computer loads and a stickler Inspector

[glene77is]

Hurk,
Good approach.
Also, I suggest that the computer power supply may have high harmonic content, expressed possibly by a Power Factor number,
which should be entered into the calculations.

Conferring with Rattus about RMS concepts, and applying it here,
I think an analog RMS circuit to produce running RMS numbers for V(rms) & I(rms), collected by a data logger, and run through a computer program to produce a P(avg) (VA or an RMS value) could show the real power consumed by this circuit over time with many dips & spikes of used power.
This isn't going to happen !

IMHO, at best,
the inspector is stepping out too far, to cover something he is reading about.

 

[George Stolz]

Doesn't the NEC and an inspectors jurisdiction stop at the premises wiring?

If this is not correct please give me a code reference where an inspector can tell you what you can or can not plug in.

If this was hard wired I would agree. But it is not.

Mike, consider the following:

400.7(B) Attachment Plugs. Where used as permitted in 400.7(A)(3), (A)(6), and (A)(8), each flexible cord shall be equipped with an attachment plug and shall be energized from a receptacle outlet.

If the code stopped at the receptacle, then this sentence would be a paradox.

410.62 would be referencing a luminaire that is outside the scope of the NEC. 422.16 would be referencing a void.

Is there no range or dryer in a dwelling unit if they are cord and plug connected? How do we calculate their loads by 220? Do we just leave them out?

Point is just that. We have no idea what will get pluged in.

Well, if you've got a series of desks with little bays all dedicated for computer towers, with the towers on site and pictures of little computers all over the prints and elevations, then I suppose one could take a leap and assume computers are getting plugged in, ey?

If this inspector is stupid enough to not know the name plate is just a peak then he needs find another job.

If the NEC is too stupid to have an allowance built in for this, or a method for determining how to size these circuits expressly spelled out, then I suppose we can blame the NEC for being incomplete and try to remedy that.

As it stands, 220.14(A) is pretty clear:

(A) Specific Appliances or Loads. An outlet for a specific appliance or other load not covered in 220.14(B) through (L) shall be calculated based on the ampere rating of the appliance or load served.

I don't have all the answers, but I am not seeing a real concrete code answer to get the OP out of the problem. As I see it, it's not the electrician's problem anyway, it is the engineer's. Let them duke it out.

 

[jxofaltrds]

George

I think that the 400.** & 410.62 references are more on the perminent or premises wiring side. Items fastened in place. I agree with those codes.

The dryer and range fall under 220.14(A). Agreed.

I do not see a computer or a screen being a specific load under 220.14.

So I could not plug my sweeper (vacuum cleaner) into a circuit if it had other loads?

Would you turn me down if you saw boxes and boxes of xmas lights in my garage? Understand?

Watch Mike Holts video that I posted above.

 

[George Stolz]

George

I think that the 400.** & 410.62 references are more on the perminent or premises wiring side. Items fastened in place. I agree with those codes.

400.7(B) absolutely does not. It references 400.7(A)(3), which clearly references "portable luminaires, portable and mobile signs, or appliances." Portable is not fastened in place.

A luminaire installed according to 410.62 may or may not have a plug cap, but the ones that do have a plug cap will plug into a receptacle, and will still be governed by 410.62.

The dryer and range fall under 220.14(A). Agreed.

I do not see a computer or a screen being a specific load under 220.14.

Help me out - what generates the difference in your perspective between the two?

So I could not plug my sweeper (vacuum cleaner) into a circuit if it had other loads?

Would you turn me down if you saw boxes and boxes of xmas lights in my garage? Understand?

Are the vacuum or Christmas lights on the prints? I'm not being facetious, stone serious. There are all kinds of lights out there. If I intended to have cord-and-plug-connected rope lighting as my required lighting for one thing or another (210.70(Take Your Pick)), would the receptacle be considered a switched receptacle or a lighting outlet? 210.70 makes clear distinctions about where and when it'll allow a switched receptacle to serve in place of a lighting outlet. Stick that switched outlet in the ceiling, swing a low-bay near it, and suddenly things go sideways, don't they?

Watch Mike Holts video that I posted above.

A scope argument is very broad, contrasted with the specifics we're getting into here.

I used to have a very cut-and-dried opinion about this - that the receptacle marked the end of the premises wiring. A discussion here fractured that certainty for me, and left me to realize that there is a discontinuity throughout the book that gives 90.4 another foothold in our lives. If this inspector is sitting in that crevice, it's because the code is not entirely clear on this, and 90.4 says that his office makes the final call.

 

[stevenje]

I don't have all the answers, but I am not seeing a real concrete code answer to get the OP out of the problem. As I see it, it's not the electrician's problem anyway, it is the engineer's. Let them duke it out.

