Thread: Box fill question and DC motor question.

1. Box fill question and DC motor question.

Hi there!, please I need to solve this two questions, I having trouble with them, looks very simple but there is something I cannot find right. Thank you !!!!!

1. What size of box is required for two #6 conductors, one #10 ground that leave the box, one #12 ground and two #12 conductors, the #6 conductors has internal clamps and the #12 has external clamps.
2. what is the efficiency of one 5HP/230 DC motor ?

2. Junior Member
Join Date
Jul 2012
Location
Simpsonville, South Carolina
Posts
1

Box Fill Calculation

I gave your question about box fill a shot; Let me know what you think.

TABLE 314.16(B) ALL OF ARTICLE 314.16

2- #6 conductors = 10 cu in
1- #10 ground = 2.5 cu in
2- #12 conductors = 4.5 cu in
1 internal clamp (#6) = 5.0 cu in
Total: 22 cubic in = 4 x 2 1/8 square box

for your motor question, I don't think there is enough info. Efficiency = output of true power/ input of true power

the true output of a DC 5HP, 230v motor is: 1hp = 746watts; 5 * 746 = 3,730watts

Let me know if this helps.

3. Junior Member
Join Date
Jul 2012
Location
Arizona
Posts
1

Dc motor effciencies

I have an old American Electician Hand book and it gives some approximate Eff: 5HP at half load 77% Full load 81.5 % hope this helps some

4. Originally Posted by AZBob
I have an old American Electician Hand book and it gives some approximate Eff: 5HP at half load 77% Full load 81.5 % hope this helps some
I'm pretty ancient and I've dealt with quite a lot of DC drives. Not very often as small as 5HP but those figures seem like a reasonable basis for calculations.