30 Gal Electric HLT Design

Eventually I'm going to want to go bigger so I would rather do things right the first time. I'm looking to design a 30 gallon electric HLT and I need it to do what's listed below but I also need it to work for 5 gallon batches.

1. Heat 30gal to 175 deg within 90 minutes
2. Maintain the temp within a degree or two
3. Able to turn on from a timer
4. be insulated

This weekend or early next week I would like to get the 220 plug and breaker wired in. What prong style should I be using with a setup like this?

Does anyone know what size element I need? Do I need 2 for 30 gallons?

Thanks!

If it's a plastic tun, you could always check my thread. https://www.homebrewtalk.com/f51/i-decided-start-building-brewing-system-106668/

I used heating elements from water boilers. I have 3 of them, but I have only used 2 so far. As the HLT is insulated, it's quite effective. Not tried it with 30 Gallons yet, but I am pretty sure you could get it up to 175 within an hour.

I have a 30 gallon all electric HERMS system. I have two 4500 watt elements in both my BK and HLT. I don't run both the BK and HLT at the same time. 9000 watts pretty much maxes out a 50 amp GFI breaker. It takes me 1.5 to 2 hours to bring 50 gallons of water from 55F to 165F, depending on the ambient temp in my garage. I batch sparge and begin heating the wort soon as I collect the first runnings. After the second runnings are collected, wort is usually brought to a boil withing 30 min, again, depending on ambient temp. After the wort (39 gallons) is boiling, I run the elements on 85% power to maintain the boil.
I think 9000 watts is the absolute minimum for your BK and that will pretty much max out a standard 50 amp, 240 vac GFI breaker. I wish I could put two 5500 watt elements in my BK and HLT but my breaker won't safely allow it. If you are going to use a HERMS, you will need 9000 watts in your HLT as well.