Sub panel wire sizing.

[6togo]

Probably 2 dozen rec. a dozen led panels, outside wall lighting, Mini split system 240v, air comp 240v, lift 240v, tire machine 120v, tire balancer120v, welding outlet 240v, and second stacker lift 240v down the road. This is the bulk of it give or take some additional lighting in the attic. It's just me in there so like it's been said I can't run it all at the same time.

 

[mike93lx]

Probably 2 dozen rec. a dozen led panels, outside wall lighting, Mini split system 240v, air comp 240v, lift 240v, tire machine 120v, tire balancer120v, welding outlet 240v, and second stacker lift 240v down the road. This is the bulk of it give or take some additional lighting in the attic. It's just me in there so like it's been said I can't run it all at the same time.

Single person is the key. About max would be hvac, lighting a compressor and a plasma cutter.

Barring an EV charger, not many single person shops could hit 90a draws

 

[6togo]

What's the max wire size that will fit in a 90a breaker?

 

[mike93lx]

What's the max wire size that will fit in a 90a breaker?

Depends on the brand

 

[pattenp]

What's the max wire size that will fit in a 90a breaker?

2/0 is fairly common to fit in 90A breaker. I know that's what it is for Square D.

 

[wyliesdiesels]

180' is pushing it a little with #2 al

 

[jeepxj]

What's the max wire size that will fit in a 90a breaker?

pins can make it 500kcmil no problem

 

[6togo]

Probably going to step up to 2/0 for the run think it's better off. Will 2/0-2/0-1-4 MHF work it's a few hundred cheaper than 2/0-2/0-2/0-1?

 

[6togo]

So I think I have a game plan I'm going to run 2/0-2/0-2/0-#1 SER though the old garage roughly 40' to a junction box then run the same wire size in XHHW-2 the other 140' in conduit right into the new panel. This saves me having to conduit the old garage and having any problems pulling wire though the extra bends. So can I get away with 1 1/2" pic conduit or do I need 2"?

​

 

[mike93lx]

2". That is a 41% fill on 1.5, so over limit. I think you can downsize the EGC, but even so, you'd be right at 40%.

 

[6togo]

I keep getting different results on the cable fill one is just over 40% at 40.78 and another is around 38%. Can you be at the 40% limit?

 

[jeepxj]

I dont think anyone who has pulled wire thru conduit has ever said: sure am glad we didn't upside that since it was so close to fill%. that savings was worth it.

 

[6togo]

Well I know too big is not always good either.

 

[jeepxj]

Well I know too big is not always good either.

one size up.

we're not saying put in a tunnel

 

[6togo]

Understand just trying not to waste money if I don’t need too.

 

[mike93lx]

Understand just trying not to waste money if I don’t need too.

It isn't a waste. Do the 2". Heck 2.5" wouldn't be a waste. That is what I would call one size up. 2 is the right size

If you run the 1.5" you'll be swearing about not spending the few extra bucks on 2"

 

[jeepxj]

Understand just trying not to waste money if I don’t need too.

you will thank yourself for doing 2".

1.5" if you want to suffer.

 

[sparky 1971]

Use 2". There has only been one time in my life I used 1-1/2 and that's because I had to go between a ceiling and some duct work and 2" wouldn't fit. Every single time before and since, whether I was working for a contractor or myself, if was too big for 1-1/4, I'm using 2".

 

[6togo]

Looks like 2” it will be don’t need any added headaches!

 

[mike93lx]

one size up.

we're not saying put in a tunnel

You aren't saying to put in a tunnel...

 

[wyliesdiesels]

another vote for 2"... youll thank us later..

 

[6togo]

Next question can I drop a 12 or 14 wire in the 2" conduit with the 2/0 lines or should I run a separate 3/4" conduit for the small wires? I have lights I need on a 3 way for the front of the garage.

