Magnetic vs. non-magnetic EMT

[ish1284]

Hello I'm having trouble determining whether to model EMT as magnetic or non-magnetic in short circuit calculations as I know this will have an impact on an overall cable's impedance.

Is the majority of EMT out there magnetic rather than non magnetic or vice versa? Does the conduit being rigid or not play a role? Most of the time in the feeder schedules I am given show whether it's PVC or EMT and if it's rigid or not. Any tricks for how to make a sound assumption based on that information? Your help would be appreciated. Thanks!

 

[Dennis Alwon]

Welcome to the forum

All the emt I have seen is magnetic.

 

[ggunn]

Welcome to the forum

All the emt I have seen is magnetic.

Isn't there aluminum EMT?

 

[dkidd]

Isn't there aluminum EMT?

Yes

http://www.americanconduit.com/products/aluminum-electrical-metallic-tubing-emt.html

 

[K8MHZ]

Isn't there aluminum EMT?

Yes.

http://www.americanconduit.com/products/aluminum-electrical-metallic-tubing-emt.html

 

[ggunn]

Yes.

http://www.americanconduit.com/products/aluminum-electrical-metallic-tubing-emt.html

Well then, unless you have an aluminum magnet...

 

[zbang]

Is the majority of EMT out there magnetic rather than non magnetic or vice versa?

Assume that EMT will be regular steel, and thus magnetic. Stainless-steel and aluminum EMT do exist, but they would be called out in a spec.

Does the conduit being rigid or not play a role?

No, only the metal composition.

 

[Dennis Alwon]

Isn't there aluminum EMT?

Yes, there is but that is not a standard install.

 

[ron]

We typically model raceway as non-magnetic unless we know for sure it is magnetic.

Non-magnetic will provide worst case short circuit values. Arc Flash incident energies might end up not be worst case (higher fault current makes OCPDs open faster, thus sometimes lower level PPE called out), but you need to pick your poison.