We are all speculating a bit because you have not provided enough details for us to have the same frame of vision as you do, and since there are no pictures it makes that hard with out the details.
You do not say where on Planet earth you are - so knowing what Voltage and the power system in your neck of the woods may be different. Here I assume you live in the USA and have a standard 120V/240V service.
To make sure we are on the same page as you and understand your situation...
'very hot connection ... after wire brushing a rusty conduit clamp connector located at my water meter'
We assume the very hot connection you are referring to is the rusty conduit clamp you wire brushed.
This indicates you fixed a bad connection and now you see a separate more serious issue - the connection is hot.
You did not cause that issue by cleaning the clamp connection, you just revealed the issue - like fixing dry wall and finding out there are termites in it. Changing the clamp will not resolve your issue (although it is not a bad thing when you fix the real issue.
A connection to your water meter, you state conduit clamp so lets clarify here what you have..
- Is your water meter electronic or is it mechanical ?
- Is your water meter a Mechanical type and the conduit clamp is connected to a water pipe ?
- Is your water meter an electronic type and the conduit clamp is connected to an electrical Conduit Pipe ?
- Please tell us where that wire on the clamp goes to, where is the other end of the wire connected ? We are assuming it is a ground wire .. but have no idea with what you have provided. Does it go to your panel or a grounding rod ??
- When was the home built ?
- Was the Electrical ever upgraded or are there sub panels in the house or outside like for a garage ?
The problem you have is that current is flowing through that (assuming it is a ground wire) ground wire! Which is Incorrect, changing the clamp will not fix the real issue electrically something is not correct.
This means that power is not flowing from Neutral Line to the Load.
It can also mean that the line you have connected to that clamp is really your neutral ..
As one commenter said you should go through turning breakers off and verifying if it is one circuit or any circuit that causes this issue. Turn off all of them and then only your washer , if it gets hot maybe it is not wired correctly, turn it off and try a completely different one, not your basement lights..a different one than washer and basement lights and see if it occurs, if it does - I would venture it will for all circuits but can't be 100% sure without testing all of them.
Given you have plugged in to two different circuits (washer, basement lights) and see this same condition I am leaning towards your panel not being wired correctly. Depends on where that other end of the wire goes to ..
If all or any circuit causes this, check your Power - Line-In to the panel, You probably have 4 Wires , L1, L2, Neutral and Ground. Check the panel bonding, make sure none of your neutrals is tied to the grounding or vice versa grounding to the Neutral.
Be very careful inside the electrical panel, if you are not you can get Electrocuted as opposed to shocked. IE 6 feet under as opposed to a new hair do..
PS: Older homes may have some sneaky things done to pass a quick inspection, if it was a rental at anytime (for example neutrals used as grounds in an outlet) - look for this.