Article 430 Part V

[djtazjr]

I have been reading Article 430 of the code and came to the section of Motor feeder short circuit and ground fault protection.

Something has puzzled me in 430.62 (a). What I am not understanding is how this code applies to the number of motors that the feeder will have on it along with specific of 440. 22 (a).

What I am trying to say is; Does the sum of 440.22(a) need to be added to the sum of the largest rating or setting of the branch-circuit shor circuit and groundfault protection device plus the sum of the full load currents?

I am rather confused.

As an example:

Determine the minimum required branch-circuit short-circuit and ground fault protection and the feeder protection for 3-2hp 230v 1ph, 4-3/4hp 230v 1 ph motors; 5-208/230v Pool heater with hermatic compressors and 37 amp load current each. And how about putting 8-300 watt pool transformers with the pool equipment panel along with 35 step lights each with 2amps of operating current each. On a 208v 3ph 4wire feeder.

I am using a real installation for an example. Any help with understand the code requirements of properly sizing the feeders for the panel and protection is greatlyh appreciated.

 

[Pierre C Belarge]

Take a look at 430.63.
This section refers you to other sections which also refer you to additional sections [see 440.22(B)(2)] and in turn you will be moving between more sections in 430.
My advice, write the different section numbers and their related info down.
Without experience, it will take time and patience to muddle through this one.

 

[websparky]

I would be glad to figure the load if the information was accurate!

A 208V service will not supply 230V loads.
And, 5 - 37A compressors?
And 70A of 120V lighting? In a pool?

If this is someones idea of a test question, it stinks!

If this IS a real load, get the proper info!

 

[iwire]

A 208V service will not supply 230V loads.

Sure it will.

If you look at a motor and it says 208-230/460 your good to go.

The last motor I wired was tagged 200 volts and that is being supplied from 208.

 

[dahualin]

Article 430 part V is talking about how to size the protective devices against overcurrents.

The electrical information of your example is not accurate.

Here is a simplified example based on your information. 2-2hp 230 1ph; 2-3/4hp 230 1ph; 2-hermetic comressor with 37amperes rated load current.

Check Table 430.248 for FLA of single phase motor
FLA(2hp): 12 amp
FLA(3/4hp): 6.9 amp
Rated load Current(compressor): 37 amp

Apply 430.52 for the largest motor (assuming inverse time breaker): 250%x12=30 amps

Apply 440.22a for the compressor: 175%x37=64.75 amp the protective device for the compressor will be 70 amps.

Since 64.75 amp is bigger than 30 amps, the compressor is the largest load (motor or compressor).

The protective device for the feeder shall be the largest rating or setting (70amps) of the protective device for the largest load (motor/compressor)(only count one) plus the sum (2x12amps+2x6.9amps+37amps) of the full-load currents of the other motors of the group. that is 70+2x12+2x6.9+37=144.8 amps. The next size up will be 150 amps.

Hope this help.

 

[djtazjr]

Much help! Thanks!

Oh and if this was a "stink" question then what is the purpose of this forum?

A question only "stinks" if you like it sit in you mind and rot!

Thanks again!