Load Letter

Status
Not open for further replies.
A

admiralporklung

Member
Location
Front Royal
My company has been awarded its biggest job to date, a movie theater. 50,000 sq ft of new construction. We have the skills and the manpower to do it. We are very excited.

The GC has asked us to fill out the load letter for the POCO. I thought that this was the job of the engineer/designer.

I am struggling to fill it out. For example what is BHP?
 
admiralporklung said:
My company has been awarded its biggest job to date, a movie theater. 50,000 sq ft of new construction. We have the skills and the manpower to do it. We are very excited.

The GC has asked us to fill out the load letter for the POCO. I thought that this was the job of the engineer/designer.

I am struggling to fill it out. For example what is BHP?
Click to expand...


As in Brake Horse Power of a motor?
 
admiralporklung said:
It is on the AC Unit schedule. I think that it is Base Horsepower. But the load letter wants very detailed information about all motors on the job, including fractional HP motors such as fart fans.

I'm dying here.

Dave
Click to expand...


746 watts per hp

Horse power three phase = volts times amps times efficiency times power factor devided by 746

Single phase = volts times amps times efficiency times power factor devided by 746
 
Gregg Harris said:
746 watts per hp

Horse power three phase = volts times amps times efficiency times power factor devided by 746

Single phase = volts times amps times efficiency times power factor devided by 746
Click to expand...


I know the basic electrical formulas like the one given here. But, for the purpose of load on a natural gas RTU, does the BHP (presumably Braking Horse Power) of the fans cover the whole of the motor load?
 
Don't sweat the details on your load letter. Your approximation is good enough for the utility. They probably serve 100 theaters in their footprint and can predict what your demand will be better than you can.

The only time I've seen a utility load letter form that wants you to list all your motors on it was when the utility was offering rebates for energy saving motors. Most just want a generic breakdown like lights/receps/AC/largest motor.
 
To simplify just assume 1Hp = 1KVA.

By the time you convert Hp to KW, then try and add some unknown efficiency and power factor you've spent a lot of time for nothing.

The approximation is conservative, but at this stage it's better to be over than under.
 
kingpb said:
To simplify just assume 1Hp = 1KVA.

By the time you convert Hp to KW, then try and add some unknown efficiency and power factor you've spent a lot of time for nothing.

The approximation is conservative, but at this stage it's better to be over than under.
Click to expand...

It works the other way too. The form wants HP but AC compressors aren't rated in HP. Just put down the kVA on that line.
 
JoeStillman said:
Don't sweat the details on your load letter. Your approximation is good enough for the utility. They probably serve 100 theaters in their footprint and can predict what your demand will be better than you can.

The only time I've seen a utility load letter form that wants you to list all your motors on it was when the utility was offering rebates for energy saving motors. Most just want a generic breakdown like lights/receps/AC/largest motor.
Click to expand...

I agree - just give them something approx.

They usually use the same form for every job from a small office to a new factory. I think they just want to make sure you aren't going to install a 400 HP motor, and then blame them when it doesnt start.
 
Status
Not open for further replies.
Top