- Location
- Illinois
- Occupation
- retired electrician
I don't think you have any choice.
Wire Derate in Panduit
- Thread starter dasarmin
- Start date
- Status
I don't think you have any choice.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I agree, but with the proviso that if it is not clear that the panel builder intended for field wiring to be added to the Panduit, I would not feel safe in ignoring any possible derating of the original wiring.
Aleman
Senior Member
- Location
- Southern Ca, USA
But the NEC doesn't specify fills for panduit and other wireways commonly used in control panels.
For me, I just make sure my wires/cables are sized right per NEC and run it into the panel. The NEC rules don't exist
for the raceway fills in the box, so how can they apply to anything other than wire sizing in this case?
Aleman
Senior Member
- Location
- Southern Ca, USA
It will be clear if the builder intended wiring to be added to the panduit. Usually panels have to hook up to the stuff they
are running, and in a panel that means the panduit or whatever they used. Now...after a year or so lot's of these wires will
no longer be in the panduit but hanging all over the place from people screwing with things. Think of the panel like a big
gutter.
- Location
- Illinois
- Occupation
- retired electrician
Just because there is no fill requirement does not mean that the current carrying conductors do not produce heat. It is my opinion, that the derating rules apply to the field installed conductors in the panel any time that the conductors are installed without maintaining spacing between the conductors. Also the derating rules are really wire sizing rules.
Note, that per the panel comment on my proposal, CMP6 does not agree with me.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Because the wording in 310.15(B)(3)(a) is explicit even if the CMP can't read. That would apply anywhere the conductors were installed without spacing for more than 24".
- Location
- Massachusetts
The rules for derating apply to conductors that are run together without spacing. It is irrelevant what is holding them in a group, it could be tie wraps, it could be a raceway or it could be panduit. In any case they will run warmer and must be derated.
Aleman
Senior Member
- Location
- Southern Ca, USA
All good points that I haven't put a lot of thought into before.
Having worked with machinery and controls most of my adult life...my observation is that most people who
build this stuff are just cramming wires into the cable tray whether it be Panduit or etc. Where I work now,
we install AC units on all drive panels and I am generous with wire size. Meaning that if it's close I go up a size.
Haven't thought about it but I guess I tend to derate wire size, mostly because I have seen a lot of burnt up stuff.
Interesting thread.
Having worked with machinery and controls most of my adult life...my observation is that most people who
build this stuff are just cramming wires into the cable tray whether it be Panduit or etc. Where I work now,
we install AC units on all drive panels and I am generous with wire size. Meaning that if it's close I go up a size.
Haven't thought about it but I guess I tend to derate wire size, mostly because I have seen a lot of burnt up stuff.
Interesting thread.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
In many cases the conductors are without spacing for only a few feet so the exception may apply and derating isn't required anyway.
- Status