Bundling?

[Marc M]

Hate to beat a dead horse, just wanted to get an opinion on the NM entering the panelboard.

[Rick Cantrell]

Hate to beat a dead horse, just wanted to get an opinion on the NM entering the panelboard.

Are the wires bundled? Maybe, maybe not, but likely so

Did the electrician derate, do the calculation, and consider the derated value when they were installed? Who knows

[Jim Port]

Is the nipple or conduit 24" or less? Like Rick said, there is no way to answer based on that pic.

[Ted Menelly]

Hate to beat a dead horse, just wanted to get an opinion on the NM entering the panelboard.


From what I a looking at as far as the location of that box I would and can only say that it appears that it has to be a minimum of 2 feet to where those wires go inside thru a conduit.

[Robert Meier]

Like others have stated the question is unanswerable given the information and that particular photo.

[H.G. Watson, Sr.]

The raceway might have been overfilled/overstuffed - beyond the permitted percentage of the cross sectional area, but cannot be confirmed from the photo.

[Marc M]

I get it...

[Gunnar Alquist]

Marc,

If that is a conduit, then as has been said, who knows. If that is a strain relief clamp, then I believe it to be improper. If I remember correctly, strain relief clamps are good for two flat (2-wire with ground) cables or one round (3-wire with ground) cable.

[Jerry Peck]

That is so wrong in so many ways ...

[Marc M]

That is so wrong in so many ways ...

You have my attention...please go on..

[Robert Meier]

You have my attention...please go on..

Can you provide more details and/or photo's to further explain what we're looking at?

[Marc M]

Id love to but that's all there is. New house, new panel. I'm guessing the installer probably used the conduit to help with routing the conductors into the panel.
I honestly cant see conduit running from the panel to the house. I'm sure the conductors are run in a drywalled chase, out of conduit.

[Jerry Peck]

You have my attention...please go on..


Are the wires bundled? Maybe, maybe not, but likely so ...


The raceway might have been overfilled/overstuffed - beyond the permitted percentage of the cross sectional area, ...


If that is a strain relief clamp, then I believe it to be improper. If I remember correctly, strain relief clamps are good for two flat (2-wire with ground) cables or one round (3-wire with ground) cable.

The above are all applicable from what appears to be shown in that photo:
- If that is conduit, and if that is over 24" long which is likely is, then lack of maintaining spacing would apply. I'm going to guess that there are *at least* 10 NM cables in there, which means *at least* 20 current carrying conductors, so derating would be by a hefty amount.
- Let's take the worst case first: That those conductor run up into an attic of a one story house:
- - Let's presume the attic only gets to 123-131 degrees during the hottest time of the year - that is a derating factor of 0.76 for ambient for NM-B, or 30 amp derating capacity for #12 AWG NM-B x 0.76 = 22.8 amps derated for ambient x 0.50 for 10-20 conductors = 11.4 amps derated = not even suitable for a 15 amp breaker. And that is for *only* up to 20 conductors and I am estimating *at least* 20 conductors.
- Let's take a less sever case second: That the conductors run up into a floor space in a two story house:
- Let's presume that conduit is in the exterior wall with no insulation around it (that is a reasonable presumption because of the conduits size), and let's presume that the ambient temperature never gets over 87-95 degrees during the hottest time of the year - that is a derating factor of 0.96 for that NM-B, the derating would be 30 amps x 0.96 = 28.8 amps x the 0.50 for 10-20 conductors (which is best case as I am thinking more than 20) - 14.4 amps = STILL not suitable for a 15 amp breaker.
- Let's go next-to-best case now:
- - no derating for ambient at all, just for the number of conductors: 30 amps x 0.50 = 15 amps = just barely suitable for a 15 amp breaker, but still not suitable for the expected 20 amp breaker for the #12 AWG.
- Let's go to the best case now:
- - Let's presume that is not a conduit, just a large NM cable clamp and no derating for ambient = no problem for ampacity, but there is that problem with all those NM cables not being properly secured to the enclosure.

[Erik Pendleton]

The above are all applicable from what appears to be shown in that photo:
- If that is conduit, and if that is over 24" long which is likely is, then lack of maintaining spacing would apply. I'm going to guess that there are *at least* 10 NM cables in there, which means *at least* 20 current carrying conductors, so derating would be by a hefty amount.
- Let's take the worst case first: That those conductor run up into an attic of a one story house:
- - Let's presume the attic only gets to 123-131 degrees during the hottest time of the year - that is a derating factor of 0.76 for ambient for NM-B, or 30 amp derating capacity for #12 AWG NM-B x 0.76 = 22.8 amps derated for ambient x 0.50 for 10-20 conductors = 11.4 amps derated = not even suitable for a 15 amp breaker. And that is for *only* up to 20 conductors and I am estimating *at least* 20 conductors.

Why would the 2 derates be cumulative? I understand derating wire in the attic, and derating wire that is bundled, but if they are not bundled in the attic, what sense is there in applying both derates for the whole wire? I seems to me you you derate the wire for bundling, and derate the wire for the attic temp, and take the lower of the 2, not combine them?

Just asking for a source that indicates derating factors for different areas are cumulative across areas. Seems counter intuitive.

[Roland Miller]

Why would the 2 derates be cumulative? I understand derating wire in the attic, and derating wire that is bundled, but if they are not bundled in the attic, what sense is there in applying both derates for the whole wire? I seems to me you you derate the wire for bundling, and derate the wire for the attic temp, and take the lower of the 2, not combine them?

Just asking for a source that indicates derating factors for different areas are cumulative across areas. Seems counter intuitive.


If the conductors are both bundled and run through a high ambient temperature, the NEC requires both adjustments be made for those conductors affected. If part of the conductors only are bundled or are only ran through a higher temperature, only that single adjustment needs to be made. Both conditions add heat to the conductor as does the current flow. Since we are protecting the insulation (which is temperature rated and the weak link, usually) all adjustments need to be applied that the conductor is exposed to. There is not one specific statement that states this and that is one reason why the NEC is NOT a training manual..The other things to consider are the temperature limitations of the terminations, splices, raceway, etc..