Also, other factors include, jobs, local economy, interest rates, inventory, housing shortage, etc. 

The other factor is that actually, there is potentially nothing wrong with the existing wiring in terms of use or safety, but once someone starts to futz with it, it can become wrong and unsafe very easily, which is why many electricians advise to leave that **** alone.The second thing I feel compelled to say is I am not sure how you plan to use a plastic box and still maintain the ground.

Just make sure you factor in management and repairs.

Estimate around $1000 per month for insurance. 5% vacancy factor is each tenant will stay 20 months.

Factor in $800-$1000 per unit per year in maintenance and repairs and set aside another $1k per year in reserves. 

It depends on a few factors such as age, income expectations over your career, etc. 

The one big factor for me was looking at the principle that would be paid down over the next 5 years if I didn’t refi and if I did.

@Steven Winfield a 3% vacancy factor is each tenant staying for 33 1/3 months.

The property is for capital growth, but it seems that the cash-flow properties in the US are many factors more lucrative than down under.

If you factor other expenses you’re at around $200 more you're looking at a pretty manageable temporary debt.