No, they will not fit. You can use Westinghouse, Cutler Hammer BR series, and Connecticut Electrical UBITBC series breaker. All of those will fit.
A 100-A sub-panel would be fed from a 100-A breaker.
No, they will not work. Use only Murray breakers for safety.
In North America a two pole breaker will be used in the distribution panel for a supply of 240 volts for a 240 volt load.
A QP type breaker is made by Siemens for a Siemens distribution panel and should not be interchanged with Square D. A Siemens QP type bolt in breaker will bolt into a SQ distribution panel but it is up to the electrical inspector to make the call as to it being safe or not. Square D breaker types are QO and QB. You might be mistaking the QP for a QB on the breaker. The QO breaker is a plug in breaker usually used in home wiring and the QB is a bolt in breaker. QB breakers are usually specified for industrial and commercial use.
Use a 30 amp breaker.
A Murray or similar breaker would work but most inspectors want the brand breaker to match the brand panel.
To answer this question the type of breaker you want to exchange needs to be stated, bolt in or plug in.
A 100-A sub-panel would be fed from a 100-A breaker.
No, they will not work. Use only Murray breakers for safety.
Legally, you must use the same brand breaker with the brand panel. They sell Murray breakers at your area electrical contractor shop, but used I am sure. However, square d homeline, siemens ite, GE, cutler hammer BR do fit but will void the UL listing and are dangerous to mix. Upgrade your panelboard. It is old.
In my experience, NOTHING is compatible with a Murray panel. Others claim there are certain Siemens and Federal Pacific breakers or Eaton type "CL", but you might have to obtain permission from the inspector to use anything other than Murray.
To be short...Yes
Yes.Additional InformationBreakers and fuses protect the wires to prevent fire. The 100 Amp breaker in the meter base (main) protects the wire from the meter base to the breaker panel. The 50 Amp breaker in the breaker panel protects the wire from the breaker panel to the outlet. Sometimes the 100 amp main breaker is located in the panel.If you are asking "Can you use two 50 amp breakers for the main breakers with a 100 amp service, then yes you can. The National Electrical Code allows you to use up to 6 breakers as the main overcurrent protection.
The Cutler Hammer BR series will fit and also the Connecticut Electric UBITBC series will fit your Westinghouse service panel.
In North America a two pole breaker will be used in the distribution panel for a supply of 240 volts for a 240 volt load.
A QP type breaker is made by Siemens for a Siemens distribution panel and should not be interchanged with Square D. A Siemens QP type bolt in breaker will bolt into a SQ distribution panel but it is up to the electrical inspector to make the call as to it being safe or not. Square D breaker types are QO and QB. You might be mistaking the QP for a QB on the breaker. The QO breaker is a plug in breaker usually used in home wiring and the QB is a bolt in breaker. QB breakers are usually specified for industrial and commercial use.
If there is no neutral available you cannot, unless you use an autotransformer and derive a neutral. A panel with no neutral is called a power panel and is used to supply 240 single and three phase loads.