Aluminum Conduit

[bob]

I seldom see AL conduit spec or discussed in this forum. Conduit is allowed to be used as an EGC.
However due to the iron in GRC or EMT or equal
the the magnetic field arising from the fault current increases the impedance of the conduit
thus limiting the lenght of the run. However the AL is not effected in the same way since it has no iron. The length of the run can be much greater and still provide a good EGC. Under what conditions other than in concrete or underground would AL conduit not be used? This subject is covered very well in the Soares Book on Grounding.

[pierre]

I don't know why, maybe cost, the only time I was involved installing aluminum conduit was when I was an apprentice and we were wiring 400 hz computers.

Pierre

[bennie]

The impedance of the fault path needs to be of a value to assure operation of overcurrent devices.

Any fault current more than needed is called "meltdown".

The impedance of conduit is variable in direct proportion to intensity of current.

Magnetic fields do not affect aluminum, but aluminum does not affect magnetic fields either.

[pwhitton]

You have to use Al in healthcare facilities in MRI rooms. Obviously due to the magnetic field of the MRI machine.

FYI: Bennie I try to be read this forum but with a newborn, new house and work..... let's just say days are short