Hi Don, great to see you made it into the pool !! Have you seen Ralphesq around anywhere ?

Now I've got one for you guys.

Will be running about 150 ft. EMT on outside of building, 3 # 1 AWG + # 6 Ground. Will I have to derate the ampacity since this will at times be in direct sunlight, & So. Calif. definately gets above 86 deg. F at times.
Thanks
Mike B (AKA Byter)

Byter: 06/05/2002

I have not as yet heard anything from RAEsquivel.

Yes I would definitely derate the wires by increasing the AWG No.1 wire(s) to AWG No.1/0 wire(s) size.The grounding wire AWG No. 6 may be OK.

You did not indicate what type of wire you would be using or the Ampere load, however the 2002 NEC Article 310.10, Tables 310.13 & 310.61 cover this application.

If the temperature outside the thinwall is going to reach 86-degrees, then the temperature inside the conduit will probably be higher depending on the ampere load & how long the temperature outside is at 86-degrees.

Please do not post email addresses in open forums. Registered members can view your email address in your profile, if you wish to provide it.

[This message was edited by donaldekliros on 06-05-02 at 03:27 PM.]

[This message was edited by MiranndaGrey on 07-20-02 at 01:37 PM.]

Byter: I now understand (I think) what you are saying. I knew emt, and I'm familiar with wire sizes and even amp ratings for each. I guess I didn't pay attention to the question and terminology. DERATE means to assume you're using a wire of smaller size, correct? As in: My shop is 90 feet from my house, so if I'm going to run a circuit there, to maintain about 15 amps for my tools, I need to run a #10 wire on a 20 amp breaker? I know this is oversimplified, but I think I get it.
12 wire:20amps, 14 wire: 15 amps? etc

Thanks, Don... I didn't realize that ambient temperature affected amp ratings. How does it?

Actually, I know just enough about electrical stuff and wiring to be dangerous, inasmuch as sometimes I think I know more than I do.
Thanks guys.

06/05/2002

DaveMac:

I believe that you have the right concept of derating the wire(s), however what derating in this concept means in regards to temperature is this:

When the wire that is being used has a current running thru it it will raise the temperature of the wire up to whatever that current will take it to.

In addition, then, the ambient temperatutre will also add to the temperature of the wire, so therefore to be sure that you will be safe in operating the device for which the wire was installed you will generally increase the size of the wire to take into effect the temperature of both the wire & the ambient outside temperature when determining the size of the wire used.

Please do not post email addresses in open forums. Registered members can view your email address in your profile, if you wish to provide it.

[This message was edited by MiranndaGrey on 07-20-02 at 01:39 PM.]

Thanks Don.

Thanks Don:
I plan on useing THHN (90 deg C, 194 geg. F). Will be operating one Motor with a Full load Amp. of 62 Amp. on 3 phase & fed from 100 amp breaker.

Do you think I still need to go to 1/0 ?

Byter 06/05/2002

If all that you plan on loading this circuit with is 62-amperes, then I would think that AWG No.1 wire would be sufficient.

AWG No.1 THHN wire with a 90-degree temperature rating is rated for 150-ampere so you will be loading the wire to somewhat less than half its rated load capacity.

Please do not post email addresses in open forums. Registered members can view your email address in your profile, if you wish to provide it.

[This message was edited by MiranndaGrey on 07-20-02 at 01:39 PM.]

tried to rate you don but said something about feedback val. i haven't figured that out yet. time to go back to home but you get 4 stars from me anyway