How many holes?

[Durhamdan]

I plan to drill 3 x 20 mm holes (lined with plastic conduit) through the external wall of my house to run cable for: outside wall light, socket, low voltage garden lighting.

How should I position these new holes to minimise structural weakening of the wall? Should they be arranged vertically, as shown? Should they be located under the window? Does it matter where they go?

The wall already has holes for the boiler vent and wastewater drain pipe, as shown in the diagram.

Or, as the holes are quite small (20 mm), is this something I don't need to worry about?

Cheers for any advice.

 

[Bodgeit and scarper ltd]

 

[Nige F]

do them on the horizontal courses of mortar.......at the corner of a brick (ie a "perp") joint.....that`ll minimise mess from brick spalling.......do small dia. hole thru from outside then ream with 20mm from inside

 

[noseall]

nothing to worry about.