6' fixture whips FMC

Status
Not open for further replies.

MasterTheNEC

CEO and President of Electrical Code Academy, Inc.
Location
McKinney, Texas
Occupation
CEO
As iwire stated, the reduction in conductor size is for the 6' lengths but we make them in all types of lengths (full sized conductors as branch circuit) but call them "Wiring Assemblies -QQYZ" and use standard Type MC Cable and have them in 6', 10', 12' 15' and so on.
 

kwired

Electron manager
Location
NE Nebraska
2011 NEC 410.117 (C) limits tap conductors to 6ft for luminaires.

Sorry but I see some inconsistencies here(not from you but from the NEC) That section is for recessed/flush luminaires - so no problem with the typical use of a "whip" for a typical "troffer". However it appears to limit the length of conductor to 6 feet, so in order to have that long of conductor one would need to have a shorter length of flexible conduit so there is sufficient conductor length to work with at each end.

I also believe the six foot length has a little more to do with the support requirements in 348.30(A) and six foot allowance in exception 3. I first thought maybe the six foot of conductor length in 410.117(C) wasn't intended to apply to a typical "troffer" but rather other recessed luminaires that need some separation for temperature reasons between lamp housing and the junction box - like you usually see on typical "can lights", but then when reading exception 3 to 348.30(A) it does mention 410.117(C), which leaves me wondering about the inconsistency between whether or not we can have six feet of conductor or six feet of flex - can't have both without having too short of conductor to work with.


Outside that situation take a look at some possible tap conductor lengths for "fixture wire" in 240.5(B)(2):

Fixture wire shall be permitted to be tapped to the branch-circuit conductor of a branch circuit in accordance with the following:
20-ampere circuits ? 18 AWG, up to 15 m (50 ft) of run length
20-ampere circuits ? 16 AWG, up to 30 m (100 ft) of run length
20-ampere circuits ? 14 AWG and larger
30-ampere circuits ? 14 AWG and larger
40-ampere circuits ? 12 AWG and larger
50-ampere circuits ? 12 AWG and larger
 

iwire

Moderator
Staff member
Location
Massachusetts
Sorry but I see some inconsistencies here(not from you but from the NEC) That section is for recessed/flush luminaires - so no problem with the typical use of a "whip" for a typical "troffer".

A troffer is a recessed/flush mounted fixture in my opinion.
 

kwired

Electron manager
Location
NE Nebraska
A troffer is a recessed/flush mounted fixture in my opinion.
Correct, the problem is you can't have both six feet of tap conductor and six feet of raceway to put it in and still have enough free conductor at the ends. If we are to have a minimum of 6 inches of free conductor at each end then the raceway would have to be a maximum of 5 feet long or not contain "tap conductors"

However I also believe most of the pre-made "whips" are a listed assembly and the listing maybe gets you around this problem.
 

MasterTheNEC

CEO and President of Electrical Code Academy, Inc.
Location
McKinney, Texas
Occupation
CEO
Correct, the problem is you can't have both six feet of tap conductor and six feet of raceway to put it in and still have enough free conductor at the ends. If we are to have a minimum of 6 inches of free conductor at each end then the raceway would have to be a maximum of 5 feet long or not contain "tap conductors"

However I also believe most of the pre-made "whips" are a listed assembly and the listing maybe gets you around this problem.
My opinion is it says "AC or MC Cable".as that is what we use for our whips..that would be the entire assembly so having the cable 6' with additional 6" of conductors at each end would still be a 6' cable.
 

iwire

Moderator
Staff member
Location
Massachusetts
My opinion is it says "AC or MC Cable".as that is what we use for our whips..that would be the entire assembly so having the cable 6' with additional 6" of conductors at each end would still be a 6' cable.

It seems like a stretch to say that.

I think kwired is technically correct even though I would never expect an inspector to enforce it that way.

Or are you suggesting that if I was to use MC cable for a feeder tap of say a switchgear bus that any length I have stripped and is inside the enclosure does not count towards the length of the tap conductors?
 

kwired

Electron manager
Location
NE Nebraska
It seems like a stretch to say that.

I think kwired is technically correct even though I would never expect an inspector to enforce it that way.

Or are you suggesting that if I was to use MC cable for a feeder tap of say a switchgear bus that any length I have stripped and is inside the enclosure does not count towards the length of the tap conductors?
Agreed, tap rules apply to conductor length, nothing mentions raceway or cable sheath length, one could make a tap in a wireway, then pass the conductor through a raceway then into the enclosure containing the overcurrent device, but you only get so much allowed conductor length and do not start over just because it has a change of routing method.
 

MasterTheNEC

CEO and President of Electrical Code Academy, Inc.
Location
McKinney, Texas
Occupation
CEO
It seems like a stretch to say that.

I think kwired is technically correct even though I would never expect an inspector to enforce it that way.

Or are you suggesting that if I was to use MC cable for a feeder tap of say a switchgear bus that any length I have stripped and is inside the enclosure does not count towards the length of the tap conductors?
My reference is to the what is considered 6' in terms of the cable itself as it pertains to the length of whips. When the conductors are the issue (as in your example) then that is what is counted....when dealing with for example supporting requirement as in 6' of unsupported cable from the last point of support to a luminaire for example...the 6' is the cable.

However, as I did not appear to read the statement correct.....in regards to the tap rules the conductor length is king...thats why in the case of THIS tap allowance I would full size them (with our Type MC of course) and negate the tap issue and run full sizes.:slaphead:
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Most fixture whips are made with 3/8" FMC which has a maximum length of 6'. {348.20(A)}
 

MasterTheNEC

CEO and President of Electrical Code Academy, Inc.
Location
McKinney, Texas
Occupation
CEO
Most fixture whips are made with 3/8" FMC which has a maximum length of 6'. {348.20(A)}
lol..the whip or the conductors in the whip....:angel:

Keep in mind that "whips" can also be wire assemblies (QQYZ) that are comprised of product like Type MC that is already produced and permitted under Art. 330 as you know. We produce "whips" but none are FMC so not sure I would say most....but many indeed.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
lol..the whip or the conductors in the whip....:angel:

Keep in mind that "whips" can also be wire assemblies (QQYZ) that are comprised of product like Type MC that is already produced and permitted under Art. 330 as you know. We produce "whips" but none are FMC so not sure I would say most....but many indeed.


The OP asked specifically about FMC so the section that I mentioned 348.20(A) would apply. That section limits the length of the 3/8" FMC to 6'.
 

al borlan

Member
Location
Newport, Mi.
Tap conductors

Tap conductors

thanks iwire,:thumbsup: I totally glossed over the TAP CONDUCTOR wording. You cleared it up with the branch circuit post.
I need a vacation.:p
 
Status
Not open for further replies.
Top