main panel to sub panel wiring

[F3RR3T]

Ok well i just upgraded the service in the house from 100amp to 200amp and replaced the main box and all the breakers. (let me know how i did)

Anyway i want to run all my tools in the shop off a 100amp sub panel. Well as you can see i have no where to put a 100 amp breaker. So i was wondering if i can tap the mane buss bars in the panels (where the green arrows are in my picture) with some copper terminals, and run my 4awg from my panel from there.

 

[LoneGunman]

Buy four tandem breakers, that will give you the two open spaces you need.

 

[Charles (in GA)]

Should have bought a 40/40 panel instead of a 30/40 panel. The panel will have some special slots for tandem breakers (or possibly any space is OK, depends on the panel).

But yes, replace two of the breakers with two tandems, and the two full width slots you need will open up. Looks like you need to do this at the bottom.

Panel is not designed to be tapped at the point you are indicating, and if you did, you would have to use heavier cable (4/0 aluminum or 3/0 copper) as the only thing protecting the subfeed would be the 200 amp main breaker. cannot use undersized wire.

The 4 gauge (copper I assume) you propose to use is not suited for 100 amps.

Charles

 

[StumpFJ40]

This seems to be my standard contribution lately: Take a look at the panel door, it often has a schematic that shows where on the panel you can put the tandem breakers (they allow you to put two circuits in the space of one breaker).
Yep, I've learned just enough to be dangerous

 

[Aceman]

You need to get rid of that 2 pole Homeline breaker and put a Siemens in. I see one white wire on a breaker that's not reidentifed. Other than that, looks good.

I would of bought a 40/40 panel in your case. I hate using twin breakers on a new install.

 

[F3RR3T]

went and got 2 tandem breakers, and 4 awg should be fine to run 100 amp sub-panel correct the wire run is only 3 feet

 

[mrb]

went and got 2 tandem breakers, and 4 awg should be fine to run 100 amp sub-panel correct the wire run is only 3 feet

no. need #3 copper or #1 AL for 100a. just put your #4 (if its copper) on a 90 amp breaker. looks like you have some MWBCs in there, be careful you dont put both hots from one on the same phase when you are swapping breakers around and installing the tandems.

 

[F3RR3T]

no. need #3 copper or #1 AL for 100a. just put your #4 (if its copper) on a 90 amp breaker. looks like you have some MWBCs in there, be careful you dont put both hots from one on the same phase when you are swapping breakers around and installing the tandems.

mwbc?
and ill just pick up some #3 copper from the borg today

 

[916matt]

mwbc?
and ill just pick up some #3 copper from the borg today

multi-wire branch circuit. one phase conductor from each phase can share a neutral. 1 a phase and 1 b phase conductor. not 2 a phase or 2 b phase