Panel spec- 20/40, space/circuit , question

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sw_ross

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The spec of 20 space/40 circuit as compared to 20 space/20 circuit panel kind of confuses me.
Both are physically the same size. Does the 40 circuit (versus 20 circuit) allow a full panel of “twins”?
is the buss heavier to allow for more circuits?
They are both rated for 100 amps. What’s the difference?
A very basic question that has confused me for a while.
 
sw_ross said:
Does the 40 circuit (versus 20 circuit) allow a full panel of “twins”?
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Yes.

is the buss heavier to allow for more circuits?
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No. The total current would be the same as a 40 sp/40 ckt panel.

They are both rated for 100 amps. What’s the difference?
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The bus is designed to accept tandems.
 
LarryFine said:
Yes.

No. The total current would be the same as a 40 sp/40 ckt panel.

The bus is designed to accept tandems.
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But 40 only if no AFCI or GFCI breakers, no tandem for those yet, that I've seen. Siemens claims to have one but haven't seen it.
 
I just installed a BR 30/60 panel yesterday and it did not have notches in the fuss. It was 100% exactly like the supposed non CTL panel.

I was completely surprised, and very thankful I have a whole box full of non CTL twins, both 15 and 20

I haven't taken pictures of it because I'm not finished working in it, but when I go back on Tuesday I'll have some.

Having typed that, now watch me get back Tuesday and it'll be a case where somebody swapped out that panel in the box 🙄

😅😅😅
 
Depending on how grounds are dealt with, a 20/20 panel will have about 20 neutral bus positions. A 20/40 ought to have close to 40. I have a 30/40 main service panel and it is short on neutral lug space. If I could untangle all the grounds I could triple up some of them. But I'm just going to rip it out and do it all over. New panel will be 32/64 with hardly any twins because most things need AFCI now (will have a separate panel for all the double poles and a few more circuits since I actually need 40 to 50 slots). Should never have a neutral lug issue in that panel or the new main one again.
 
suemarkp said:
Depending on how grounds are dealt with, a 20/20 panel will have about 20 neutral bus positions. A 20/40 ought to have close to 40. I have a 30/40 main service panel and it is short on neutral lug space. If I could untangle all the grounds I could triple up some of them. But I'm just going to rip it out and do it all over. New panel will be 32/64 with hardly any twins because most things need AFCI now (will have a separate panel for all the double poles and a few more circuits since I actually need 40 to 50 slots). Should never have a neutral lug issue in that panel or the new main one again.
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I have never understood why they make a panel that's supposedly good for 30 circuits, and I get 16-20 spaces in the neutral bar. 40 circuit panel and you get about 28 neutral bar spaces
🙄

But I guess that's getting better with the plug on neutral breakers.
 
James L said:
I have never understood why they make a panel that's supposedly good for 30 circuits, and I get 16-20 spaces in the neutral bar. 40 circuit panel and you get about 28 neutral bar spaces
🙄

But I guess that's getting better with the plug on neutral breakers.
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Because there was a day when competent electricians knew how to wire circuits using MWBC and were not afraid to.
 
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