Panels / wires - what's acceptable in my case?

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  #1  
Old 04-15-06, 11:51 AM
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Panels / wires - what's acceptable in my case?

Could I feed a 200A sub panel (with 60A main breaker for now) using 2/0 Cu THHN in 2 PVC conduit from my 100A service panel (both in the basement 10' apart)? In the future, when the service is upgraded to 200A (and the third meter), this 200A sub panel will serve as a main panel for the mother-in-law duplex (apt3) and for the detached garage with its own 100A? sub panel.

I also want to know whether it is acceptable to feed a 125A sub panel in apt3 using four #1 THHN Cu conductors in a 1.5 sch40 PVC conduit from my 200A (sub) panel in the basement (35 run).

Here is what I have now: Service comes into the basement of the 2 Fam. house (MA) via 1 1/4"-1 1/2" conduit (3 conductors - can't read the labeling; 2/0 AL?), splits into two meters (300 VAC, 100A, Palmer AA switch) and then to the two identical load centers (Siemens G2020MB1100) for apt1 and apt2. Each load center is protected with the main double 60A breaker.

Any comments are greatly appreciated. Load demand for apt3 is unlikely to exceed 125A - there is NG in the apartment.
 
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Old 04-15-06, 12:14 PM
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You can certainly feed 2/0 with a 60 amp breaker, but it's rated for 195 amps, so you could not feed it with a 200 Amp breaker later.

If the panels are only 10' apart I would use EMT, the PVC route is kinda cheezy.

#1 is good for the 35' run but again, I'd pass on the PVC.
 
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Old 04-15-06, 12:34 PM
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Cheetah_Boxes, thanks for the prompt reply. Should I be using 3/0 Cu to be able to use 200A breaker? 2" EMT in the basement for 10' run will be no problem. As for the 35' run, I am using PVC conduit due it's flexibility. 1.5 PVC is already purchased but not installed. I can easily replace it with the EMT if there are resons other than it being "cheezy" ;-) If I choose to replace, should I go with the 2" instead of 1.5"?
 
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Old 04-15-06, 01:01 PM
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Originally Posted by Cheetah_Boxes
You can certainly feed 2/0 with a 60 amp breaker
You would need other clips because surely 2/0 won't fit in a 60A breaker.

> but it's rated for 195 amps,
200A feeder.

> so you could not feed it with a 200 Amp breaker later.
Why not?
 
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Old 04-15-06, 01:11 PM
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Originally Posted by handyal
1.5 PVC is already purchased but not installed.
You can put five #1 THHN in 1.5" Sch40 or EMT.

> If I choose to replace, should I go with the 2" instead of 1.5"?
Why? Might you want to pull larger conductors someday?
 
  #6  
Old 04-15-06, 01:35 PM
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Originally Posted by bolide
You can put five #1 THHN in 1.5" Sch40 or EMT.

> If I choose to replace, should I go with the 2" instead of 1.5"?
Why? Might you want to pull larger conductors someday?
bolide, thanks for weighing in :-)

Are you saying "You can put five #1 THHN in 1.5" Sch40 or EMT" to stress that the 1.5" is an adequate conduit size for #1 Cu, or that I do need the fifth conductor? What would that be?

I've considered a possibility of pulling the 200A rated conductors (2/0 Cu or 3/0 Cu), but didn't see the real need (considering that the main panel is 200A). It is unlikely that I'll be pulling conductors larger than #1 (125A).
 
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Old 04-15-06, 02:06 PM
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Bolide's responses remind me that I'd better read the code more closely.
 
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Old 04-15-06, 02:21 PM
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Originally Posted by handyal
to stress that the 1.5" is an adequate conduit size for #1 Cu
Correct.

> I've considered a possibility of pulling the 200A rated conductors (2/0 Cu or 3/0 Cu),

> It is unlikely that I'll be pulling conductors larger than #1 (125A).
If you may use the feeder table, #2 is 125A.
 
  #9  
Old 04-15-06, 02:35 PM
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Originally Posted by bolide
If you may use the feeder table, #2 is 125A.
If I will run into problems locating / purchasing #1 annealed Cu, I will consider #2. Also, given the contentious nature of the feeder table (among others) interpretation by AHJ, I'd probably better off on the "over-kill" side (#1), no?
 
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Old 04-15-06, 04:00 PM
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> If I run into problems locating / purchasing #1 annealed Cu

I've never had a problem getting it in black. Getting it in white and red insulation can be a problem sometimes (usually though, for a piece a lot longer than 35').

> given the contentious nature of the feeder table (among others) interpretation by AHJ,
> I'd probably better off on the "over-kill" side (#1), no?
The first question is whether you believe #2 is safe.
If you are okay with it, then just ask your AHJ before you buy #2. Many have no problem with using the table.

Even without the feeder table, I think that #2 pretty much qualifies for a 125A breaker by the rule of round up to the next stardard breaker size. So I don't see it as a problem.

The same goes for rounding 195 up to 200A.
 
  #11  
Old 04-15-06, 08:25 PM
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Originally Posted by bolide
> If I run into problems locating / purchasing #1 annealed Cu

I've never had a problem getting it in black. Getting it in white and red insulation can be a problem sometimes (usually though, for a piece a lot longer than 35').

> given the contentious nature of the feeder table (among others) interpretation by AHJ,
> I'd probably better off on the "over-kill" side (#1), no?
The first question is whether you believe #2 is safe.
If you are okay with it, then just ask your AHJ before you buy #2. Many have no problem with using the table.

Even without the feeder table, I think that #2 pretty much qualifies for a 125A breaker by the rule of round up to the next stardard breaker size. So I don't see it as a problem.

The same goes for rounding 195 up to 200A.

Bolide, Thank you! I have read many of your posts and found them enlightening, uplifting, and encouraging. Your friendly attitude and tolerance of benign ignorance (of people like myself) is even more impressive than your knowledge of Electricity. Take care,

al
 
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