my steam iron keeps tripping the consumer unit why and how can i stop it?

You have a serious electrical fault in your iron - have it repaired (probably not worth the expense and may take several weeks) - change it under warranty if possible - buy a new one.

The breaker in your consumer unit is designed to disconnect power if it detects an unsafe condition - it may be over-current but is more likely to be a short between power and earth.

Peccavi
November 2008