Old QO 6 space breakers

[electrofelon]

What is with these things? I see them quite a bit in older gear. Why do they take up 6 spaces and when and why did they change to 1 space per pole? Three phase miniature breakers seem to go up to and including 100 amp now, was this not always the case? These I am talking about are NOT over 100 amp. The one in the picture is a 90. I thought maybe it was a higher AIC, but it says 10k on it.

 

[LarryFine]

To use two stabs per pole instead of one for better contact, and to make sure another breaker isn't installed opposite it.

 

[jim dungar]

These are Q1 breakers, not QO. The breaker plug on jaw used to be rated/tested for a maximum of 60A, so the 70-100A versions were built double wide.
The Q1 family was obsolete in the early 80's, when the higher ampacity QO breakers were introduced. The QO and Q1 breakers are completely interchangeable, except for the Q12100TF main breaker version which had the lugs on the 'side' of the breaker, rather than on the end, for top feed.

 

[electrofelon]

to make sure another breaker isn't installed opposite it.

These are Q1 breakers, not QO. The breaker plug on jaw used to be rated/tested for a maximum of 60A, so the 70-100A versions were built double wide.
The Q1 family was obsolete in the early 80's, when the higher ampacity QO breakers were introduced. The QO and Q1 breakers are completely interchangeable, except for the Q12100TF main breaker version which had the lugs on the 'side' of the breaker, rather than on the end, for top feed.

Ah makes sense, thanks!