my brother has asked me to whelp down his bitch. she had a 1st litter last year and was a good mum my sister whelped her down last time. Are the bars in the box a good idea, are they there so she doesnt sit on the pups? my sister didnt use them and had no problems

Get a book called:
The Book of the Bitch
as this should answer most of your questions although I don't think it covers the really important one that your post raises and that you didn't actually ask :-(

My main concern would be expecting a bitch to whelp in a place that is not her home.
as reccomended the book of the bitch is very good,but whelping any bitch of any breed is a huge responsibility one usually taken on by the breeder not a family member :)

I would agree entirely.  And would add an "experienced" breeder so that the poor bitch isn't at risk.:(
I find that pig rails aren't necessary if the bitch and litter are never left unattended.

This is first time round for both of us here so I've constructed a whelping bed with rails and will just take them out if I find they aren't needed.  It's easy done.

I haven't put them in so I can leave puppies and mum unattended but because lots of the books recommend them and because I have no experience would rather be safe than sorry, and, as I said, they are removable if they are not needed or become awkward.

I only use them for the first few days.
:)

My whelping boxes have them, and I take them out when the pups start moving around.  They give me some peace of mind that if mum gets snuggled down with babes feeding none of the little ones can get stuck behind.  Even whne you are watching them all the time, there are the odd few minutes (eg going to the loo) when you are not with them, and it only takes a very little while to lose 1.
bye
Gwen