Now there are 6 conductors in the conduit, I will have to de-rate them asper Table 310.15 (B) (3) (a). My question is do I use the 90 degree rating or use the 75 degree rating?

My other question is about article 230.42. I looks like the ampacity of the services conductors is determined by a calculated load and not the size of the two service disconnects, does that sound correct?

I hope that this makes sense.

Any information will be very helpful. Thanks, Bill ]]>

Plant has a 1200HP pump motor served with 600 volts.

For a temporary maintenance period the plant source will change to a better transformer providing the power but a great deal farther away from the plant. Calculations suggest the voltage drop on motor start will affect other customers.

This motor does not have a VFD or soft start package.

The plant has suggested they can open all valves, allow the motor to start no load and significantly reduce the estimated voltage drop on the line.

I don't agree.

I have done many test demonstrating load affecting the running amps of a motor, but contend that starting currents will be the same. ]]>

The Electrical required is a 40amp 240v circuit.

The unfortunate thing is the Town home only has a 60 amp service and is group metering.

The home has A/C (3 ton) and is about 1200 Sqft. all gas appliances. I calculate just under 60 amps load. So I told the lady a no go.

I get a call from her telling me that another Electrician says no problem we can do this with your 60amp. panel you have.

Question is do we ignore the calculations because we feel the actual load will never exceed the 60amp. ]]>

I checked panel and no power one side. The owner then turned the switch on a 240 volt wall heater and all the lights came back on.

I checked the panel and power on both sides. I turned off the wall heater and the lights went off again.

Turned wall heater on again and power on both sides.

Any ideas? ]]>

Would it be ok to run Underground 750mcm

Would require 2 manhole I guess @ 550, and 1100 feet. 120/208volts. 3 phase. Hangers don't use much.

They asking for about 3 - 20 amps circuits per bay ( 12 bays per building, 3 buildings) 300 long by 50 wide, 20 feet high.

1ckt for 2 - 150 watt HID lights

1ckt for 1hp Bifold door.

1 ckt for GFI general use

Each building would get 7- 400 watt MH wallpacks.

Plan on feeding the 3 buildings. ( 1 - 150 amp MB panel 1 phase) per building.

Service from street. Will be 3 phase 400 amps. But the Load calc will definitely can diversify, Due to only a fraction of use in the hangers. What diversify % I would have to estimate.

From the 400 amp Service to Each 150 amp 1phase MB panel - Run 2/0 about 200 feet each

Then from 150 amp 1 phase panels to the (12) Small subpanels per blg. Fused @ 40 longest being 300 ft to last bay.

Was calculatings voltage drop from street to farthese panel.

(1675FT) -From over head poles to Main Blg service ( #750 MCM) 400 amp-3phase -120/208 #2/0 -150 1 phase panel( 200 FT) , + 150 mb panel 1 phase to farthest Panel #6 (300ft) ]]>

Question 1:

Can Analog 24VDC vs Discrete 24VDC vs Comm (Ethernet) be routed in the same conduit?

Question 2:

Can Analog 24VDC vs Discrete 120VAC be routed in the same conduit?

Question 3:

Can Discrete 120VAC vs Comm (Ethernet) be routed in the same conduit?

Question 4:

Can Analog 120VAC vs Comm (Ethernet) be routed in the same conduit?

Appreciate your help in advance.

Thanks ]]>

My concern is that the switchboard isn't rated high enough. ]]>

I need to size a diesel genset for a small country store.It has a single phase 300a service with plenty of 240v refridgeration loads,a mix of 120 and 240v coooking equipment,AC/heat,lighting and other typical 120v loads.

With all of their equipment running on a busy summer day(AC and fridge loads not cycling because of summer heat),A phase pulls approx 150 amps and B phase pulls approx.170 amps.

The client wants an ATS and does not want to do any manual load management by shedding loads via the Main Breaker panel or to add loads by turning appliances on that aren't needed for use.I believe there is a potential problem because diesel generators have a minimum rated load to be observed in order to prevent "wetstacking" of the motor which could cause costly maintenance. I believe that the minimum rating is typically 30% of the maximum rating.

My initial calculation is 247v times 170amps for approx. 42kw.I would then oversize this to 50kw to allow for start up of fridge compressors and fans.

Now I would like to do a minimum load calc for the business when it is not open and is using far less cooking equipment,lighting,etc.

I want these calculations for max and min load to be as accurate as possible and am hoping the good members here could steer me in the right direction...

More specifically,I would like to know how to count the 120v and 240v loads separately? I believe that this would be more accurate than multiplying the amp draw on one leg by the measured voltage.

thank you all in advance for any advice and opinions.... ]]>

I don't have much experience with arc fault breakers, but a friend of mine says he has a lot of problems with them when used on old romex. He even had a recent problem with a brand new circuit connected to a brand new refrigerator.

What are the chances of this working: Use existing wiring in a house built in say 1959, replacing all the devices and fixtures and using a combination arc fault ground fault breaker. If the wiring passed a megger test could it be assumed to work fine for a while?

The above example is for bedroom and living room wiring without a ground. The kitchen has a ground wire. I wondered if we could replace all the non grounding type receptacles with grounding type and protect it with the combo breaker. Any thoughts?

Thanks ]]>