Dictionary Structure
If you have a collection of Meters and you want to be able to find the ONE based on a property, this is how I would do it:

Create a List of Meters, say l..

List&lt;Meter&gt; l = new List&lt;Meter&gt;();


Then implement Extension methods like so..

public static class MeterExt
{
    public static Meter GetByErm(this List&lt;Meter&gt; l, String sErm)
    {
        Meter r = l.Find(s =&gt; s.ertNumber == sErm);

        return r;
    }

    public static Meter Get(this List&lt;Meter&gt; l, String sMeter)
    {
        Meter r = l.Find(s =&gt; s.meterNumber == sMeter);

        return r;
    }
}


Then you can find your meter like so..

Meter m = l.Get("fsadfa");