There is nothing wrong with 8 (or even 10 sockets as I have on an extension lead under my desk) IF the thing is properly fused.
It might not even be a motor fault, you might be in a situation where there is no effective earth provision, nor adequate cable protection, nor adequate protection from electric shock.
Wiring to outbuildings is never just a case of extending the cabling. Without a proper understanding of the existing installation, from the incoming cable to the consumer unit, to the type of earthing in the main property then you cannot even start to know how to effectively and safely wire and earth the outbuilding.
There is some guidance here (to the 16th edition of the wiring regs, but we are almost to the point of using the 18th edition) It is not extensive nor does it cover all situations.
https://electrical.theiet.org/wiring-matters/16/elect-inst-outdoors.cfm?type=pdf
I've seen a similar 'shock' problem in a kitchen of a relative many years ago, the cooker earth had fractured in the consumer unit due to bad stripping of the sheath, one change of ownership later and a couple of years later the cooker oven element had failed (the issue I was called to) but the element had burst and shorted to 'earth' but as an effective earth was not present the entire cooker was raised to live potential, the fuse also having not failed due to zero fault current. The floor was wood, quite dry and thus reasonably insulated, but a potentially fatal shock was less than one outstretched arm away with a very well earthed metal sink. Rather than just fix the cooker and the failed earth, a full wiring test was performed followed up with the installation of a new consumer unit with an RCD.