That hole is pretty small, what could go wrong?

It's such a small hole, why should you bother to seal it? It doesn't look like much could get through. I can ignore it, can't I?

It's hard to see from this far away but there is a small hole where the conduit attaches to the house.

Look closer and you can begin to see the unsealed opening.

Close up of the unsealed hole. I wonder what is on the other side of this wall?

This hole is hard to see from far away but on closer inspection of the electrical conduit an unsealed siding penetration is easy to notice. The hole is less than an inch wide but this is a lot of room if you are an insect, a drop of water or even a small rodent. From the outside it can be difficult to tell where the hole leads. In this case, with the hole next to the main electrical service meter, you really need to investigate farther.

The other side of the unsealed hole. It leads right in to the back of the main electrical panel.

Electrical panel with evidence of prolonged visiting by (hopefully) friendly neighborhood spiders and insects.

As you can see from the picture above, the hole leads directly to the main electrical service panel for the house. When the panel was opened and the safety cover removed it was quite evident that this panel was found to be an inviting and cosy home for spiders and other insects. 

This is a problem. There is a lot of organic and potentially flammable material in the electrical panel. This can trap heat and serve as a source of ignition for a fire. The panel needs to be cleaned by a qualified party and the hole in the siding needs to be repaired. A little bit of maintenance and routine repair can prevent a much bigger problem down the road.