If this double-tap arrangement is wrong, and it can’t be right to use stranded and solid wire under one screw, can it? 
Could this be fixed with a pigtail and a wire nut? How is this done professionally?
(Yes, this is a Canadian Federal Pioneer panel, fairly new.)
John Kogel
www.allsafehome.ca
Professionally you would install a separate breaker.
As far as I know, Federal Pioneer breakers are still rated for only one conductor under the breaker’s terminal. What you have pictured is non-compliant, in my professional opinion. I do disagree, however, that the corrective measure is to dedicate a circuit to the chime transformer. That would be absurd, or wasteful at least. The real corrective action normally involves pigtailing a single conductor to the breaker and making a wirenut splice in the panel. Oops! Sorry. Canada here… a ‘marette’ splice.
Tres bien, Marc. Les marette s’appelle “wire-nuts” aussi.
My step-dad gave me a whole box of old timer “marettes” that were threaded brass rings with setscrews and plastic caps that screwed down over them, boy what a pain to wire a house with those! The electrician had a good laugh when he came to install the service.
I can think of another way to install the tranformer - to attach it to a handy junction box in the garage or the attic. Easier to replace that way.
Actually, if you see a chime transformer in the attic, chances are pretty good you’re looking at an improperly installed chime transformer. While it has not always been the case, for the last 10-15 years they’ve had a maximum ambient temperature limitation, with a notation in the instructions to not install them in the attic. I recently finished rewiring an apartment building, and there was no good place in the tenant space to put each chime transformer. I ended up mounting each one on the end of the 2 foot fluorescent strip light that was mounted inside each entry hall closet, above the door header. Pretty much hidden that way.
**Splices and Taps. ****No unnecessary splices or taps shall be made within or on a luminaire. **
[size=1]FPN: For approved means of making connections, see 110.14.
[/size]
This one was necessary. It was determined by me that it was necessary in order to make the chime transformer mounted on the end of the strip light function. In much the same manner that some luminaires contain the option to remove a 1" square knockout to install a receptacle or a small round knockout to install a canopy switch. Those connections are necessary too. That code section is so vague that it has no teeth to use for enforcement.