Not to worry - your comments are most helpful and I'm not at all opposed to judgements :)

I suppose I'm trying to do a Monte Carlo where the outcome (mV) is dependent on the probability of success. If, for example, 8 units (in my case presynaptic terminals) release chemical transmitter each with a constant probability (0.22) and the individual (read single unit) response to released transmitter is 0.51 mV with added error (0.31 mV), what is the expected mV response over 100 trials given 8 probabilistically active units (assuming linear summation of voltage).

You are right in that my simple solution resulted in negative voltages. Negative voltages are permissible so long as they do not exceed the absolute value of my error term (which they most certainly do in my failed attempts).

Hope that helps clarifies my objective. Thanks again :)

Thank you, Jim.

Apologies for the ambiguous language. I have a measured probability (0.22) of success. The success of each trail corresponds to a particular weight (e.g., measured voltage 0.51 mV). This measurement has error (coefficient of variation + channel noise = 0.31). I am trying to calculate how 8 such units with similar successes and weights would behave (i.e, what is the expected mV and variance).

Here's what I did....
I have treated weight as a random normal variable such that:

weight_SD = RandomVariate[NormalDistribution[0.51,0.31], 100];

pTrials = RandomVariate[BinomialDistribution[8, 0.22], 100];

data = pTrials * weight_SD

Does this seem sound? Thanks again for the help :)