Safe Power Question . . .

You are way below the power rating of a typical 15 amp power strip.

You can plug as much as you want into the power strips as long as you do not overload it. Most power strips are circuit breaker protected, so if you do not trip the breaker, you are OK. A label on the power strip should denote the maximum amperage rating of the unit.

Larry

I tend to agree with the other posts here.  A standard 15 AMP household circuit delivers about 1800 Watts of power, or more than 6 fully loaded ZW's.  while there are losses due to heat and such I wouldn't worry with even 4 ZW's. ( just realized you said Z4k, not ZW...  so revise to 4 fully loaded Z4K's or 3 and some other smaller stuff safely)  On the other hand, I would suggest purchasing a high quality power strip that is UL rated or at the very least Clearly states it's maximum current on the packaging.  Many of the low cost plastic power strips have un-reliable circuit breakers and in a thread a while back several people mentioned them as fire hazards.  Also keep in mind anything else that runs on the circuit including any other wall outlets and room lights.  Half a dozen 75 Watt light bulbs will put a big dent in your available power.  If at all possible try to run nothing but your transformers on the circuit.  

Here's the old thread that went into a lot on power strips, among other things:  https://ogrforum.com/t...ips-for-transformers