Equi=Core Hum & Other Issues

There are 3 lines from the pole that run parallel to all the rowhomes; 2 heavy gauge, one thin cable. They are mounted to the rear wall and extend about 15" outward and 12" below the square weatherhead.

Wow.

Well, it sounds like the utility power lines are below the " square weatherhead". That’s good.....

The service drop consists of two black cables and one white. The drop is U-shaped but the black cables enter the side of the weatherhead and terminate inside. They are horizontal at the point of entry.

"The drop is U-shaped but the black cables enter the side of the weatherhead and terminate inside."

weatherhead? Sounds more like a junction box. How big is the box? Just a guesstimate.

The drop is U-shaped but the black cables enter the side of the weatherhead and terminate inside. They are horizontal at the point of entry.

I have no idea what you have.... No Idea.... Has to be really old though.
What stops the rain from blowing in through the side of the box where power wires enter?
I assume the box is surface mounted? Is there a conduit that drops out of the bottom of the box?

The white cable hookup looks like your diagram and enters the bottom of the box.

240V Lines enter through the side of the box, and the white neutral wire enters from the bottom of the box. Correct?
Is the box made of steel?
.

@jea48 

I have no idea what you have.... No Idea.... Has to be really old though.
What stops the rain from blowing in through the side of the box where power wires enter?
I assume the box is surface mounted? Is there a conduit that drops out of the bottom of the box?

It is very old. This is an old neighborhood which used to have blackouts during storms. We finally got new transformers on the poles. Power is stable and higher now, 122-124VAC.

Nothing stops the rain from entering the box. The black cables from the drop make a 90° turn and enter through 2 holes on the exposed side. The white neutral enters through the bottom and keeps a perfect U- shape.
What's interesting is the electrician knew exactly where the water leak was. I was looking at the meter and he said no, it comes from up there.
I'm going to take pics. I'll try and post them for you over the weekend.

The box is surface mounted and looks like steel, about 6" x 4". The conduit drops out of the bottom and is very weathered looking; really beat up. 

I'm going to check out the hookups on some other homes.
Jim, I always appreciate your help.
Jim S.

@jea48 
These are pics of my service drop connection to my mains.

https://ibb.co/qpQnYf5 https://ibb.co/VVzq1W5 https://ibb.co/JCsg9jj https://ibb.co/Y3ynkkq

All the other rowhomes have this type of connection. 

@lowrider57

Pictures are worth a thousand words......

Especially this one.....
https://ibb.co/qpQnYf5

Your service entrance drop is a cable. It is not a conduit with wire installed in it as I imagined.

It appears to me rain water is entering between the outer sheath of the service cable and the weather proof strain relief connector on the top of the meter socket. My guess is the rubber bushing, (or possibly, depending on the age of the connector, Oakum Packing Material), that is supposed to seal the service cable and the metal connector from allowing water from entering the meter socket is shot, deteriorated, allowing water to enter.

A band aid that may stop/help from rain water from entering the connector, therein the top of the surface mounted meter socket is to apply a good quality pure silicone caulking around the service cable and the weather proof strain relief connector.

Clean the cable with a dampened dish soap and water washcloth at least a couple of inches above the top of the connector and the entire top of the screw down cap/nut of the connector. Remove any loose debris that may be laying between the cable and the inside of the connector. Rinse off the soap with a slightly water dampened clean washcloth. Repeat as necessary to remove all dirt and soap. Repeat process if needed to get all surfaces clean. Allow to completely dry several hours. Surface areas must be 100% dry.

Apply the pure silicone caulk around the cable where it enters the connector throat, opening. Make sure you force, inject, as much silicone into the top of the connector between the cable and the connector as possible.

Finish off forming the silicone product using your finger. You want the silicone caulk to cover the top nut of the connector so the water will shed down the side of the connector.

Next using your finger slightly form, taper, the silicone caulk up all around the cable. Do not leave any globed pockets for water to puddle. You want the finish product to look like cone.

(To stop the silicone from sticking to your finger, as you form it, slightly moisten the tip of your finger with water as you form the silicon.)

Jim.