  The properties of 5D gravitational flux tubes are considered. With the cross section and 5th dimension in the Planck region such tubes can be considered as string-like objects, namely $\Delta-$strings. A model of attachment of $\Delta-$string to a spacetime is offered. It is shown that the attachment point is a model of an electric charge for an observer living in the spacetime. Magnetic charges are forbidden in this model. 
Some properties of a $\Delta-$string