Prof X's comment is too funny.
You can buy a decent set of clippers that are made for animals (dogs, cats, whatever) and use them on people. For clippers that are comparible in quality the pet groomers are much cheaper.
Think about it, if the clipper is strong enough to trim an animal like a lab or a retriever, whatever you have on your chest or back really shouldn't bother it at all. I've talked to a couple of pet groomers about this and they agreed that you can use animal clippers on people, but you can't use the best people clippers on animals. They are just not strong enough.
I've had mine a few years and can't remember the brand name, but I'll look it up tonight. I've shaved my head, trimmed sideburns, and did the whole body a few times with no problems at all.