I have posted this before :
Try this for some guidance :
https://www.electricaltechnology.org/2013/11/how-to-connect-portable-generator-to-home-supply.html
Wow a lot of have not tried and telling every man as his dog how it can't be done, whilst here on planet earth the rest of us just do...
I would advise to use the main consumer unit....plug and socket without out a good earth and rcd is asking for trouble...its always hammering with rain and its all ways just at that time when you don't need it and are fugged off and then oooh that tingles a bit and whats that burning pork smell.
1. You will need to Isolate the house from the mains so you don't power the grid...if you have an mains isolator fitted great if not get you power company to fit one, use a commando socket to bring in the power...they are designed to not let you get toasted if you need to unplug the power quickly. Use a generator switch to change between gen and mains supply for the main consumer unit. about £45.
2. Work out the type of earth you have... you can use TT or TNS to take and earth to the gen...tt is a earth rod banged in the ground TNS is where the earth is taken from the shield of the mains cable as it enters the house. Personally i would not use a pet /neutral earth.
3. An earth via the three pin plug does not ground the generator only the earthing point on a generator does as its attached to one of the windings. You need to run an earth directly to that earthing lug. Use the best earth you can..the house earth.. just run an earth cable direct from the house to the gen.
BS7430
7.1.3 Unearthed generators (rating below 10kW) supplying a fixed installation
Where an unearthed generator is to supply a fixed installation it is recommended that ADS is adopted as follows:
a) One pole of a single phase generator should be connected to the installation MET- ie the generator earthing point to the main earth terminal in the house.
b) The MET should be connected to an earth electrode - so an earth rod (TT) at the house or via TNS. If I had a pen earth system whereby the the earth came in via the neutral I would be adding an earth rod.
c) The installation should conform to BS7671 with all exposed conductive parts and all extraneous conductive parts connected to MET
d) The installation should be protected by RCD's - main consumer unit
The earth electrode should have a resistance to earth not exceeding 200Ω
The RCD will not provide protection for faults on the generator side of the RCD, and consequently precautions should be taken. - ie the bit from the gen to the main consumer unit with rcd or if you are using a extension lead ( hmmm thats a no from me) its all risks no rcd... ie do not trust a genny that says it has an RCD...it probably does not and if it does will if trip quickly enough.... But a small suitcase one has few exposed metal pieces and some simple precautions - ie don't turn it off or on in bare feet in a thunderstorm...its how much you value your life.
Basically..isolate the mains, provide the best earth you can, use the main consumer unit if you can via gen switch or if you cannot use a sub consumer unit with rcd, fuses ( mcbs/rcbo etc etc) running you extension lead from that and a good earth. Earth the generator chassis directly not via the plug outlet.
On a small 1100w we run our heating , 4 computers, a internet router TV and a couple of lights. Make sure that you buy a stabilized generator that produces a sine wave output and put the load on slowly. Do not listen to all the naysayers about sine wave...our little clark unit does not vary by 0.01% in is frequency output, the grid legally can vary by 0.1%