I need to replace the transformer for my door bell and I have some questions on good wiring practices.
The existing (defective) transformer is attached to a metal junction box in the middle of a cable whose primary duty seems to be providing power to the furnace fan motor. There is also a porcelain light bulb socket (luminaire seems too fancy a word for this fixture) attached directly to the 'broad' face of the junction box. This house is 40 years old so who knows what's been done around the wiring, I've had surprises before.
I expect that when I lock out the breaker and open the junction box there will be 4 black wires on one wire nut (1 black wire coming in, 1 black wire going out, 1 black wire for the luminaire, and 1 black wire to existing transformer), 4 white wires on another wire nut (similar distribution as for black wires), and 3 grounds on a third wire nut (same as before except that the porcelain luminaire likely isn't grounded) or else attached to the metal box.
Is this a realistic assumption for a properly designed connection?
The reason I ask is that I had a another set of assumptions for a similar junction box that was on a switched circuit. Here the reality didn't match my preconceived notions; instead the white wire from the bathroom ventilator fan was attached to a sloppy-looking birds nest of ground wires; and that's the only way it would work.
Also, is it all right to connect 4 wires with one wire nut? Information from Ideal shows UL listed wire combinations for number/size of conductors for each model number of Wire-Nut(R), so presumably this is okay. But is this commonly done as good practice and relatively safe? Would it be better to pigtail off so that I have 3 conductors under one wire nut with the pigtail connecting the existing light and the replacement transformer with another wire nut?
thanks!