Help Making HTML Drop Down List Go Into Javascript Code

I have some code to pick a wire size and conduit size from 2 separate drop down list. Then inside the js it is evaluated to decide how many wires. My problem is I can't figure out how to make the drop down options go into the JS. I just put in an error alert to test if they were for now.

Here is my code:

function fillcap(){
var wire = document.getElementById("wireSize");
var conduit = document.getElementById("conduitSize");
if (wire.option.length >= 10 && conduit.option.length == .5) {
windows.alert("Wire Size exceeds conduit max fill!")
}

And the html

<h2>Fill Capacity</h2><br>
<b>Wire Size</b><br>
<select id ="wireSize">
<option value="1">#14</option>
<option value="2">#12</option>
<option value="3">#10</option>
<option value="4">#8</option>
<option value="5">#6</option>
<option value="6">#4</option>
<option value="7">#3</option>
<option value="8">#2</option>
<option value="9">#1</option>
<option value="10">1/0</option>
<option value="20">2/0</option>
<option value="30">3/0</option>
<option value="40">4/0</option>
<option value="250">250</option>
<option value="300">300</option>
<option value="350">350</option>
<option value="400">400</option>
<option value="500">500</option>
<option value="600">600</option>
<option value="700">700</option>
<option value="750">750</option>
</select> <br>
<b>Conduit Size</b><br>
<select id="conduitSize">
<option value=".5">1/2</option>
<option value=".75">3/4</option>
<option value="1">1</option>
<option value="1.25">1-1/4</option>
<option value="1.5">1-1/2</option>
<option value="2">2</option>
<option value="2.5">2-1/2</option>
<option value="3">3</option>
<option value="3.5">3-1/2</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
</select><br>
<input value="Wires allowed" onclick="fillcap()" type="button">
<input type="text" name="myresultbox" id="resultbox10"> Wires<br>

Thank you for any advice.