R.I. Gen. Laws § 28-27-19: License displayed in place of business.

In every place in this state within and from which a pipefitter or refrigeration/air conditioning or fire protection sprinkler systems or air distribution business is conducted as specified for a pipefitter or refrigeration/air conditioning or fire protection sprinkler contractor/sprinkler fitter master or sheet metal contractor there shall be at all times a certificate of license as provided in this chapter. The certificate shall contain the name, address, social security number, state license number, classification, and limitations, if any, on the license. All vehicles used in those businesses shall be identified as being regulated by the bureau and will display with no less than three-inch (3) lettering, the contractors category, license number, and company name.