6-12 panel with 8 spaces?

NoSprk · Mar 1, 2026

found a deal on this panel locally brand new with the extra ground bar but im confused.
it says its a 6space 12circut panel but has 8 knock out spaces for breakers. can someone explain to me how that works?

QO 12 Circuit Indoor Main Lug Load Center, 6 Space, 120/240V w/ Surface Mount Cover (100A)

my shop has two 8awg wires coming in so 80amps. (main box at house has 2 40amp breakers)
the 240v compressor uses 21amp and my inverter MP 180i lincoln welder says it only needs a 20amp even on 240v.
the plan is to have 2 30amp 240v breakers and hopefully have space for 4 more 20amp 120v breakers.
25x25 shop. one for each side of the shop for normal stuff, one for lighting only and one for a few outlets that are outside.

this one i was previously going to buy seems a bit overkill

Load Center, QO, 12 Spaces, 125A, 120/240V AC, Main Lug, 1 Phase

thank you for any help

mike93lx · Mar 1, 2026

Pic would help.

Guessing it has the same cover as an 8 space version

NoSprk · Mar 1, 2026

mike93lx said:
Pic would help.

Guessing it has the same cover as an 8 space version

damnit sorry. i forgot to add in the link. updated the post

https://www.supplyhouse.com/Square-D-QO612L100DS-QO-12-Circuit-Indoor-Main-Lug-Load-Center-6-Space-120-240V-w-Surface-Mount-Cover-100A?utm_source=google_ad&utm_medium=Shopping_Electrical&utm_campaign=Shopping_X_Electrical_X_SSC_Hybrid&utm_campaignid=22399310339&utm_adgroupid=177715050215&utm_targetid=pla-2465212573324&utm_product_id=QO612L100DS&utm_matchtype=&utm_keyword=&utm_adtype=pla&utm_category=Electrical&gad_source=1&gad_campaignid=22399310339&gbraid=0AAAAAD_WAytY9pXVJaIN6CNgoh-JhYuI2&gclid=Cj0KCQiA5I_NBhDVARIsAOrqIsY-7x50K5hRahqvH43f3s6--AxvDSIss2UsFXQA7febONO4Fm7h2rYaAsYeEALw_wcB

The Cobbler · Mar 1, 2026

NoSprk said:
a 6space 12circut panel but has 8 knock out spaces for breakers. can someone explain to me how that works?

it has slots for 6 breakers . the breakers can be dual circuit for single slot making 12 circuits . the cover panel is using an 8 space panel cover . the 2 outer slots are redundant

Codyboy · Mar 1, 2026

8awg and 80 amps?
Ok.

NoSprk · Mar 1, 2026

Codyboy said:
8awg and 80 amps?
Ok.

two 8awg should be rated for 40amps each correct?

PCustoms · Mar 1, 2026

2 spaces are marked do not use

PCustoms · Mar 1, 2026

NoSprk said:
two 8awg should be rated for 40amps each correct?

You probably have 240v 40 amps from the house...

Post a pic of that breaker.

NoSprk · Mar 1, 2026

Codyboy said:
8awg and 80 amps?
Ok.

the breaker for my garage has a double 40amp. the wiring coming into the garage is listed 8awg on all 3.

NoSprk · Mar 1, 2026

PCustoms said:
You probably have 240v 40 amps from the house...

Post a pic of that breaker.

yes its a 40amp tandem breaker. everything is zinsco. im going to update the garage myself and pay a professional to do the main one on the house

Codyboy · Mar 1, 2026

NoSprk said:
the breaker for my garage has a double 40amp. the wiring coming into the garage is listed 8awg on all 3.

Thats 40 amps. Not 80.

The Cobbler · Mar 1, 2026

so you have 2 legs of 40 amp , not 80 amp

PCustoms · Mar 1, 2026

NoSprk said:
yes its a 40amp tandem breaker. everything is zinsco. im going to update the garage myself and pay a professional to do the main one on the house

Hope you're replacing that.

