Hello
Hopefully someone can help me?
Just wondering if its normal for acrylic nails to split?
It has split vertically down the nails on 3 nails and they have been on 2 weeks? they have been looked after properly and done no 'hard work'

Your profile doesn't say what training you've had, and your post doesn't say if they're you are the client or the Tech, but vertical splits are almost always the result of pressure from the sides. The only other cause is getting Scrubfresh (or equivalent) on the blended tip but that would be obvious before the L+P was applied.

A bit more info would be helpful!!

Hth's

Im not the client or the Tech.
Its my Granmdas nails, she totally loves them, well did untill they split.
She is not one that will put her nails in her mouth ever!
She has soaked them off today and has rebooked somewhere else. I just wondered if there could be some obvious reason for it happening that i am missing.

There is an obvious reason .. pressure. Pressure on each side of the nail, as vetty expalined, is the only thing that causes nails to crack vertically on the nail plate .. they have been squeezed somehow.

It may be that the technician did not build the nails as strong as she might have done, but even so, the only thing that would crack them in that manner is pressure from the sides ... most often the case is the client squeezing them with her teeth. If it's not the teeth it is something else she has done to them .. nails don't just crack down the middle without pressure.