Not to pile on, but I'd say that this is not just underexposed, it's underexposed by quite a bit. Assuming that your electrical plate is similar color to the ones I'm used to seeing, you're at least a stop underexposed even here - and the display shows that you've already boosted exposure by two thirds of a stop. If you're boosting exposure by what appears to be two stops, you're going to get some noise.
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!