Is an advance payment to an electrician lawful?

Working hours must be listed separately without fail.
(Here is a court ruling
Local Court Mülheim dated 30.7.2015, 12 C 1124/14).

You can also demand that he itemizes the services performed individually on the interim invoice.
How are you supposed to know what the 1500 euros were used for?
It is not at all comprehensible which services have already been rendered, what is being paid for here, and how one arrives at such a round gross amount. That already makes one doubt.

Working hours must be listed separately.

It is a partial invoice. Not the final invoice.

It is a mandatory indication regardless of the type of craft invoice presented.

See § 14 para. 4 UStG.


Off-Topic:
These are also needed for tax reduction in the tax declaration in the case of a renovation for craft invoices. The hours of all partial invoices are entered there.
If these are missing on an installment invoice, they could not be claimed.

In our partial invoices from the electrician, no detailed lists were made, only the main points were briefly listed. However, since the work was always properly carried out at the times, we always paid promptly on the same day.

Off-topic: If I didn't give the deserved money to everyone who seems unpleasant and arrogant to me, I could save a bunch of money every month.

Sounds familiar to me... If you have agreed on progress payments, then that’s okay. If not (as was the case with us back then), I find that just as inappropriate as the original poster. At that time, I refused to pay an almost identically worded progress invoice. For what, please? The "services rendered so far" can of course be itemized! I stood my ground and coordinated this with the general contractor. The electrician did not comply with my request to itemize the invoice items back then and only received his money with the final invoice. From my point of view, it would have been easy for him back then to list the work already performed from his offer for our requested additional work. But since the progress invoice was far higher than what I could ascertain as completed items, I risked the dispute. However, he still completed the work carefully and as ordered. However, partly absurd cable lengths were installed and charged for lines going outside (TV, doorbell, electricity). That was maybe his little revenge... At that point I didn’t want to argue anymore and paid it.

so in retrospect I ask myself whether my actions at the time caused more trouble than necessary. Back then, however, I was really pissed off because of the [Abschlagsrechnung], the amount of which was not understandable to me. A payment term of 2 weeks is okay from my point of view.