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Sub panel

7.6K views 9 replies 4 participants last post by  wolverines57  
#1 ·
100amp panel that feeds a service panel for 1st floor apartment.

Question?
Is it o.k. to take a feed of the 100amp panel to a small sub panel 30amp 240volt to run a clothes dryer in the basement. Plan on using 10/3 from 100amp panel to 30amp sub panel then 10/3 to 240v outlet.
Many Thanks
 
#3 · (Edited)
Yes! My fault, let me clarify.
In the basement 100amp panel [no slots] feeeding small (room for two breakers) sub panel adjacent to it; in the sub panel is a 15amp breaker [oil furnace] and a vacant slot [ I'll come back to the vacancy soon ]. Connected with 10/3.

The 100amp panel is also feeding the first floor service panel, all slots taken.

They want a clothes dryer, first floor service panel is full: So I was going to add a 2nd sub panel [30amp 240v breaker] feeding from 100amp panel in basement for the dryer.

But, just discovered the sub panel with vacant slot is a D model and D makes a single 30A 240v breaker, so life just got easier. Unless you disagree?

The only thing I'm not sure about is if I replace the 10/3 with 8/3 [short run 9inches] will that be sufficient for 30A 240v and a 15A 120V?
I know they recommend 40amps max for 8/3, can I let the 5amps slide [or is this the slippery slope].

Hi, Speedy, I mainly do renovations in the New Paltz area, good sparkies are hard to come by. Are you in the book?

Many thanks. Hope its clear.
 
#4 ·
mjay said:
They want a clothes dryer, first floor service panel is full: So I was going to add a 2nd sub panel [30amp 240v breaker] feeding from 100amp panel in basement for the dryer.
This is where I get confused. If all the slots are full how are you going to feed the new panel?


mjay said:
But, just discovered the sub panel with vacant slot is a D model and D makes a single 30A 240v breaker, so life just got easier. Unless you disagree?
What is a "D model"? Do you mean Square D? If so then one slot does you no good. You cannot get 240v from one slot.




mjay said:
The only thing I'm not sure about is if I replace the 10/3 with 8/3 [short run 9inches] will that be sufficient for 30A 240v and a 15A 120V?
I know they recommend 40amps max for 8/3, can I let the 5amps slide [or is this the slippery slope].
The breaker amperage is not cumulative. So 30 plus 15 does not necessarily equal 45.


I think your best bet is to see if one of the panels will accept twin (or skinny) breakers. You can use them to move some single pole circuits so you can fit a two-pole breaker in. The only thing is will your panels accept twins. The label will tell you. Let us know what the label says if you are not sure.
I would also look closely at the demand load.
Are you overloading the service by installing this dryer?
How big is this place?
How many people living there?
What applainces/other electrical loads are there?
Etc....



mjay said:
Hi, Speedy, I mainly do renovations in the New Paltz area, good sparkies are hard to come by. Are you in the book?
Actually I'm not, and I like it that way. :whistling
I'm only about half hour/40 min. north of you. I really don't get down there at all. I am swamped just staying local.
I'm doing a job in High Falls right now, but only as a favor to the contractors who are good friends of mine.


Let me/us know what you come up with about your situation.
 
#5 · (Edited)
Thanks for the help Speedy, yes square D is the manufacturer.
That's good news about the amp ratings.

QO130 MINIATURE CIRCUIT BREAKER 240V 30A, lead me down the garden path.
I only have one spare slot in their sub panel, so I'm going to upgrade their sub panel. The sub panel draws directly from the 100amp panel via 10/3 not the service panel.

I'll be checking their upstair's sevice panel, its two people, propane stove, oil heat. It would be nice to upgrade to 200A service, but they are renting and would probably rather loose a few luxuries [A/C in the summer] than pay for the upgrade.

Do you like seeing this side if the Gunks?
Thanks again for the help.
 
#7 ·
Breaking the Law!
No, not a licensed electrician. They're friends and no money is changing hands, I'm replacing a sub panel.
Perrmits required to replace a sub panel?

Replacing a sub panel that has 2 breaker slots for a sub panel with 6 breaker slots, so they can run a dryer. Service panel [1st floor] is fed by 100amp main breaker in basement. Current sub panel is used to feed oil burner: 10/3 feeder cable between 100amp main breaker and sub panel.

I know enough to make me dangerous, that's why I ask questions, research, and seek advice.
Many Thanks