diff --git a/gprMax/materials.py b/gprMax/materials.py
index da515705..0252f920 100644
--- a/gprMax/materials.py
+++ b/gprMax/materials.py
@@ -130,6 +130,7 @@ class Material(object):
             EB = (e0*self.er / G.dt) - 0.5*self.se
 
         if self.ID == 'pec':
+            self.se = float('inf')
             self.CA = 0
             self.CBx = 0
             self.CBy = 0