2005 X Type keeps blowing bulbs, any ideas why this happens and can I install something like an inline fuse so only the fuse blows? Bulbs are now ?15 a pop.

There is short circuit in the wiring of fuse that keeps on blowing.

First remove ALL rear bulbs including licence plate bulbs.Re-install fuse.If it still blows install a signal light flasher in series with a sealed beam headlight instead of a fuse and use a magnetic compass to follow the wiring to the short.The compass needle will move until you reach the short.If the fuse did not blow with the bulbs out,re-install one bulb at a time until the fuse blows,that's the bad bulb or socket.

fuses blow because of dead shorts or excess current draw
to blow a 15 amp fuse indicates a dead short
by disconnecting the rear lights , the problem is in something else you have replaced
could be a problem in the head light wiring

bad bulb will cause it i had one that all the lamps lit ended up being a shorted bulb buy a two back of bulbs i think they are 1557 try changing both fronts first if it still blows put originals back in and try the new ones in the back or isolate it to one side which ever side blows it also could be a short in the switch itself

If it "keeps" lowing the fuse, there can be only one reason for it...you "keep" replacing the fuse without diagnosing the circuits to find out WHY the fuse is blowing in the first place.
When a fuse blows, there is a reason for it. If you do not find the reason and correct it, the fuse will continue to blow.

Please also review this article: Where's The Fuse?

With all of that said, the first thing I would check is all of the light bulbs. Sometimes the bulbs get really hot and melt inside and it causes the metal contacts in the bulbs to touch each other and short the circuit out. This is especially true if you can replace the fuse and everything seems to work ok for a while. They will all work until the offending bulb gets hot and "POOF" there goes the fuse again.

This condition can be hard to diagnose since the short circuit usually goes away as soon as the bulb cools off for a few seconds. In cases like this, what I usually recommend to save time and money is to replace all of the bulbs.

If it is fuse #6 (15 Amp) in the Central Junction Block that keeps blowing, it only powers the tail lamps, licence plate lamps, front park lamps and the front side marker lamps. The cost of replacing all of these bulbs is a LOT cheaper than an hour of diagnostic time at most shops. If this does not fix the problem, then you will have to trace all of the wires going to all of these bulbs to find out which one is shorting and where it is shorting. This could turn out to be very time-consuming and expensive, but at least, you will have eliminated the likelyhood that it is caused by a bulb.

Really need more info but if it blows fuses you have a hot wire touching metal somewhere......
or something plugged in where it shouldnt be.....Or wrong size fuse..You have a brake light switch attached to the brake pedal which is common to fail.....also brake light bulbs and fuse ...check where bulbs are installed at recepticles....check for naked wires touching metal.....also use a good rated fuse...
should be a 15 some are 10 some 20...i would try a 15 if you dont know..................Sometimes your foot can accidently kick wires loose under dash at brake light switch........some cars also have
a cruise control switch above brake light switch.....DONT confuse one with other....NEED MORE INFO ABOUT VEHICLE TYPE TO GIVE CORRECT ANSWER................METALPOET

Make sure its the correct bulbs.Then you have to back probe the circuit to determine where the short is. If its not the correct bulbs issue, then I recommend you test the brake switch on the brake pedal before going any further with this diagnosis.

The fuse keeps blowing out because there is a short circuit. Check the tailight sockets for corosion. Is there a tow package wiring installed?

1 - are you SURE theyre the right bulbs! - if theyre too bright they can blow the fuse, if theyre the wrong type of bulb they will blow the fuse.. best get the bulbs direct from ford, they are always in stock, so are the proper fuses.
2 - theres a center brakelight isnt there? check this bulb too for proper wattage and size/shape
Other than that maybe the wiring in the boot is damaged and shorting?? -----
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You may need to go back and check the bulbs again,,, because if it's using a standard 1157 bulb, the bulb plugs in "only one way",,, but is easy to get installed incorrectly,,, causing a short which blows the fuse.
If you find this not to b the case,,, then remove the emergency flasher switch from the fuse box along with all the light bulbs, front and back. Then reinstall a new fuse.
If it still blows the fuse without bulbs in it, the you either have a faulty bulb seat or a wire is pinched and grounded to the body somewhere. (this will require an intense visual inspection)