I assume garage is detached?

Is wire in conduit? How far?

Codyboy · Mar 1, 2026

NoSprk said:
yes its a 40amp tandem breaker. everything is zinsco. im going to update the garage myself and pay a professional to do the main one on the house

Ooof.
40 amps of Zinsco would be rated at about 400 amps.
Because it'll probably take that much load to trip it or will just be enough amperage to burn it in the clear. Well along with the house too.

NoSprk · Mar 1, 2026

PCustoms said:
Hope you're replacing that.

I assume garage is detached?

Is wire in conduit? How far?

yes im replacing the zinsco stuff. detached. 50ft away in pvc pipe. buried.

PCustoms · Mar 1, 2026

NoSprk said:
yes im replacing the zinsco stuff. detached. 50ft away in pvc pipe. buried.

Theoretically easy to pull new wire.

Do you currently have 3 or 4 wires feeding garage?

NoSprk · Mar 1, 2026

PCustoms said:
Theoretically easy to pull new wire.

Do you currently have 3 or 4 wires feeding garage?

i think 3. problem is my dad added onto the house so there is about 25 ft of wire from the panel in front to the back then a connection from the back of the house to the garage so i doubt id be able to pull in the new wire from the main panel to the back of the house. my dad use to run a 80gallon compressor and big miller stick welder without issues for 20plus years. hes no longer around to ask.

mm08822 · Mar 1, 2026

A 6/12 panel could use an 8 space cover. Same for other size panels.

Mfr's way of reducing mfg part inventory. (Also hoping you need blank filler plates at $9 a bag.)

I looked at a job to put in an EV recept and panel had "4 empty slots" ( 2/column.) Took cover off (luckily) and no spares or tandem capability. Now changing out the panel guts b/c builder saved $10 15 years ago.

PCustoms · Mar 1, 2026

mm08822 said:
Mfr's way of reducing mfg part inventory. (Also hoping you need blank filler plates at $9 a bag.)

Mild hijacking, why the hell are those so expensive? Needed 2 a while back and the smallest double pole breaker was the cheaper option to fill the hole...

mm08822 · Mar 1, 2026

PCustoms said:
Mild hijacking, why the hell are those so expensive? Needed 2 a while back and the smallest double pole breaker was the cheaper option to fill the hole...

As long as there is a buss behind the open slot put cbs in. Best chance of using your dead money otherwise lost in the panel.

sparky 1971 · Mar 1, 2026

Square D specializes in using one cover for several different panels. I've fallen for the 20 space cover on a full 16 space panel thinking there was space available to add another circuit more than once. I'm sure other manufacturers do the same thing but I don't recall ever running across another brand.

wyliesdiesels · Mar 2, 2026

NoSprk said:
found a deal on this panel locally brand new with the extra ground bar but im confused.
it says its a 6space 12circut panel but has 8 knock out spaces for breakers. can someone explain to me how that works?

QO 12 Circuit Indoor Main Lug Load Center, 6 Space, 120/240V w/ Surface Mount Cover (100A)

If you look at the guts, you will see there is a lug in the way of that #8 space on the right. also the diagram says not to use that space or the one on the left. as said above, theyre using a cover from a larger panel.

NoSprk said:
my shop has two 8awg wires coming in so 80amps. (main box at house has 2 40amp breakers)

If #8 cu THWN it is good for 50a but someone used a 40a breaker. you dont add up the breakers to get 80a (or 100a).... its a 40a 240v circuit

wyliesdiesels · Mar 2, 2026

NoSprk said:
i think 3. problem is my dad added onto the house so there is about 25 ft of wire from the panel in front to the back then a connection from the back of the house to the garage so i doubt id be able to pull in the new wire from the main panel to the back of the house. my dad use to run a 80gallon compressor and big miller stick welder without issues for 20plus years. hes no longer around to ask.

you need 4 wires- 2 hots neutral and ground. since this is a new install of a panel, you should update the feeder.

6-12 panel with 8 spaces?

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