Depends where you are. Where I live it's no modification. If it's hard-wired the tenant can't touch it.
Though in reality many landlords don't mind as long as you know what you're doing and return it to how it was. Just a problem if you get a jerk landlord.
Here a landlord can do an inspection with 48 hours notice. If you're out of town they are allowed access without you present. Also the landlord can end your tenancy with 90 days notice with no reason.
Penalties would depend on the adjudicator's opinion of the damages and risk.
Though in reality many landlords don't mind as long as you know what you're doing and return it to how it was. Just a problem if you get a jerk landlord.