware of this property and they mounted devices on it, (switches etc....) they might be in for a rude shock, (pun intended). The fire was small and quick and it melted the glue enough to allow the piece of carbon fiber to be permenantly limp. bad news if it was structure. any thoughts? Thanks. I know my spelling stinks, sorry.

[JHJensen]

[quote=jimmyb514;422892]Hi there. Is carbon fiber's ability to conduct electricity wide spread common knowlage? I've been an aircraft mechanic for all of my adult life with composites starting to make inroads in the industry.(aircraft industry) QUOTE]

Jim,
To answer your question. Carbon fiber's ability to conduct electricity is quite well known in the marine industry and I believe amongst most owners of vessels using the material.

If they are not they should be because as you pointed out it can have some rather interesting results affecting the safety of the vessel or people in and around the vessel. The hazard list includes fire, shock and electrocution and corrosion of metals in contact with it and water.

Good for you for seeing and pointing out that carbon fiber is something to be aware of.

Best,

John J
ABYC Master Technician


For your information here is where it is considered in the industry and I am sure other standards mention it, but I had this handy.

Carbon fiber's ability to conduct electricity is mentioned in the ABYC Standards and Technical Reports:

ABYC Standard E-11 AC and DC Electrical Systems on Boats (page 14)

11.6.3.1.1.3 Metallic power inlets installed on metallic or carbon fiber reinforced boats using an isolation transformer or a galvanic isolator shall be insulated from metallic structure and components. On non-metallic boats using an isolation transformer or a galvanic isolator the power inlet shall be insulated from metallic components connected to the boat's ground.

ABYC Technical Educational Report TE-4 Lightning Protection

Carbon Fiber
Although partially conductive, carbon fiber materials, and carbon fiber masts, are regarded as non-conductive (nonmetallic) for the purpose of this technical information report. For lightning protection, carbon fiber masts require the addition of an air terminal and primary conductor as described elsewhere in this technical information report. If the hull or other structure contains carbon fiber, lightning conductors should be insulated from the laminate.

ABYC Standard E-2 Cathodic Protection
Carbon (Graphite)falls as the most noble material on the :

GALVANIC SERIES OF METALS IN SEA WATER WITH REFERENCE TO SILVER/SILVER CHLORIDE
REFERENCE CELL [Sea water flowing at 8 to 13 ft./sec.(except as noted), temperature range 50°F (10°C) to 80°F(26.7°C)]

(ANODIC OR LEAST NOBLE) CORROSION-POTENTIAL RANGE IN
MILLIVOLTS
Magnesium and Magnesium Alloys -1600 to –1630
Zinc -980 to –1030
Aluminum Alloys -760 to –1000
Cadmium -700 to –730
Mild Steel -600 to –710
Wrought Iron -600 to –710
Cast Iron -600 to –710
13% Chromium Stainless Steel, Type 410 (active in still water) -460 to –580
18-8 Stainless Steel, Type 304 (active in still water) -460 to –580
Ni-Resist -460 to –580
18-8, 3% Mo Stainless Steel, Type 316 (active in still water) -430 to –540
Inconel (78%Ni, 13.5%Cr, 6%Fe) (active in still water) -350 to -460
Aluminum Bronze (92% Cu, 8% Al) -310 to -420
Nibral (81.2% Cu, 4% Fe, 4.5% Ni, 9% Al, 1.3% Mg) -310 to –420
Naval Brass (60% Cu, 39% Zn) -300 to –400
Yellow Brass (65% Cu, 35% Zn) -300 to –400
Red Brass (85% Cu, 15% Zn) -300 to –400
Muntz Metal (60% Cu, 40% Zn) -300 to –400
Tin -310 to –330
Copper -300 to –570
50-50 Lead- Tin Solder -280 to –370
Admiralty Brass (71% Cu, 28% Zn, 1% Sn) -280 to –360
Aluminum Brass (76% Cu, 22% Zn, 2% Al) -280 to –360
Manganese Bronze (58.8% Cu,39%Zn,1%Sn, 1%Fe, 0.3%Mn) -270 to –340
Silicone Bronze (96% Cu Max, 0.80% Fe, 1.50%Zn, 2.00% Si,
0.75% Mn, 1.60% Sn)
-260 to –290
Bronze-Composition G (88% Cu, 2% Zn, 10% Sn) -240 to –310
Bronze ASTM B62 (thru-hull)(85%Cu, 5%Pb, 5%Sn, 5%Zn) -240 to –310
Bronze Composition M (88% Cu, 3% Zn, 6.5% Sn, 1.5% Pb) -240 to –310
13% Chromium Stainless Steel, Type 410 (passive) -260 to –350
Copper Nickel (90% Cu, 10% Ni) -210 to –280
Copper Nickel (75% Cu, 20% Ni, 5% Zn) -190 to –250
Lead -190 to –250
Copper Nickel (70% Cu, 30% Ni) -180 to –230
Inconell (78% Ni, 13.5% Cr, 6% Fe) (passive) -140 to –170
Nickel 200 -100 to –200
18-8 Stainless Steel, Type 304 (passive) -50 to –100
Monel 400, K-500 (70% Ni, 30% Cu) -40 to –140
Stainless Steel Propeller Shaft (ASTM 630:#17 & ASTM 564: #
19)
-30 to +130
18-8 Stainless Steel, Type 316 (passive) 3% Mo 0.0 to –100
Titanium -50 to +60
Hastelloy C -30 to +80
Stainless Steel Shafting (Bar) (UNS 20910) -250 to +60
Platimium +190 to +250
Graphite +200 to +300
(CATHODIC OR MOST NOBLE

[sck5]

My cousin's carbon fiber mast was struck by lightning - it had all the conductors, etc it was supposed to have but was still messed up enough to need replacement - the rest of the stuff on the boat was OK though. His insurance company must have taken a hell of a hit on that one.