In the State of NJ, we have the
Municipal Land Use Law (MLUL) that gives the power to the municipalities power to zone, plan, grant variances, subdivide, etc. If you want to understand how it works in NJ, I suggest that you read it.
A variance is not at the whim of the board of adjustment or the planning board. It is controlled strictly by law to ensure that zoning and master plans are followed. We basically have two types of variances; a c (1) which is for
hardship when a lot doesn't meet the zoning standards and a c (2) for
special circumstances when the variance will further the intent of the zoning and benefit the community. That is stating it very simplistically. Here is one
case that will shed some light on it if you care to read it.
So when I look at what OP has posted I see nothing of a
hardship or a
special circumstance that would warrant the granting of a variance.
OP has a lot that conforms in dimension to the zoning. The building of a pole barn (that would normally be an accessory structure to a dwelling in this zone) on a vacant lot without the lot being developed as a residential lot is not something that is a
hardship or a
special circumstance under the MLUL. But that doesn't mean that board of adjustment will necessarily deny the variance. But it does mean that the granting of the variance can be challenged and rendered void if someone in the neighborhood does challenges it. I think that it would be contrary to the intent of the zoning not to have the property developed as a residential lot if kept separate.
There is no hardship, so I'm guessing that it would have to be a c(2) variance. I would love to read the memorializing resolution that grants this variance (if it is granted). He would need 5 out of 7 member to vote for it. The Board's attorney will verse the members on the law before the vote. And since this municipality is the Pine Lands, I'm sure the follow the law to the letter.
Time will tell and I hope OP comes back and tells us what the outcome is.
My money is on merger of the lots as a condition of the issuance of a building permit for the barn and the variance denied.