Noises on Phone line when touching appliances

[Homer Simpson]

Not so much an engineering question, but electrical.

I've got a noisy phone line in my kitchen and not sure what's going on... more curious about the electrical theory than anything else.


-when operating either of 2 light dimmers in the area, loud hum on phone line.
-when first touching any grounded appliance, hear a click on the line as if I am discharging or something.
-the phone is plastic all around so it seems bizarre to me that it would make any noise when touching appliances.

Any thoughts?
Thanks.

 

[Phrak]

Light dimmers are notoriously noisy. 120 times a second there's a sharp turn-on edge, that splatters electromagnetic waves over the spectrum. Turned all the way on, you should notice that the noise diminishes.

When you touch ground a high current spike occurs that takes your body to ground potential. The abrupt change in current (from zero, before discharge) is what causes the broadcasting. There are a lot of frequencies represented, so a good chance of picking it up in a circuit not shielded or filtered well enough. Apparently, it doesn't require a noticable arc to receive it, in your phone.

People are modeled at about 50 pF capacitance. There's also self inductance, even a straight conductor. The current actually oscillates a bit before going to zero, if the resistance isn't too high. This part of the signal has a narrower band, than the sharp, arc-over start.

 

[oswaler]

As a scientist, it is important to consider all possible factors and variables when trying to understand a phenomenon like noises on a phone line. In this case, it is likely that the issue is related to electrical interference.

When you operate a light dimmer, it can create electrical noise or "dirty electricity" which can travel through the wiring in your home and interfere with other electronic devices, such as your phone line. This can explain why you hear a loud hum on the phone line when using the dimmers.

Additionally, when you touch a grounded appliance, you may be creating a small electrical discharge which can also interfere with the phone line. This is because electrical currents can travel through your body and into the phone line, causing a click or noise.

It is also important to consider the quality and condition of your phone line. Old or damaged wiring can also contribute to noise on the line.

In terms of the plastic phone, it is possible that the noise is not coming from the phone itself, but rather from the interference caused by the electrical currents traveling through the wiring in your home.

In summary, it is likely that the noises on your phone line are a result of electrical interference from other devices or wiring in your home. It may be helpful to consult an electrician to ensure that your wiring is in good condition and to mitigate any potential sources of interference.