Aluminum Conduit

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cvirgil467

Senior Member
Location
NewYork
Using aluminum rigid conduit that is carrying a few single phase circuits from a dimmer control panel to light fixtures. The aluminum conduit passes by some audio equipment.

Is there an issue with the non-ferrous aluminum conduit not able to act as a shield for the EMI from the branch circuit conductors inside of the aluminum conduit?

Thanks.
b
 

GoldDigger

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Location
Placerville, CA, USA
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Retired PV System Designer
The aluminum conduit will do a fine job of shielding against electric field changes, which will be large for an unfiltered dimmer output.
Even a ferrous metal will not be particularly good at shielding magnetic field changes. For that the single most effective thing you can do will be to twist the hot wires with their corresponding neutral (or switch leg).
 

Fulthrotl

~Autocorrect is My Worst Enema.~
The aluminum conduit will do a fine job of shielding against electric field changes, which will be large for an unfiltered dimmer output.
Even a ferrous metal will not be particularly good at shielding magnetic field changes. For that the single most effective thing you can do will be to twist the hot wires with their corresponding neutral (or switch leg).

yep... UTP works fine for that.... i use cat 6, and if i have a heavy load, i
parallel them..... sometimes they get a little warm, it seems...
but no noise at all.....

learned this trick from a TI guy who underbids EVERYBODY....
 

GoldDigger

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Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
yep... UTP works fine for that.... i use cat 6, and if i have a heavy load, i
parallel them..... sometimes they get a little warm, it seems...
but no noise at all.....

learned this trick from a TI guy who underbids EVERYBODY....
My only concern is whether the OP is talking about dimmer control input or dimmer module output. For the latter, CAT will not work!
 

cvirgil467

Senior Member
Location
NewYork
Thanks.

The wiring within the aluminum conduit will be 120v with single phase circuits. Each single phase circuit will have a dedicated neutral, not shared. It was my understanding that since the conduit is non-ferrous it would not provide any shielding from emi radiating from the single phase circuits within the conduit.

Twisting the hot conductors would help?
 

Julius Right

Senior Member
Occupation
Electrical Engineer Power Station Physical Design Retired
According to
http://www.ecmag.com/section/systems/steel-conduit-holds-steady
?Georgia Institute of Technology focused a three-year study on reducing the effect of EMF on electrical and electronic equipment. Research was sponsored by the Steel Tube Institute (STI) of North America, which is an advocacy group made up of steel conduit manufacturers. The study concluded that steel is the most effective shield for 60 Hz EMF, reducing these fields by as much as 95 percent. Aluminum conduit reduces such fields by about 5 percent, while nonmetallic materials are equivalent to conductors installed in free air.?
See also:
http://steeltubeinstitute.org/steel-conduit/wp-content/uploads/sites/4/2014/09/431GEMIStudy.pdf
 
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