"Example" of a Code-compliant circuit

[pattbaa]

I am baffled by the meaning and intent of Art 240.5 ---- Fixture Wires, (B), (2)Fixture Wire which reads------------

""Fixture wire shall be permitted to be tapped to the B-C (conductors as follows)"

"(2) 20 amp (B-C)----- #16 ( fixture wire)--- up to 100 ft. of run-lenth"

A description of an "example" installation that complies with the Art. may clarify the intent of the Art for me. Also ,a responce to these relevant questions----

#16 TFFN fixture wire is permitted to be tapped/connected to B-C conductors protected by a 20 amp breaker, and the fixture wire is permitted to be extended 100 ft. from the point of connection. T or F ?

The permissible load on the #16 fixture wire is a single luminaire only. ( not stated but implied?) T or F ?

The #16 fixture wires must be enclosed in an approved Wiring Method ( not stated but implied?) T or F ?

 

[jwelectric]

Re: "Example" of a Code-compliant circuit

Would it need to comply with 240.21 (C)
(4) Taps Over 7.5 m (25 ft) Long. Where the feeder is in a high bay manufacturing building over 11 m (35 ft) high at walls and the installation complies with all the following conditions:
(1) Conditions of maintenance and supervision ensure that only qualified persons service the systems.
(2) The tap conductors are not over 7.5 m (25 ft) long horizontally and not over 30 m (100 ft) total length.
(3) The ampacity of the tap conductors is not less than one-third the rating of the overcurrent device protecting the feeder conductors.
(4) The tap conductors terminate at a single circuit breaker or a single set of fuses that limit the load to the ampacity of the tap conductors. This single overcurrent device shall be permitted to supply any number of additional overcurrent devices on its load side.
(5) The tap conductors are protected from physical damage by being enclosed in an approved raceway or by other approved means.
(6) The tap conductors are continuous from end-to-end and contain no splices.
(7) The tap conductors are sized 6 AWG copper or 4 AWG aluminum or larger.
(8) The tap conductors do not penetrate walls, floors, or ceilings.
(9) The tap is made no less than 9 m (30 ft) from the floor.

 

[infinity]

Re: "Example" of a Code-compliant circuit

Wires run through say a row of fixtures are not required to be sized according to the branch circuit OCPD. They could be fixture wires. So a 50' row of fixtures wired end to end could have a #12 feed and continue through the fixtures with a smaller fixture wire say #16 or a conductor sized according to 240.5. The connected load on the fixture wires can't exceed the values in table 402.5.

[ August 02, 2005, 03:20 PM: Message edited by: infinity ]

 

[pattbaa]

Re: "Example" of a Code-compliant circuit

Would it be Code-compliant to tap 16 TFFN wire off a 20 amp B-C and extend the #16 tap conductors 50 ft in FMC routed above a suspended ceiling to a single fixture?

 

[iwire]

Re: "Example" of a Code-compliant circuit

Looks like it.

 

[kiloamp7]

Re: "Example" of a Code-compliant circuit

I have always advocated the use of the branch circuit tap rules for known loads such as lighting fixtures.

A common scenario may have 20A BC OCP & #12 wire, with #14 or #16 taps for a short distance down through the "fixture stem" to each fixture.

Only thing that bothers me is NEC term fixture wire that is used in Art. 240 & 402.

Reason is because the tap wires I use may not necessarily be type TFFN or one of those listed in Art. 402. Usually I use good ole THHN/THWN.

Anyone see problems with this?
I am aware of some fixtures requiring a certain temperature rating for the wires connecting to the fixture.

[ August 02, 2005, 11:29 PM: Message edited by: kiloamp7 ]

 

[fc]

Re: "Example" of a Code-compliant circuit

Originally posted by pattbaa:
Would it be Code-compliant to tap 16 TFFN wire off a 20 amp B-C and extend the #16 tap conductors 50 ft in FMC routed above a suspended ceiling to a single fixture?

You need to look at 410.67 (C) The tap max would be 6ft. You would have to install an outlet box. That's the way I read it.

 

[iwire]

Re: "Example" of a Code-compliant circuit

Originally posted by fc:
You need to look at 410.67 (C) The tap max would be 6ft. You would have to install an outlet box. That's the way I read it.

410.67(C) is about the whip between the lamp socket and the fixtures junction box, like you would see on a high hat.

 

[fc]

Re: "Example" of a Code-compliant circuit

I think you would install a outlet box for the light that the fixture hangs from. If you run 50' of FMC to a branch circuit outlet box then I would think you would be using it for a branch circuit wiring and I don't think you can use fixture wire for that. The fixture wire is for tap conductors and I still think 410.67 (C) comes into play because you taped the branch circuit box.

 

[fc]

Re: "Example" of a Code-compliant circuit

Originally posted by iwire:

Originally posted by fc:
You need to look at 410.67 (C) The tap max would be 6ft. You would have to install an outlet box. That's the way I read it.

410.67(C) is about the whip between the lamp socket and the fixtures junction box, like you would see on a high hat.

410.67 (C) is for tap conductors

 

[iwire]

Re: "Example" of a Code-compliant circuit

Originally posted by fc:
410.67 (C) is for tap conductors

Yes, in section of 410 called part XI. Special Provisions for Flush and Recessed Luminaires (Fixtures)

The tap conductors that section is talking about are the high temperature conductors typically factory installed between the socket and the junction box mounted on the fixture.

 

[fc]

Re: "Example" of a Code-compliant circuit

Originally posted by iwire:

Originally posted by fc:
410.67 (C) is for tap conductors

Yes, in section of 410 called part XI. Special Provisions for Flush and Recessed Luminaires (Fixtures)

The tap conductors that section is talking about are the high temperature conductors typically factory installed between the socket and the junction box mounted on the fixture.

410.67 (c) Tap conductors of a type suitable for temperature encountered ---- I don't see high temperature. So what your saying is that if my fixture has # 16 temerature wire I can run it 100' ? I am sorry but I don't read it that way. I think you would have to install a outlet box not more than 6' and that's where I would make the tap.Or at the outlet box that the fixture hangs from or at the fixture itself.

[ August 11, 2005, 05:23 PM: Message edited by: fc ]

 

[pattbaa]

Re: "Example" of a Code-compliant circuit

It it permissible to connect #16 TFFN fixture-wire to Branch-Circuit conductors protected by a 20 amp C-B and then route the #16 FW's directly thru four channel-type flourescent fixtures, each 8 ft. in lenth, and then terminate the FW's on ballast-connections that limit the FW current to 8 amps?

The last connection-point for FW's is 48 ft from the tap-connection point.