bx wire

[sparkymarjon]

what is the purpose of thin wire inside of bx, is it to break up the eddie currents or is it a bonding wire

 

[roger]

It is only to assure continuity along the sheath for EGC purposes.

Roger

 

[jumper]

320.100 Construction. Type AC cable shall have an armor
of flexible metal tape and shall have an internal [COLOR="black"]bonding[/COLOR]
strip of copper or aluminum in intimate contact with the
armor for its entire length.

 

[hurk27]

what is the purpose of thin wire inside of bx, is it to break up the eddie currents or is it a bonding wire

It shorts out the turns in the sheath to lower the impedance path of the fault current back to source.

Also it is not required to be even terminated, as it can be just cut off when terminating the AC cable.

 

[muskrat]

what is the purpose of thin wire inside of bx, is it to break up the eddie currents or is it a bonding wire

"eddie currents"????
'splain that one for me please?

 

[sparkymarjon]

sorry i mean eddy currents not eddie current

sorry i mean eddy currents not eddie current

From Wikipedia, the free encyclopedia

Eddy currents (also called Foucault currents[1]) are currents induced in conductors, opposing the change in flux that generated them. It is caused when a conductor is exposed to a changing magnetic field due to relative motion of the field source and conductor; or due to variations of the field with time. This can cause a circulating flow of electrons, or a current, within the body of the conductor. These circulating eddies of current create induced magnetic fields that oppose the change of the original magnetic field due to Lenz's law, causing repulsive or drag forces between the conductor and the magnet. The stronger the applied magnetic field, or the greater the electrical conductivity of the conductor, or the faster the field that the conductor is exposed to changes, then the greater the currents that are developed and the greater the opposing field.
The term eddy current comes from analogous currents seen in water when dragging an oar breadthwise: localised areas of turbulence known as eddies give rise to persistent vortices.
Eddy currents, like all electric currents, generate heat as well as electromagnetic forces. The heat can be harnessed for induction heating. The electromagnetic forces can be used for levitation, creating movement, or to give a strong braking effect. Eddy currents can also have undesirable effects, for instance power loss in transformers. In this application, they are minimised with thin plates, by lamination of conductors or other details of conductor shape.
Self-induced eddy currents are responsible for the skin effect in conductors.[2] The latter can be used for non-destructive testing of materials for geometry features, like micro-cracks.[3] A similar effect is the proximity effect, which is caused by externally-induced eddy currents.[4]

 

[G._S._Ohm]

what is the purpose of thin wire inside of bx, is it to break up the eddie currents or is it a bonding wire

Eddy currents in BX @ 15 A or 20 A are probably negligible and the wire wouldn't do much to reduce them in any case, so. . .
the wire is a convenient way to connect to the BX shell?

 

[LarryFine]

what is the purpose of thin wire inside of bx, is it to break up the eddie currents or is it a bonding wire

It's to effectively short each turn of the spiral wrap to the next turn, so the sheath doesn't behave like an inductor during high-current ground faults.

 

[infinity]

It's to effectively short each turn of the spiral wrap to the next turn, so the sheath doesn't behave like an inductor during high-current ground faults.

Larry gave you a perfect simple text book answer.

 

[LarryFine]

Larry gave you a perfect simple text book answer.

I done good?

 

[hurk27]

I done good?

Yea my post 4 didn't even get a vote:grin:

 

[LarryFine]

Yea my post 4 didn't even get a vote:grin:

Awww. You can borrow mine.

 

[hurk27]

Awww. You can borrow mine.

Why thank you, I'll remember to return the favor if I ever get any:grin:

 

[roger]

Yea my post 4 didn't even get a vote:grin:

Don't feel bad Wayne, I said it in post #2 in different words and I didn't get a vote either.

Roger