earth bondind

very conservatively ?

Give us a hint of what you trying to do? Or should we just use WAG's

Please say which country when asking questions (presuming UK).

Any exposed metalic structural parts of the conservatory must be bonded back to your main earthing terminal. In a home with a standard electricity supply, the cable used is normally 10mm² green/yellow sheathed, although there are special circumstances which would require the use of a larger crosssectional area conductor.

What causes you to ask this question? Do you know what earthing system your house currently has? See