Your serve hits your own partner
A serve that hits the server, the server's partner, or anything either of them wears or carries is a fault. On a first serve you still have your second.
A fault, not a lost point
If your serve hits your partner, their racket or their clothing, it is a fault, just like a serve into the net. On a first serve you go again; on a second serve it is a double fault and your pair loses the point.
Where your partner can stand
Your partner may stand anywhere on your side of the net, and most wait near the net in front of the other box. Standing in the line of your serve is allowed, but a serve that hits them is your fault.
Off the net, then your partner
The let rule for a serve that clips the net and then hits a player covers any player. So a serve that touches the net and then catches your partner is taken again rather than called a fault.
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Preguntas
Is it a fault if my serve hits my partner?
Yes. A serve that hits the server or the server's partner, or anything either of them is wearing or carrying, is a fault.