Need help on Code for #6 awg wire......

[Jim gator]

I am currently installing electric tankless hot water heaters. I do a few condos but would like to do more. My limitations are the 1/2 metal conduit. The size will only allow me to pull #6 wire with #10 ground which limits the amps I can alott for the heater. I am currently using a model that draws 47 amps. I would like to use a model that draws 65 to 71 amps. I know from NEC 310.16 that under 100 amps I must use the 60 celcius column. I have also discussed using several types of other wire like sa, fep and others with a higher ampicity with my local electrical official who always says no. I told him i would be using a small 125amp rated subapanel with breakers which I thought would allow me to use the higher rated #6 wire. I was using this from NEC "Conductors terminating on independent pressure connectors on a bus, are permitted to be sized to the temperature rating of the connector. For example, if 90?*C pressure connectors are located on busbars, feeder conductors have a THHN insulation can be sized to the 90?*C temperature column of Table 310.16."

Can anyone tell me why he is telling me this because he will not explain except to say he knows you can't. If it is possible can you tell me what wire you use and why? If not possible tell me why?

Thx

 

[charlie b]

Jim, you are over your head on this one. You seem to be familiar with some of the terms, and have read some of the related NEC articles. But it is clear that you do not understand the basics of electrical theory and the essential nature of installation rules. That is perfectly normal and to be expected, since electrical installation is not your profession.

That said, forum rules do not allow us to assist a person who is not an electrician to perform electrical installation work. Ask the electrician with whom you work to join the forum, and we can answer that person's questions. Per forum rules, I am closing this thread.