mc suport in suspended celings feeding luminaires

jkrauss

Member
art 330.30(D)(2)[nec '08] states if the cable feeding a luminaries is not over 6 feet it does not have to be supported. My question is if the same cable is terminated in a jbox in the accessible celling will it have to be supported with in 12 inches of the jbox 330.30 b .
 

jimdavis

Senior Member
I disagree. According to 330.30(D) the mc connector itself qualifies as a means of support in this application. Therefore a 6' length of mc cable running between a junction box and a luminaire would require no additional support.
 

kwired

Electron manager
Location
NE Nebraska
art 330.30(D)(2)[nec '08] states if the cable feeding a luminaries is not over 6 feet it does not have to be supported. My question is if the same cable is terminated in a jbox in the accessible celling will it have to be supported with in 12 inches of the jbox 330.30 b .
Not sure but guessing this is the same in 2014, here is what is in the 2014:

"Is not more than 1.8 m (6 ft) in length from the last point of cable support to the point of connection to luminaires or other electrical equipment and the cable and point of connection are within an accessible ceiling. For the purpose of this section, Type MC cable fittings shall be permitted as a means of cable support."

Last point of cable support would have to be the connector on the last junction box or last luminaire if daisy chained. If the length is 6 feet or less it is saying no additional support is needed but it must also be within an accessible ceiling. There is similar rules for flexible conduits and for other cable types as well.

No strap. But if you daisy chain then it becomes a raceway and needs a strap
How does it become a raceway? It is still a cable wiring method regardless or length or installation methods.
 

kwired

Electron manager
Location
NE Nebraska
If you go fixture to fixture and length is less then 6 feet no additional strapping should be necessary, but wouldn't be prohibited either.

Biggest thing that often discourages the fixture to fixture method is use of FMC as the EGC is not allowed over six feet of total EGC path, and then people kind of get it in their head that fixture to fixture just isn't allowed an forget exactly why the generally don't do it, plus the support rules sneak in there as well.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Although the illustration below is for article 320 it is the same for article 330



Roger
 

electricalist

Senior Member
Location
dallas tx
I thought if it were from a j box and flexed down to the light and under 6' no strap was needed and mc / aluminum had to be strapped 12" from termination. Nothing can be laying on grid as means of support there for independant ceiling wires must be used connected at both ends not because its an electrical code but a bldg code. Ceiling grid manufacturer would have to sing off saying the grid is rated to hold the mc
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
I thought if it were from a j box and flexed down to the light and under 6' no strap was needed and mc / aluminum had to be strapped 12" from termination. Nothing can be laying on grid as means of support there for independant ceiling wires must be used connected at both ends not because its an electrical code but a bldg code. Ceiling grid manufacturer would have to sing off saying the grid is rated to hold the mc
Not per the NEC. Read all the 3XX.30 sections.

With that being said, local building codes may be another story and 410.36 may be of some interest too.

Roger
 

arcsnsparks98

Senior Member
Location
Jackson, TN USA
Caddy makes these awesome little clips just for securing mc to the grid. They hold it in place quite nicely and, when installed properly, do not interfere with removing the tile.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Not per the NEC. Read all the 3XX.30 sections.

With that being said, local building codes may be another story and 410.36 may be of some interest too.

Roger
I should have included 300.11 as well

Roger
 

kwired

Electron manager
Location
NE Nebraska

I must have missed something. I didnt know a connector could be used as a means of support. But I thought what I said was the same as 300.11
I don't see what 300.11 has to do with a connector being used as a means of support. I will say in a situation where no other support means is necessary that kind of leaves the connector tasked with providing support to at least some extent.
 

electricalist

Senior Member
Location
dallas tx
I don't see what 300.11 has to do with a connector being used as a means of support. I will say in a situation where no other support means is necessary that kind of leaves the connector tasked with providing support to at least some extent.
Someone said my statement was not true by nec code and that 300.11 would help. Sorry if I misunderstood
 

kwired

Electron manager
Location
NE Nebraska
Someone said my statement was not true by nec code and that 300.11 would help. Sorry if I misunderstood
300.11 does address supporting of wiring methods, but doesn't address connectors being allowed as the support method, yea or nay, and doesn't cover the six feet of unsupported methods allowed in specific instances. You have to read other sections to answer some of those questions.
 
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