twin breakers - just as good as full size?

Status
Not open for further replies.
Coppersmith

Coppersmith

Senior Member
Location
Tampa, FL, USA
Occupation
Electrical Contractor
Can anybody point to some documentation concerning whether twin breakers are as safe and effective as full sized breakers? I've always been leery of them, but I don't know if that is justified.
 
petersonra said:
they are UL listed. that is good enough for me.
Click to expand...
I suppose that if twins each have the same wattage dissipated by the thermal element at full load as singles do you might overheat an older panel if you fill it with fully loaded twins.
Very unlikely, and the biggest bad effect would be nuisance tripping, not a safety issue.
 
I avoid them as much as possible, personally.

When I see a new panel installed with twins, I automatically think someone made a mistake.

From purely an electrical standpoint, if the panel is rated for them, there is nothing wrong with it. I however would be concerned if I was installing heavily loaded circuits onto twins just due to the potential heat buildup that may cause tripping issues.
 
Nothing worse then an older panel, back when they were narrower then most are today, and it is filled with tandem/twins in every space - especially non-CTL's that fit in any space. No wiring room left in those and worse yet is neutral bars are usually overfilled also.
 
Cow said:
I avoid them as much as possible, personally.
Click to expand...
If I see tandems in a panel, the first thing I do is verify off the panel labeling that the tandem position is shown as capable of having a tandem. If the labeling supports the use at the specific position, there is nothing more to say. It's OK.

That said, the mis-application of tandems is something I see almost as often as putting grounding type receptacles on non-GFCI ungrounded wiring methods to make them look better. At a minimum, I inform my client, and, if the scope of my work allows, I will be sure to correct the situation.

In all my years, I have replaced, maybe, two or three that were failing, and those were mostly caused by terminal lugs overheating, not the breaker itself.
 
I'm unsure why people don't like twin CB's. They're tested and listed just like full size CB's. I admit I prefer the full size ones but in practice there is no real difference other than the physical size.
 
I don't like them because the panels are smaller and the wires get all jammed up in there, especially the old panels
 
Dennis Alwon said:
I don't like them because the panels are smaller and the wires get all jammed up in there, especially the old panels
Click to expand...
The use of tandems is not restricted to panels with less volume.

I have observed them used in virtually all panel configurations from old to fresh off the store shelf.
 
al hildenbrand said:
The use of tandems is not restricted to panels with less volume.

I have observed them used in virtually all panel configurations from old to fresh off the store shelf.
Click to expand...
True, but you never see any in "bolt on" style panelboards either. Would occasionally be handy in a 480/277 panel also.:cool:

Tandems were to be expected in mobile and manufactured homes over the years - even back when typical loadcenters were narrower. His point as well as my mentioning of it earlier is that there isn't much room in those to begin with then they pack even more circuits into them by using tandems.

If I see tandems in a panel, the first thing I do is verify off the panel labeling that the tandem position is shown as capable of having a tandem.
Click to expand...
Unless it is non-CTL it shouldn't fit there (except for Eaton's CH series, they fit but are not as secure) unless something has been modified to allow it to fit.
 
UL listed and they fit, what else is there to worry about?
 
kwired said:
The need for AFCI ;)
Click to expand...
that's an RFE, request feature enhancement.
i might also say, the need for PF display right on the ocpd edge. wouldnt that be futuristic.
 
Status
Not open for further replies.
Top