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Old 04-19-2019, 02:21 PM   #1
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How many slimline (THQP) double poles can I have?


Hi all,
I have a GE TMC4020CCU Powermark loadcenter (Canadian model) with 40 spaces. The circuit diagram indicates that it can take 80 1/2" breakers (THQP) in any position. But it then says the maximum number of 2 pole THQP breakers is 38. What I don't understand is why this number is not 40? Are there slots in the panel that won't accept 2-pole THQP breakers?
This model is the same as the GE TM4020C80 US model.

A link to the wiring diagram is included in the attachments

Thanks in advance for any help
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How many slimline (THQP) double poles can I have?-tmc4020-p1.png   How many slimline (THQP) double poles can I have?-tmc4020-p2.png  
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Old 04-20-2019, 12:02 AM   #2
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Re: How many slimline (THQP) double poles can I have?


A THQP 2 pole breaker bridges across 2 slots so on each side of the panel you lose the top and bottom 1/2 position.

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Old 04-20-2019, 05:12 AM   #3
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Re: How many slimline (THQP) double poles can I have?


Why do you need that many circuits?
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Old 04-20-2019, 06:37 AM   #4
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Thank you. That makes sense. I was looking to put a THQP double pole in the top right 1" position (slot 2). So basically I can't do that. I will need to move things around as that was my last open slot.
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Old 04-20-2019, 06:48 AM   #5
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Follow up question: do the THQP double poles all need to start on an odd 1/2" slot?
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Old 04-20-2019, 07:50 AM   #6
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Re: How many slimline (THQP) double poles can I have?


Quote:
Originally Posted by lmcancu View Post
Follow up question: do the THQP double poles all need to start on an odd 1/2" slot?
Yes. They need to bridge 2 slots so they pick up 120 volts for each pole so the output is 240. You can use single pole THQPs in the other half slots.

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Old 04-20-2019, 07:53 AM   #7
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Thank you. Finally understand now.
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Old 04-20-2019, 08:26 AM   #8
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I am assuming that this is a hypothetical question. If you need 38 - 240 volt circuits, you need more than a 200 amp panel and not use crappy thin breakers. I know this is not the case.
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Old 04-25-2019, 07:50 PM   #9
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It was more to try to understand in which positions I could add the thin THQP 2 pole breaker. My panel is full except for slot 2. I currently have 2 THQP breakers. One 30 amp and one 20 amp. I plan to replace 2 standard 30 amp breakers with 2 slim 30 amp breakers to make room for 2 slots.
Do these THQP breakers have a bad reputation? I have never had any issues with the 2 I have.
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Old 04-26-2019, 05:52 AM   #10
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Re: How many slimline (THQP) double poles can I have?


Install the 2 pole in the bottom of slot 2 and top of slot 4. Fill the remaining half spaces with single poles.

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Old 04-26-2019, 07:24 AM   #11
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Re: How many slimline (THQP) double poles can I have?


My experience with 1/2 size breakers is, that over time, their inability to dissipate heat causes problems such as breaker failure. Before you install too many, consider a sub panel.
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Old 04-26-2019, 08:15 AM   #12
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Re: How many slimline (THQP) double poles can I have?


Quote:
Originally Posted by Let it Snow View Post
My experience with 1/2 size breakers is, that over time, their inability to dissipate heat causes problems such as breaker failure. Before you install too many, consider a sub panel.
I have some GE THQP (half slot sized) breakers in my main panel that have been there since the house was built 31 years ago. I have rearranged a few with some changes I have made. Never an issue but I will admit I keep them on lightly loaded circuits.
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