Good pics! Anybody know when the clause in 240.81 was added?


What was the timeswitch feeding?

I've replaced some of these old SqD panels.
The breakers plugged onto the bus in a very inadequate way, and the C/B's entire sides were made of "fish paper" (insulating cardboard).
Seems to me (although I'm not sure) that they were called a type "X".

Or maybe type "XO"?

>>Pauluk: What was the timeswitch feeding?

Well my house has one and it controls the on/off times of the electric water heater. That is what I see them used most often for.

Rennsport

The Reset handles look similar to those used on Type XO frames, and the era is about right for the installation of XO equipment...

But...

The frames do not line up next to each other - and there's "Odd / Even" circuit spacing ("Left / Right"), plus a very wide space between the "Left / Right" handles, which makes me think this is something in the "A1" or type "A Block" Family.

The typical XO Bus kits I have seen (1Ø 120/240 VAC, 100 Amps Max. common Residential usage) look much like an old Zinsco Bus kit for Plug-On type "Q" frames. The Bus Bars run the length of the Bus Kit, and Breaker frames are plugged in "one behind the other" - in a single row fashion.

The Plug-On Termination clips, for the Line side connection of the C/B frame to a certain Bus Bar, can be repositioned to land on "The Closer" or "The Farther" Bus bar. This is regarding 1 Pole Frames. 2 Pole Frames have one Pole's clip set for the closer Bus, and the other Pole's clip set for the farther Bus.

(it's been awhile since I last seen XO equipment, so I may be a little off... or way off!).

The Panelboard in the Images appears (to me) like it has the "A-Block" Modular equipment (maybe that is "M-Block"???)
Again, I cannot remember the Sq. D Model of those things - they are similar to the Modular Kits made by G.E. - under the Trumbull name ("The Trumbull Electric Mfg. Co." - A General Electric Organization).

Would be nice to know what the equipment type actually is in the image...

Time to go dig up some Antique Square D Panelboards!

Scott35

By the way. This picture was taken this year. The date in the photo is wrong because I did not set the camera after adding new batteries.

Just thought you might like to know...

Rennsport

I ran into a variation of this SqD panel in a service relocation and upgrade I did some time back. The panel was the first that SqD offered for general residential use, starting in the late '30s. The breakers were factory installed. One selected from a list of breaker configurations. . .and you made the wiring fit to that.

One of the unique features is that the breakers and hot buses were mounted on an internal pan that was not as deep as the cabinet. The pan was hinged on the left side, front edge, allowing the entire bus/breaker assembly to swing forward and out.

All the neutrals were laid on the back of the cabinet (while the bus/breaker pan was out of the way) and then the hot wires were hooked up.

A SqD rep sent me copies of the advertising from the late '30s championing this design by showing a svelt lass in party dress using one finger resetting a breaker with a caption to the effect, "Never search for a fuse again!"

This system (shown in Rennsport's photos) is what the XO system came from. The big advancement with the XO was the ability for the installer to configure the panel at the site from boxes of individual breakers that plugged onto the bus.

I recently came across a house that was slated for demo that had the SqD "XO" type panel. It was the 20 space veriety... all in a single column, with each breaker installed in a left/right alternating arrangement. I estimate the house to have been built in the 1910's or 20's. The house was wired with knob & tube, but the panel had mostly paper-style NM cable entering it.

I gather this panel type is newer than the house... probably replacing an older fuse panel as part of a rewire job.

When did the XO panels appear? When did they become obsolete?

The Multibreaker, shown in the thread's photos was introduced in 1936.

The XO "plug in" type of breaker was introduced in 1951.

Interestingly, just four years later, in 1955, the QO line of breakers was introduced.

This information comes from [b]A Timeline from Square D's Web Site[/b]

I had contacted Square D awhile ago about permission to post some of their photos here.

........ No answer yet,
but I did get a call from them last week about it.

Bill

The Square D panelboard shown in the photo is type MO. The two-pole breakers were for the electric range and the hot water heater. The single-pole breakers were for lighting and receptacles. We had exactly this panel in my parents' home which was built in 1941. Type XO, which was available from both Square D and Cutler-Hammer was a commercial unit which I saw in gas stations. There were two vertical straight busses in the panel. The breakers had two clips in the back, one was live and one was a dummy. The electrician balanced the load by alterating the breakers -- breaker 1 to bus 1, breaker 2 to bus 2, breaker 3 to bus 1, etc. Thus the breakers operated on opposite directions. They had very limited life and could not be used for switching. It was a long time before the SWD-rated breakers appeared. Before then we used a row of toggle switches below the panel for switching lights at the pump islands, etc.