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Another main lug question

9 years ago

Hi all,
I have read through a number of posts that deal with wiring main lugs and sub panels, etc., but don't feel like any of these help out in my situation.

My wife and I have bought a house with aluminum wiring (pig tailed however), and I have decided to rewire it w/ copper. While I'm at it, I have decided to change the existing breaker panel as it's out of space and quite old.

The setup in the house is that there is a main breaker (a single breaker on the outside and 2x 100A fuses on the inside) that feeds the main lug (my main panel). I'll refer to them as the 'main breaker' and 'main lug' from now on in this post.

My understanding is that when wiring a sub-panel, which technically my main lug is; one needs to have 4 wires (2 hot, a neutral and a ground). Looking at the existing connectivity, I only see two hot, and a neutral connected to the neutral bar in the main lug. Now keep in mind that there are wires everywhere in the main lug so I might be missing something here.

My first question is:
1. Is it possible to have only three wires connecting main lug and main breaker, and still have everything come up clear when checking plugs for correct wiring with the receptacle tester?

My other question deals with the main panel I bought in order to replace my main lug. I purchased a Siemens XP32100 (only picture I could find is located here: This panel seems to be specific to Canada as I haven't seen it on any of the US sites.

In order to prep the panel to act like a sub panel that it is, I have disconnected the bar at the bottom (it connects ground bar and the neutral bar). This has resulted in the following:
1. The long bar on the left is not moving as it is still connected to the case via screwed copper strip
2. The long bar on the right is moving up and down as it sits on something that looks like a plastic channel. I will contact Siemens to find out how to stop it from moving tomorrow.

I have two questions here:
1. I am assuming that two small bars that can be seen in the picture can be used as grounding bars
2. Am I supposed to remove the screw connecting the long bar on the left from the case even if I intend to use it as a grounding bar?

Your help on the above matters is greatly appreciated.

Thank you,


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