Though not an electrician, I can offer the following as it relates to your pending home sale-
1. 100A is the newer code minimum, but yes there are plenty around that still work and run OK on 60A.
2. If you're home buyer is getting an FHA mortgage, the home inspection and appraisal will be more stringent in general (slightly). Just a warning.
3. Do you have fuse boxes or circuit breakers? Fuse boxes may be a problem. Also, old wiring (call it knob and tube wiring) is generally seen as a problem. Many banks, and buyers, will back off.
That's what I can offer you on that. Good luck,
What needed to be addressed was not the existence of fuses, but extensive knob & tube wiring. Insurance companies tend to be more concerned with this than fuses. To upgrade would require a new power drop, circuit panels and plenty of replacement wiring. If your home lacks the convenience of numerous outlets (1 every 6 - 10 feet), additional new circuits would be well worth adding.
As for what the minimum amperage requirement is, really depends. You could over kill each unit with 200 amp service which makes no sense unless you were running electric heat, electric hot water, electric dyers, AC... you name it. However the short answer would be 100Amps per unit with a 200Amp service.
Oh, and by the way,good luck with your sale.
In the multi-unit business ourselves. I find it depends on the local inspector, who seem to all want an upgrade with good reason however, that is not always feasible. The other factor is what each unit is offering. Obviously your rental rates are determined by the tenant and so the MORE you can offer the higher the price per month.
EXAMPLE: We have a building with 3 units, each unit offers 100Amp service and our tenants enjoy electric hot water tanks, dishwashers, washer and electric dryer in their own units, window AC's, electric stoves and refrigerators, computers, telephones and all the other tv equipment . Rarely do we have a problem with breakers flipping.
On a side note: Not that this has happened to us...but if you listen, when there is a fire it seems the fire inspector and your insurance company automatically asks about the electric and for any permits pulled.
And then on anoher side note: My husband grew up with fuses and he likes fuses. But that's another conversation.
Do feel free ton contact us if you have any other multi-unit questions-KarissaMoore