Lighting Transformer

[NickParker]

Can single phase transformer be mounted inside the MCC (as per IEC) for small loads such as lighting, Heating and Damper loads. As per North American standards, single phase transformer for distribution cannot be mounted inside the MCC or LV switchgear? Can I know why it can't be mounted inside the MCC?
Why there is a separate transformer for lighting? why cant the normal Low voltage transformer be used for lighting?

 

[farale]

lighting circuits & fixtures are major sources of single phase short circuits.
to isolate such faults from rest of the power system, isolating transformers (also known as lighting transformer) are used.
the provide complete isolation between primary and secondary circuits. in addition, due to their Uk% (mostly about 4%) they reduce short circuit level on the lighting circuits.
most used type of transformers for lighting system is dry type, which is allowed to be installed inside the substation, but out of the MCC of course.
oil type xformers cannot be installed in the buildings because of risk of explosion.

 

[rcw retired EE]

We have installed many MCC's with lighting and control power transformers. Size is limited to about 45 kVA due to space restrictions.
Our philosophy is to always put lighting circuits on a separate panel than other 120V loads, especially critical process control power. We had too many trips by someone toggling breakers in a common panel and shutting down a process.