I have a residential panel with all Challenger circuit breakers with the exception of a single GE breaker. Challengers say Type C115 and GE says 15A. Can you tell me if these are compatible?

In a traditional North American residential electrical panel (120/240 volt, single phase), installing a single width or single pole circuit breaker, you would expect to read 120 volts from the breaker terminal screw to either ground or neutral. A double width or double pole breaker would provide 120 volts from either of the breaker terminal screws to ground or neutral AND it will provide 240 volts BETWEEN the TWO breaker terminals.

A single-width circuit breaker case that contains two handles is NOT a two pole circuit breaker (these are called "tandem" or "1/2 size" breakers). This is because a single width breaker engages only one "line" in the panel. A double width breaker will engage 2 "lines" as a triple width breaker would engage 3 "lines" of a 3 phase panel. A single wide breaker can not physically engage more than 1 "line" so it will never be able to pass 240 volts.

You must install a double width / double pole breaker to safely supply a 240 volt circuit / device.

It appears that Siemans, Murray, Eaton, and Square D are compatible. Look for those brands with "1515" in the part number, such as MP1515, Q1515, BR1515, HOMT1515. Challenger is presume\ably no longer in business.

The National Electrical Code prohibits the use of mixing circuit breaker manufacturers and circuit breaker panels by requiring all electrical equipment to be certified (UL Listed, FM, etc.). Challenger breakers are UL listed, as are Challenger panels. All the circuit breakers installed must be made by Challenger and must be approved for use in that particular panel (more on this below). Installing a different brand breaker into the panel causes the panel and the breaker to lose the UL / FM listing. The lack of a listing causes the electrical code violation. Should a fire occur, and the source is determined to be the use of a mixed manufacturer panel / circuit breaker installation, you insurance company may balk at paying a claim.

If you are unsure of the circuit breakers that are approved for use in your panel, look on the inside cover of the door. On it should be listed the manufacturer's name and all the devices that that the panel will accept. Deviating from the list will trigger the loss of listing.

A final thought: Most GFI breakers are much more expensive than a GFCI outlet. Install a standard non-GFI Challenger breaker and feed a new outlet (next to the panel) with a GFCI plug via the LINE terminals. Connect the rest of the old circuit to the outlet's LOAD terminals. The portion of the circuit that is connected to the LOAD terminals are now GFCI protected. Overloads will trip the circuit breaker as usual, but ground fault issues will trip at the outlet instead.

I hope this helps and good luck! Please rate my reply. thanks.

You can still get Challenger breakers. Here is a website that sells them...

http://www.pacificcoastbreaker.com/page.home

Turn off the main. Carefully remove the cover (held on by 4 corner screws) --- the fat wires coming in to the main will be exposed and they are very much LIVE. Remove the wire on the existing breaker by loosening the screw and pulling out the end of the wire. The end of the breaker that held the wire just pulls out. The other end of the breaker is held under a hook that will easily disengage. Replacement is reverse of removal. BE VERY CAREFUL OF THE WIRES AT THE TOP GOING TO THE MAIN. If you are not sure what the main is, or you don't know what I mean by the wires going into the main, then DO NOT ATTEMPT THIS REPAIR YOURSELF!

THQL-1115 This is a 15 amp single-pole circuit breaker for the Powermark load center,

A Challenger 20 Amp single pole breaker shouldn't be priced much different than any other brand of breaker if you buy them online and not at Home Depot. That is if it isn't the Zinsco style like these:

According to Eaton's cross reference a BR 120 will cross with a C 120. You can find the cross reference here:
http://www.eaton.com/ecm/groups/public/@pub/@eaton/@ee/documents/content/1081453631966.pdf
Lowes shows the BR 120 at 3.47

They look like these:

You can only safely use breakers listed for your panel . It will depend on the style of the challenger breaker you are using. Go by the breaker number you currently have and it may cross over to a different brand with same part number . There are two basic Challenger styles. The Zinco/Westinghoue/Challenger Long skinny Like thi one.
and the Murry/Bryant style like this Siemens breaker

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While there is a practical limit for the number of outlets on a 15 or 20 amp general purpose lighting circuit in a _residence_, the National Electric Code (NEC) does not impose a # of outlets per circuit limit (residential ONLY).
However, some electrician's design general purpose lighting circuits in a residence using a point system. An outlet is 2 points and a light is 1 point. So, for a twenty amp circuit, (10 outlets x 2 points) = 20. Or, (5 outlets x 2 points) + (10 lights x 1 point) = 10 + 10 = 20. Or (8 outlets x 2 points) + (4 lights x 1 point) = 16 + 4 = 20. However you want to mix it up.

Now, if this is for a Commercial building, the the NEC allows no more than 180 VA (Volt Amps) per outlet. 180 VA / 120 Volts = 1.5 Amps.
20 amps / 1.5 Amps = 13.3 outlets. Drop the .3 and one determines that 13 outlets are allowed on a Commercial 20 amp circuit.

Also, if the 20 amp circuit is considered a continuous circuit (ON for more than 3 hours a day), then it can only be loaded to 80%. 80% of 20 amps = 16 amps.

First HACR is heating, air conditioning,refrigeration. So in other words you could use it on an electric furnace or air conditioning.
IS this the main breaker for the panel? or for and electric furnace. I'm assuming its for the furnace, perhaps back up heat for heat pump. See if there is another disconenct on the furnace, turn it off and see if the breaker resets. IF so you have a short or overload in the furnace.
If' it IS the main for the panel, turn off all the other breakers in the panel, and try to reset the breaker. If that works, turn the other breakers back on one at a time. IF it "POPS" then it is tripping. Don't keep resetting, find the problem.