laundrymat renovation

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benwieland

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I have a customer that is removing 10 single load gas dryers and replacing with double loaders. the nameplates on the existing dryers are 8.5A , 5.5A at 120V and 208V respectively. And the new comming in to replace these are all 120V at 19.8A. Now I know how to calculate the branch circuts in 430 but I beleive the MCB at the service (200A) is not adequate to support the new equiptment. This is where it gets tricky. This place is about thirty years old and was originally just a laundrymat but about 10 yrs ago they added a 3 bay car wash and ran a 100A feeder to a sub-panel in the pump room. They also have two other 100A sub panels, 1 for the washers and 1 for the dryers. Now as far as determining if the existing service will make due I have recorded all the nameplates of all equiptment and counted the recp and measured the sq ft but I am not sure what figure I would use for general lighting and what if any demand factor to apply.
 
Re: laundrymat renovation

I'd use the 1/2 VA per square foot, per the General Lighting table for "Halls, Corridors, etc."

A better solution might just be to look at the existing lights, or turn them all on and check with an ampclamp to determine the lighting load for the halls and laundry area.

You wouldn't need to calculate a general lighting load for the car-wash area, just look/ampclamp the existing fixtures.
 
Re: laundrymat renovation

BEN: Assuming that the lighting load does not change, the connected load based on the nameplate data provided for existing 10 dryers is: 120V x 8.5A x 9 = 21,384VA. 21,384VA/360 = 25.5A. 19.5A + 25.5A = 34.6A

A phase = 25.5A, B phase = 25.5A, and C phase = 25.5A + 19.8A = 34.6A. Add the lighting load to these values distributed over the 3 phases.

The connected load for the new dryer loads is: A phase = 59.4A, B phase = 59.4A, and C phase = 79.2A. Add the lighting load to these values distributed over the 3 phases. The calculated load requires you to use the sum of the FLA of the motors plus 25% of the largest which results in 84.15A on the phase with the greatest load. Don't forget to add the lighting load at 125% because it is a continuous load.
 
Re: laundrymat renovation

Just some technical info, the Code requires the motor load calculation requires that you use the ampere values for motors based on horsepower and voltage in the table in article 430.
 
Re: laundrymat renovation

In my opinion if you want to change the service do all the calculations that John C. has suggested and you will be well above 200 amps.

If you do not want to change the service IMO your only chance is to get the 1 year demand loads as hardworkingstiff suggested.

Look at 220.35 Optional Calculations for Determining Existing Loads and follow the method shown there.
 
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