On Sunday, June 26, 2016 at 4:34:01 PM UTC-4, Ralph Mowery wrote:
In article ,
says...



As I pointed out.. the tanning beds operate for no longer then 20 mins. So that would be the maximum time spent above the 200 amp line. But I still would like a better answer as to how far past I can go before I start tripping the main. In earlier posts I read that only after a sustained amp draw of 3 hours would it trip. If this is true then I shouldnt be anywhere close to having a problem if I am only
doing 20 mins then a break then 20 mins etc. So could I go to 250 amps? or more? I understand what I am asking is pushing the rules, but would like a reasonable idea of how far past I can go. I want to purchase one more bed and if that puts me at 210-220 amps for 20 mins at a time, just want to know that I can do that without tripping my main etc.

Thoughts?

Forget about trying to push the limiits of the breaker. If you already
have a load of close to 200 amps, either forget the other bed or upgrade
the service.

You are not only pushing the limits of the breaker and may weaken it to
where it will trip at a lower current at a later time, you are chancing
over heating the wires feeding the breaker.

Looking at some typical tripping curves it could take from 1000 to
10,000 seconds if overloadded to about 120%. The more the overload, the
faster the tripping.

It is also the ammount of heat build up. If the box is cold as in the
winter time, the times will be longer and if hot as in the middle of
summer, the times will be shorter.

+1 to all that.

The OP is right at 200A with the existing 5 beds. The dryer makes it 216A.
Five beds, 200A, the beds are 40A each, so how can they add a couple of
new beds? Even one puts it at 240A/256A. And in line with what you're
saying about warming up, once tripped, if it's reset, it's going to trip
faster the next time. Doesn't sound good with a business with 6 customers.


Side note, I'm having a hard time figuring out where all this power is
going. That's 10KW for one bed. I've never been in one, but I thought
they put out UV, not a lot of heat. 10KW sounds like enough power to
start cooking you, similar power to a home oven.