 

[jeepxj]

Next question can I drop a 12 or 14 wire in the 2" conduit with the 2/0 lines or should I run a separate 3/4" conduit for the small wires? I have lights I need on a 3 way for the front of the garage.

can you do that with a single feeder to out building rule?

maybe on a lamp post by the door?

 

[wyliesdiesels]

can you do that with a single feeder to out building rule?

maybe on a lamp post by the door?

yes code allows this for controlling lights

the power source for the garage light however needs to come form the garage subpanel

 

[mike93lx]

can you do that with a single feeder to out building rule?

maybe on a lamp post by the door?

The power has to be sourced at the outbuilding and the wiring coming back is just a switch loop, AFAIK

 

[jeepxj]

ahhh interesting. thanks

 

[6togo]

So what I have is when leaving my mud room there is a 3 way switch for the outside wall lights on the 1st garage and inside the 1st garage is a 3 way switch for those as well. So considering I will be in the panel next to the switch I was hoping to run a 3 wire down to the new garage so I could turn on this wall lights at the same time.

 

[6togo]

So I came across someone local that has a large amount of 1/0 XHHW-2 wire that I could pick up cheap. If I ran 3-1/0 lines and a #2 for a ground and match that with Ser on the inside run would that work for the 90amp sub? Also I believe that would fit in 1 1/2” conduit.

 

[6togo]

Ok so the guy sold the wire before I got to it! Is voltage drop rated on the max load of your total amps? So If I have a 90amp breaker and use #2 MHF at 180' voltage drop is 4% is that with a 90 amp load or all the time?

 

[mike93lx]

Voltage drop is proportionate to load. Doesn't matter what the breaker size is.

 

[6togo]

So the lower the load the lower the drop correct? If I were to run a larger wire from the sub panel inside the garage then to a junction box and convert to #2 MHF for the 130'ish run underground would that affect the voltage drop?

 

[mike93lx]

So the lower the load the lower the drop correct? If I were to run a larger wire from the sub panel inside the garage then to a junction box and convert to #2 MHF for the 130'ish run underground would that affect the voltage drop?

You would calc voltage drop to the j box, then use that voltage as the starting point for the calc on the second section

 

[6togo]

Ok so main to #1 sub has 2-2-4-6 then 35-40' to J box I run SER then the remainder to the #2 sub in 2-2-2-4 MHF. Does it help me to upsize the SER or stay with a similar size of what's there? The #2 looks like just under 3% volt drop for the 130' run just don't know how the other portion works and if changing the neutral sizing matters allot here.

 

[6togo]

I think I'm going to run conduit from panel to panel to eliminate a JB and connection point. Probably close to the same cost as with SER. Would I be better just buying individual #2 XHHW-2 or #2 MHF for pulling?

 

[pattenp]

Use XHHW-2, you don’t need the added thickness and stiffness of MHF being direct bury.

 

[Sumboodie]

Why are there like 7 or 8 posts in a row with single questions?

 

[mike93lx]

Why are there like 7 or 8 posts in a row with single questions?

To annoy you.

Or because the guy is trying to learn?

 

[mike93lx]

Ok so main to #1 sub has 2-2-4-6 then 35-40' to J box I run SER then the remainder to the #2 sub in 2-2-2-4 MHF. Does it help me to upsize the SER or stay with a similar size of what's there? The #2 looks like just under 3% volt drop for the 130' run just don't know how the other portion works and if changing the neutral sizing matters allot here.

An upsize anywhere in the run helps with voltage drop, to some extent.

Neutral sizing won't matter unless your 120v loads will be really large or unbalanced between the legs

 

[nadogail]

The electrician who uses undersized wire has a fool for a customer.

 

[6togo]

I played around with the drop calculators and it looks like it takes a load of around 75amps before I cross 3% with #2 wire and at 90amp full load it's 3.88% for the total run. So I thinks #2 is is fine the whole distance. XHHW-2 is legal to pass through interiors in conduit correct?