Connecting white and red reverses the phase of ONE winding.
Since you measured zero volts with white and yellow connected (that confirms that the two windings were "out of phase"), you should now get the "double voltage" reading.
Yes you can connect the other pair of leads. You will again get double voltage when in phase and zero voltage when out of phase.
If your meter is wavering, either it is faulty, or you are still being troubled with partially insulated leads.
The best way, that I find works, is to insert all the leads into separate receptacles of an insulated terminal block. The screws deform the solid core copper and break through the varnish guaranteeing a good electrical connection (for low current duty).
The second advantage is that all the dangerous wire ends are now insulated !!!!!!!! and thirdly, are physically constrained so that they can't spring up and catch you unawares while trying to take a measurement.
Learn to adopt safe practice when working with Mains Power. Learn to recognise risky procedure and develop safer methods.
One is keep kids and pets out of the room where you are working.
Another is to have a supervising eye over your shoulder, they could switch off power if there is a calamity, or shout STOP, if you are about to do something daft.
I rarely have anyone else around when working, that alone increases my risks.
I did once have an electrician neighbour arrive while I was wiring up the three way switching of some wall mounted lamps.
He saw and asked "what are you doing?"
He had instantly recognised that I was misusing the yellow wire !
Since you measured zero volts with white and yellow connected (that confirms that the two windings were "out of phase"), you should now get the "double voltage" reading.
Yes you can connect the other pair of leads. You will again get double voltage when in phase and zero voltage when out of phase.
If your meter is wavering, either it is faulty, or you are still being troubled with partially insulated leads.
The best way, that I find works, is to insert all the leads into separate receptacles of an insulated terminal block. The screws deform the solid core copper and break through the varnish guaranteeing a good electrical connection (for low current duty).
The second advantage is that all the dangerous wire ends are now insulated !!!!!!!! and thirdly, are physically constrained so that they can't spring up and catch you unawares while trying to take a measurement.
Learn to adopt safe practice when working with Mains Power. Learn to recognise risky procedure and develop safer methods.
One is keep kids and pets out of the room where you are working.
Another is to have a supervising eye over your shoulder, they could switch off power if there is a calamity, or shout STOP, if you are about to do something daft.
I rarely have anyone else around when working, that alone increases my risks.
I did once have an electrician neighbour arrive while I was wiring up the three way switching of some wall mounted lamps.
He saw and asked "what are you doing?"
He had instantly recognised that I was misusing the yellow wire !
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Hi Andrew, you are right, safety first and thanks for your concern. I rather ask stupid questions than blow up sth. That's why also the stuff about internal structure of transformers, because I want to inform myself. A black box when it comes to transformers is not like a black box with opamps.
My mains test setup has fuses on the live and neutral and bulb in series with the live. A double switch for live and neutral (not implemented yet). And I don't move anything when the mains is plugged in. The clamps are in place, voltmeter turned on, safety goggles on, and then from a distance the setup is powered on and I walk over to do the readouts only. Unplug and then if sth is not as expected I post. Maybe it's an overkill, but I am aware it's not sth one can play with. At our microscope we have a high tension source, where there is a note which says "Don't". Once I asked don't? Don't what? And got the reply, don't means - don't even think. The moment you get an idea next to the hight tension, simply stop and don't
Btw I've seen your post about amateurs need protection like the bulb tester not professionals and yes one has to be extremely careful. I am an amateur with capital A and it's simply dangerous and there is no room for error here. I am not aiming at getting a Darwin award anytime soon.
Martin
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