You hit the nail on the head George. Push the problem upstairs.

 

[Jim W in Tampa]

OK ,i agree if its on the print that you have a computer but unless it says make and model number it means nothing as you have no values. Are we to assume the computer will be there forever ? Why would an inspector even try to add up the load. Solve the problem and remove the computer and tell him they are buying ones that draw less amps. Now he has no choice but to pass it.
I have wired up many power poles without knowing what computer they will install. And guess what , never had a problem.

 

[George Stolz]

OK ,i agree if its on the print that you have a computer but unless it says make and model number it means nothing as you have no values.

...unless they are sitting there awaiting inspection.

Why would an inspector even try to add up the load.

You're saying inspectors have no business doing or questioning a load calculation?

I have wired up many power poles without knowing what computer they will install.

Often times in our business, ignorance is bliss.

 

[e57]

~~~Well, if you've got a series of desks with little bays all dedicated for computer towers, with the towers on site and pictures of little computers all over the prints and elevations, then I suppose one could take a leap and assume computers are getting plugged in, ey?

Sometimes a furniture over-lay shows up on certain RCP's - this doesn't mean I need to supply power to the couch... And if I have a bunch of cubicles on a set of plans - doesn't mean there will be a computer of a specific size in each. Or a monitor in each of a specific size, or a desk lamp, Fax machine or printer, cell phone charger, pencil sharpener, or an ipod docking station. People will generally plug this or that in whatever is generally available. Calling "computers" a specific load IMO is a stretch.

If the NEC is too stupid to have an allowance built in for this, or a method for determining how to size these circuits expressly spelled out, then I suppose we can blame the NEC for being incomplete and try to remedy that.

As it stands, 220.14(A) is pretty clear:

(A) Specific Appliances or Loads. An outlet for a specific appliance or other load not covered in 220.14(B) through (L) shall be calculated based on the ampere rating of the appliance or load served.

Following that reasoning - whatever the end user plugs in from time to time is a "specific appliance or load"? IMO these are general use receptacle that happen to also serve computer and monitor loads - and everything else.... 220.14(K) fits the application - and if it does not it needs to be re-written. And I'm sure we all know that in some cases it is not adequate. (Especially with middle aged women and their space heaters....)

That said - I have been in this exact same position about 6 years ago. An inspector asked how many circuits I fed a bunch of cubicles with. A: three... He went on a big tizzy thinking that was too many cubicles for just three circuits.... And he may have been right had I not asked in a meeting with the client about how areas would be used. This area was only for transient sales guys who show up with a laptop and briefcase - even if all of them we used, three circuits would still be more than adequate.

I don't have all the answers, but I am not seeing a real concrete code answer to get the OP out of the problem. As I see it, it's not the electrician's problem anyway, it is the engineer's. Let them duke it out.

Unless I missed something - I did not see an Engineer mentioned by the OP??? Sounds like an EC vs. EI battle.

 

[jxofaltrds]

George

Luminaires are adressed in the code. Computers, TVs, radios, etc. are not.

The receptacles are for 'general' loads not specific.

The dryer and range are specific loads.

We can use the kitchen arguement used before. I could have a 50' counter with two circuits and lets say 14 receptacles on that counter. Would you make me add additional circuits?

Does this help?

"You're saying inspectors have no business doing or questioning a load calculation?"
Yes.

Thats for the plans examineer.

BTW was this installed per the approved plans. Totally forgot about that.

 

[Jim W in Tampa]

...unless they are sitting there awaiting inspection.


You're saying inspectors have no business doing or questioning a load calculation?


Often times in our business, ignorance is bliss.

I have never seen computers sitting around a construction site. That would be asking for theft and getting dirt in them.
Inspectors have no right to question plug in items unless they are on the stamped set of plans. Never seen prints saying model or make so is no way as an electrician that could know the load. Your living room could have a high demand TV, audio equipment, computer and could easily come to over 15 or 20 amps. Can he make you add a circuit ??? No big brother can't go there.
As i said solution is just remove the computer to shut him up.
If he does not know more than that about computers then he needs go back to school.

 

[kwired]

If the circuit is overloaded that would mean owner would be calling you back asking why circuit breaker keeps tripping. That is a problem between you and the owner and not the inspector. This does happen from time to time because you did not know what will be plugged in.

People with experience wiring offices know what kind of equipment is common at certain types of workstations. They also know that a lot of women will plug in a space heater at their personal workstation. That alone usually requires at least one circuit per individual workstation in their minds but if you don't know for certain the heater will be there it is not addressed in the NEC.

I have seen computer labs in schools with quite a few computers on one circuit - never any problem holding circuit breaker. In general a personal computer is idle more than it is working, certain types of software environments can put more demand on them however.