Delete on warehouse table timed out

Hi, 

i'm building a little warehouse and created some staging tables. Before loading data into these tables, i want to delete the table data.

1. Delete from [testtable]

2. Insert into [testtable] select * from [basetable]

The statements are executes via script activity in a data pipeline

In most cases the statements ran in timeout error "Operation on target delete destination table failed: Execution Timeout Expired. The timeout period elapsed prior to completion of the operation or the server is not responding."

A select on DMV sys.dm_exec_requests shows wait type "EDC_EXEC" (?) , also after getting the timeout error...