75 kva transformer

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jeremy.zinkofsky said:
You only need to worry about continuous duty if the tanning beds have an integral motor, which i doubt they do. They should be a linear load like a heating element or a light bulb and should consume power according to the temperature setting. So at max "tanning" the machine will draw 37A.

I would recommend that you meter the existing panel for 30 days in accordance with the NEC to determine the actual load. If you have enough capacity for the tanning beds + 125% then its all good. If not, you would need to upsize the service or bring in a second service and panel.
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I haven't seen a new tanning bed/booth for quite some time, but the ones I have seen have a cooling fan and several VHO electric discharge lamps. Though the older ones I have been around have magnetic ballasts, I would guess newer ones use electronic ballasts which would be non linear loads. User doesn't get tanned from temperature they get tanned from the UV light.
 
kwired said:
I haven't seen a new tanning bed/booth for quite some time, but the ones I have seen have a cooling fan and several VHO electric discharge lamps. Though the older ones I have been around have magnetic ballasts, I would guess newer ones use electronic ballasts which would be non linear loads. User doesn't get tanned from temperature they get tanned from the UV light.
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Sorry, i am not a technical expert on tanning bed construction. The point was that tanning beds are most likely not considered a "motor" load per NEC. This would need to be verified of course by the electrician.
 
jeremy.zinkofsky said:
Sorry, i am not a technical expert on tanning bed construction. The point was that tanning beds are most likely not considered a "motor" load per NEC. This would need to be verified of course by the electrician.
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I would call it an appliance, with a combination of motor load and other load. Nameplate should tell you minimum branch circuit ampacity needed - however it won't necessarily tell you demand characteristics which is what we are really looking for for service/feeder calculations here.
 
If they are 1ph to neutral, 37A on each leg x 5 = 74, 74, and 37. 3ph would be 175, 175, 175. L-L would be 111,111, 148 (I think - doing this in my head).

So

a) you need to know what the beds are wired for (120V, 208V 1ph, 208V 3ph)
b) what the existing demand is on the service
b) what size is the service

The POCO may not do squat about the 75kva xfmr that is there. The 50kva that serves this house and others is fed from a 20kV primary and a 75A primary fuse (yes, that's 1494kw) . They (Dominion) are obviously not worried about what loads are happening on the secondary side.

istm if one sat in a tanning bed for 3+ hours at full song, they'd be bbq. iow, they are not continuous loads.
 
My best guess is the mentioned 37 amps is @ 208 volts single phase, so about 7700 VA per unit. 5 units is 38500 VA.

Seems like a lot of energy for a tan, but there is probably a lot of wasted heat generated. If it were 208 three phase - that would be 13.3 kVA, just to get a tan, don't think you would spend more then 10 minutes at a time in that kind of treatment, which NEC doesn't exactly address but the load diversity wouldn't be that high in that sort of situation as the clients would spend more time undressing/dressing then they spend in the booth.
 
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