power invertors

i have recently fitted a 1500w 240v power invertor into my 2003 ford transit van i'm running a dual battery setup and which is split by a split charge relay. the invertor is connected to the secondary battery but when ever a device such as a hoover (1100w) is run off it the invertor ammeter readout goes from reading 150 amps to 0 amps(the max limit on the ammeter read out is 200 amps) which then in turn trips the 200 amp circuit breaker switching the whole lot off (highly annoying!). also when using a laptop charger the invertor goes into protection mode, which i then have to switch off and on before it will work again i have wired the the invertor using 4 gauge cable +ve to the +ve side of the battery -ve to the -ve side of the battery(the cable's connecting the invertor to the battery are 24" long) and ground to the chassis. have i wired this correctly or have i just suceeded in blowing up a very expensive invertor.