npm install bower fails

I am trying to install bower on mac os Yosemite with npm but it fails with the following message

npm ERR! fetch failed http://registry.npmjs.org/nopt/-/nopt-3.0.3.tgz
npm WARN retry will retry, error on last attempt: Error: connect ETIMEDOUT
npm ERR! fetch failed http://registry.npmjs.org/request/-/request-2.53.0.tgz
npm WARN retry will retry, error on last attempt: Error: connect ETIMEDOUT
npm ERR! fetch failed http://registry.npmjs.org/shell-quote/-/shell-quote-1.4.3.tgz
npm WARN retry will retry, error on last attempt: Error: connect ETIMEDOUT
npm ERR! Darwin 14.4.0
npm ERR! argv "node" "/usr/local/bin/npm" "install" "-g" "bower"
npm ERR! node v0.12.7
npm ERR! npm  v2.12.1
npm ERR! code ETIMEDOUT
npm ERR! errno ETIMEDOUT
npm ERR! syscall connect

npm ERR! network connect ETIMEDOUT
npm ERR! network This is most likely not a problem with npm itself
npm ERR! network and is related to network connectivity.
npm ERR! network In most cases you are behind a proxy or have bad network settings.
npm ERR! network
npm ERR! network If you are behind a proxy, please make sure that the
npm ERR! network 'proxy' config is set properly.  See: 'npm help config'

npm ERR! Please include the following file with any support request:
npm ERR!     /Users/larris/npm-debug.log

i have installed successfully other packages with npm

   /usr/local/lib
├── cordova@5.1.1
├── gulp@3.9.0
├── ionic@1.6.1
├── npm@2.12.1
└── yo@1.4.7

but when i try to install bower i get the above error. I am not behind any firewall and my npm config is

; cli configs
user-agent = "npm/2.12.1 node/v0.12.7 darwin x64"

; userconfig /Users/larris/.npmrc
registry = "http://registry.npmjs.org/"
strict-ssl = false

; builtin config undefined
prefix = "/usr/local"

; node bin location = /usr/local/bin/node
; cwd = /Users/larris
; HOME = /Users/larris
; 'npm config ls -l' to show all defaults.