computer lab

[clipperclipper]

Dear Mike,
I'm an electrician with little of experience, just 6 years in the trade. Here is my dilemma, I have a call from a school lab that put 20 computers on a single 20 amps circut. And of course this would trip the breaker when all 20 computer are used. So when I got there I would add another circut to it. So now 10 computers are on one circut and 10 computers are on the other circut. This work fine. There are no problem of its tripping. But here is the question, a co-worker wanted to put a 30 amp breaker inside 100 amp service panel, ran it to a junction box and splice it to where one hot, one nuetral, and one ground to 10 computer and the same to the other 10 computers. At the time I told him this would'nt be a safe application. I'm I right or wrong?

[ November 21, 2005, 11:24 PM: Message edited by: clipperclipper ]

 

[celtic]

Re: computer lab

You're asking this question with "just 6 years in the trade"?

Be honest.

 

[iwire]

Re: computer lab

Originally posted by clipperclipper:
But here is the question, a co-worker wanted to put a 30 amp breaker, ran it to a junction box and splice it to where one hot, one nuetral, and one ground to 10 computer and the same to the other 10 computers. At the time I told him this would'nt be a safe application. I'm I right or wrong?

It would be a code violation to protect 15 or 20 amp duplex receptacles with a 30 amp breaker.

Take a look at 210.21(B)(3) sometime soon.

 

[iwire]

Re: computer lab

For what it's worth if I had to feed 20 PC locations each with monitors I would be thinking of at least 5 circuits maybe more, but that's just a personal choice.

 

[petersonra]

Re: computer lab

it would be ok if he put 20A OCPD in the hot leads inside the junction box feeding the 10 outlets.

 

[wpaul29]

Re: computer lab

iwire is right. What I would have done is just have one computer and monitor on and take amp readings. Then multiply what you get by how many computers you have. Then you would have a better idea of the total load and how many circuits would be needed. No offense but most apprenticeships are 4 or 5 years long.A qualified journeyman would be able to answer that question with ease. Have you had any formal training?

 

[hurk27]

Re: computer lab

it would be ok if he put 20A OCPD in the hot leads inside the junction box feeding the 10 outlets.

If the original circuit had a 20 amp OCPD on it which would lead me to believe that the circuit conductors are only rated for 20 amps then a 30 amp breaker would not be allowed to protect this circuit in the first place. And to put a breaker in a junction box? How would that ever be code compliant or even UL listed? :roll:

[ August 08, 2005, 02:17 AM: Message edited by: hurk27 ]

 

[jimwalker]

Re: computer lab

What many get confused about on computers is that the loads vary depending on what they are doing.I too agree with Bob on this one.At a max i might put 6 on 1 circuit but prefer no more than 4.If you put 10 on your looking at 240 watts per station.Thats asking for a problem.With computers being out dated before they leave the store you need to plan ahead on its replacement that likely will need more watts.

 

[petersonra]

Re: computer lab

Originally posted by hurk27:

it would be ok if he put 20A OCPD in the hot leads inside the junction box feeding the 10 outlets.

If the original circuit had a 20 amp OCPD on it which would lead me to believe that the circuit conductors are only rated for 20 amps then a 30 amp breaker would not be allowed to protect this circuit in the first place. And to put a breaker in a junction box? How would that ever be code compliant or even UL listed? :roll:

If they ran the correct size wires to the junction box it would not be an issue. I don't recall the code requiring CBs to be in a panelboard. QO and QOU breakers can be mounted on a flat panel. I do it all the time. The QOU breakers come with a panel moutning bracket, the QO breakers you have to buy a little doohickey to do this.

 

[iwire]

Re: computer lab

Possible if you keep the JB or other box readily accessible.

But let's not re-invent the wheel for some simple standard branch circuits.

 

[catchtwentytwo]

Re: computer lab

Code issues not withstanding, the "breaker in the box" creates a potential troubleshooting nightmare. It could also be a safety issue when unqualified folks eventually try to reset the beaker themselves.

Might as well install a visible subpanel.

 

[petersonra]

Re: computer lab

Originally posted by catchtwentytwo:
Code issues not withstanding, the "breaker in the box" creates a potential troubleshooting nightmare. It could also be a safety issue when unqualified folks eventually try to reset the beaker themselves.

Might as well install a visible subpanel.

I agree it is somewhat cheesey, but it does not appear to be prohibited by the code, presuming it is done correctly.