Strapping NM Cable

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RCRosson

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Thousand Oaks, CA
While the NEC states that NM be strapped every 4' across "open" areas (the same as flex) I read a statement from the California Building Code, under sub heading of earthquake, that due to shearing effects of buildings moving in opposite directions, NM cable should NOT be strapped across open areas (namely over the top of ceiling joists) EXCEPT within 12" of a junction or device, or to protect the Cable from damage. Could someone please help me confirm or deny this. I know I read the code revision but I am having trouble finding the actual code that I read. Thank you.
 
Well they gave you an exemption "for protecting the cable from damage" so all you have to do is say you are protecting it from damage.
Perhaps you should look at the behavior of building during an earthquake. Generally, each building will sway by itself but will behave intactly. Now if you had a two part building, the two halves could have a different frequency so you should leave, say, 4" of slack between the sections.
~Peter
 
peter said:
Well they gave you an exemption "for protecting the cable from damage" so all you have to do is say you are protecting it from damage.
Perhaps you should look at the behavior of building during an earthquake. Generally, each building will sway by itself but will behave intactly. Now if you had a two part building, the two halves could have a different frequency so you should leave, say, 4" of slack between the sections.
~Peter
Click to expand...

Peter,
Perhaps the OP could use DataComm "J" hooks ?
Perhaps the OP could form several loops to make the "slack"?
:)
 
Earthquakes and NM (romex)

Earthquakes and NM (romex)

This code "update" was regional to Los Angeles or California. The reason for the action was that during the Northridge, CA quake in the 90's, numerous homes suffered severe electrical damage because of the romex being nailed tight across the top of truss joists. The swaying action literally sheared the wires by the truss's pulling in opposite directions. This is for horizontal installs, across the top of joists or in soffit's. As I said, this came up in an update to either California or Los Angeles Building Code; not the NEC.
 
RCRosson said:
I read a statement from the California Building Code, under sub heading of earthquake, that due to shearing effects of buildings moving in opposite directions, NM cable should NOT be strapped across open areas (namely over the top of ceiling joists) EXCEPT within 12" of a junction or device, or to protect the Cable from damage. Could someone please help me confirm or deny this.
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Got a link to this? Where are you reading this? LA building code?

I see nothing in 334 of the CEC for this....
 
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RCRosson said:
Hey E.H.

Thats the problem....I know that it was either LA or California Building code under Earthquake; vs. CEC or NEC.

I know I read it, but feel like I'm spinning my wheels trying to find it.

Thanks
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You might be???? Might not? I was taking a look at the LA codes which are fascinating... And the specific codes don't seem to modify the CEC????

Anyway - in the past I have too seen some interesting 'suggestions' on seismic literature - maybe you saw it in one of those??? But IMO if building movement is going to be an issue for any electrical circuits - then the building has BIGGER PROBLEMS...... ;)
 
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