# Need to replace doorbell transformer attached to electrical panel



## Nealtw (Jun 22, 2017)

You want to try the pictures again.


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## CodeMatters (Aug 16, 2017)

Nothing to it. Just make sure the new one is the same voltage and mounts 
in the same way which is likely in 1/2" knockout. After that, just swap 
all 4 wires, wire for wire. Polarity doesn't matter. 
I do it it live, but go with what you're comfortable with.


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## jdraganescu (Nov 12, 2008)

jdraganescu said:


> Hi everyone,
> 
> I need to upgrade my doorbell transformer from 16 V 10 VA to 16 VA, and I have just discovered my doorbell transformer is attached to the lower left side of one of my electrical panels. While I have done a number of electrical projects around the house, I have yet to work on any component that is physically connected to the electrical panel. I have attached photos of this arrangement, even though I know everyone reading this thread knows what I am talking about.
> 
> ...


Here are the photos.


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## jdraganescu (Nov 12, 2008)

Thanks for your reply. From your reply, it sounds like I can detach the current transformer from the panel box and then have access to the 110 VAC wire connections from outside the panel box. One question: I cannot see any mounting screws or clamps on the current transformer. How do I remove it and mount its replacement?
Thanks.


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## Nealtw (Jun 22, 2017)

jdraganescu said:


> Thanks for your reply. From your reply, it sounds like I can detach the current transformer from the panel box and then have access to the 110 VAC wire connections from outside the panel box. One question: I cannot see any mounting screws or clamps on the current transformer. How do I remove it and mount its replacement?
> Thanks.


Remove the front panel of the breaker box, if you are not comfortable doing that, you need help.


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## jdraganescu (Nov 12, 2008)

CodeMatters said:


> Nothing to it. Just make sure the new one is the same voltage and mounts
> in the same way which is likely in 1/2" knockout. After that, just swap
> all 4 wires, wire for wire. Polarity doesn't matter.
> I do it it live, but go with what you're comfortable with.


Default

Thanks for your reply. From your reply, it sounds like I can detach the current transformer from the panel box and then have access to the 110 VAC wire connections from outside the panel box. One question: I cannot see any mounting screws or clamps on the current transformer. How do I remove it and mount its replacement?
Thanks.


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## jbfan (Jul 1, 2004)

jdraganescu said:


> Default
> 
> Thanks for your reply. From your reply, it sounds like I can detach the current transformer from the panel box and then have access to the 110 VAC wire connections from outside the panel box. One question: I cannot see any mounting screws or clamps on the current transformer. How do I remove it and mount its replacement?
> Thanks.


Read Neals response. The panel cover has to come off first.


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## joed (Mar 13, 2005)

The transformer is attached to panel through a knock out hole and a lock nut like a piece of conduit.
You have to remove the front panel cover to get it off.


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## FrodoOne (Mar 4, 2016)

jdraganescu said:


> it sounds like I can detach the current transformer from the panel box and then have access to the 110 VAC wire connections from outside the panel box.


Dear *jdraganescu*
Please accept this "comment" as my poor attempt to be _constructiv_e in your learning process, since I note that you, as yet, have few posts on this site.

Please refer to the transformer concerned as the "existing transformer" (and NOT the "current transformer"), because "current transformer" has a specific meaning - which you should (possibly) "look up".

The device which you are seeking to replace is a "voltage transformer" but, because "voltage transformers" are much more common than "current transformers", the word "voltage" is usually omitted in common parlance and _anything_ named just as a (electrical) "transformer" is presumed to be a "voltage transformer".

In your case you require a replacement (voltage) transformer with a secondary output of 16 V AC at (at least) 1 A, in lieu of the existing transformer, which is rated at only 625 mA, because its secondary is is rated at 16 V AC at 10 VA.

(V * A = VA, which equals Watts [W] - in a Resistive load.)


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## zhawkeye (Oct 19, 2019)

If I'm reading the issue correctly, we need to be a little careful here...it sounds as if you want to increase a 16V, 10VA transformer to a 16VA transformer. "VA" is "volt-amps" and is related to wattage by the following:
Wattage = VA x Power Factor
We won't know the power factor in this circuit unless we make a lot of measurements outside the scope of this topic.
If this is truly the question, one thing I don't see is the voltage of the 16VA transformer...unless of course, you already have it...and then I don't need it...
If you're just asking about the wiring, then CodeMatters is correct...polarity doesn't matter. BUT knowing which side is the primary and which is the secondary DOES matter...


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## circuitman (Aug 9, 2013)

on most of these it's pretty straight forward.the wires are the primary(120volt side) ,the screws the low side.it could have a screw or lock nut that holds it in.also some are labeled primary & secondary. but like everyone has said ,you have take the panel cover off.:biggrin2::biggrin2::biggrin2:


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