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Old 05-12-2017, 08:27 PM   #1
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Default My first load calc

Are there any cookie cutter forms/websites you guys use for doing in depth load calculations.. I'm doing my first one and something to follow would be a big help


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Old 05-12-2017, 08:30 PM   #2
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You lazy dogg.
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Old 05-12-2017, 08:37 PM   #3
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Originally Posted by telsa View Post
You lazy dogg.


Lol , I've honestly started it already using the code book .... it being my first one , it sure would be nice to see some sort of base worksheet... it involves large Commercial kitchen equipment and I want to check my work multiple times


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Old 05-12-2017, 08:37 PM   #4
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I doubt such a thing exists due to the complexity of each occupancy and bouncing between tables you can or can't use depending on certain loads.

Residential is the worst due to being able to derate your derates in certain circumstances.

Best way is to go slowly page by page in 220 breaking down each load by article and balancing your phases as you go (including neutrals).

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Old 05-12-2017, 08:42 PM   #5
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For resi I just use this spreadsheet: https://www.mikeholt.com/documents/c...lculations.xls
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Old 05-13-2017, 05:52 AM   #6
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Quote:
Originally Posted by HackWork View Post
For resi I just use this spreadsheet: https://www.mikeholt.com/documents/c...lculations.xls


Nice!


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Old 05-13-2017, 06:32 AM   #7
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Quote:
Originally Posted by Glock23gp View Post
I doubt such a thing exists due to the complexity of each occupancy and bouncing between tables you can or can't use depending on certain loads.

Residential is the worst due to being able to derate your derates in certain circumstances.

Best way is to go slowly page by page in 220 breaking down each load by article and balancing your phases as you go (including neutrals).

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Really?
I can smash out a residential load calculation in less than a minute.
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Old 05-13-2017, 08:45 AM   #8
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Originally Posted by WronGun View Post
Nice!


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That is older than I am, so hopefully it still works.

It's nice because you can add your company name to it and a job name. There is a town here that wanted a load calc when doing service upgrades, so I used to use that spreadsheet to include a load calc with every service upgrade permit application I submitted. All the inspectors liked it and a few made comments about how they didn't need to look closely at things because they are sure I did them right, based off of my going above and beyond with the load calc.
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Old 05-13-2017, 08:53 AM   #9
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Quote:
Originally Posted by Suncoast Power View Post
Really?
I can smash out a residential load calculation in less than a minute.
Congrats.

I'm talking about commercial and industrial sizing load, wire and conduit from xfmr to each circuit including sizing additional transformers, motors and neutral loads.

My 3 year old can do resi calcs.

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Old 05-13-2017, 09:04 AM   #10
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Quote:
Originally Posted by Glock23gp View Post
Congrats.

I'm talking about commercial and industrial sizing load, wire and conduit from xfmr to each circuit including sizing additional transformers, motors and neutral loads.

My 3 year old can do resi calcs.

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In all fairness, you did say "Residential is the worst" which I also kinda wondered about.
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Old 05-13-2017, 09:13 AM   #11
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Quote:
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In all fairness, you did say "Residential is the worst" which I also kinda wondered about.
I meant like a multi family complex with different buildings (multiple xfmr calcs) and occupancies.

Say a residential over commercial with different occupancies downstairs to calculate different based on different lighting loads.

My bad.

As CS says.. I digress....

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Old 05-13-2017, 09:16 AM   #12
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Quote:
Originally Posted by Glock23gp View Post
I meant like a multi family complex with different buildings (multiple xfmr calcs) and occupancies.

Say a residential over commercial with different occupancies downstairs to calculate different based on different lighting loads.

My bad.

As CS says.. I digress....

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I see what you're saying, makes sense.
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Old 05-13-2017, 09:48 AM   #13
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Originally Posted by HackWork View Post
I see what you're saying, makes sense.
Here's an example that was used on my supervisors test.

Other questions are

What is the load in, in amps, on the grounded conductor for the office service

Same for multifamily building

What is min feeder conductor size for a dwelling unit using THWN-2 aluminum wire

What is minimum service rating for the multi family building if using the optional method.

What is the feeder neutral load in amps for each unit

Etc...

This is a good practice calc Wron

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Old 05-14-2017, 01:28 PM   #14
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this isn't that easy for commercial. Do you guys do all your commercial load calcs yourselves? It just seems being my first time a mistake could cost me large on this type of job. Following the code book , but my numbers dont seem right...should i hire this out?

A commercial kitchen where everything could very well be running at the same time, along with lighting, receptacle and HVAC loads im looking at 325A with the potential for future additions, Im figuring 400Amps....

This just got a whole lot complicated especially when the service is 2'' underground pipe, This may put me out of this job because now it seems i may not be a big enough contractor to handle this

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Old 05-14-2017, 01:58 PM   #15
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Aren't you just starting out? One man?

If you're not comfortable with it, you may want to reconsider this job.
I don't think there's a guy on here that would look down on you for it, we've all been there.
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Old 05-14-2017, 02:05 PM   #16
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I am just starting out...But this has the way its been this year....Ive been jumping in and grinding it out until i figure it out and get it..... And all those situations that were stressful are now a walk in the park because i never walked away. Im looking at this situation the same way, if i take it on the next one I will be experienced. I have the resources to pull it together....

Ive figured and designed the whole branch circuit layout...

Now that I just received more information on this job regarding the service. I need to make sure before i tell the GC we have a serious problem.

I didnt really do much calculation regarding the load...I have a list of equipment that may very well be running all at the same time day in and day out. I added up the amps and then did load calcs for the lighting and receptacles by SQ', then figured HVAC and left room for future expansion.

which is why i came up with 325 which im upping to 400.....This is a issue with a 2'' underground pipe
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Old 05-14-2017, 02:31 PM   #17
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It sounds like you're off to a really good start and I applaud your ambition for taking things head on. What you're doing isn't easy, I know first hand.

It sounded like you were apprehensive about taking on this job because of the size of your operation. All I meant is that sooner or later you may have to say no, and there's nothing wrong with that.

Growing too fast can be a killer, many small shops find themselves with hyper-extended credit, and little to no capital real fast this way.

What ever happens good luck with it.
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Old 05-14-2017, 03:17 PM   #18
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Did u do the calc page by page like I said in Article 220?

It looks intimidating at first but if you break it down step by step it simplifies it big time.

Lighting make sure it's all at 125%
Recep
AC heat
Equip

Why are you stuck with only a 2" conduit?

This is an existing building retrofit?

If it's 3 phase make sure you are diving kva by square root not the voltage.

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Old 05-14-2017, 03:21 PM   #19
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Default My first load calc

Yes , I did a load calc... with all the codes and rules I'm not 100% sure I'm correct. It seems I figured larger....

but regardless that's my main coming up from the floor , even if I could get away with 325A Using copper I'm still undersized with my pipe.

Currently the main is 225A and I've added up 260A of equipment being installed in the kitchen... this is 100% rating of some pieces and 125% of a few others.

The code says 65% of more than 6 pieces of equipment in a non-dwelling kitchen which seems odd because my list of equipment could all very well be running together





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Old 05-14-2017, 03:26 PM   #20
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Quote:
Originally Posted by WronGun View Post
Yes , I did a load calc... with all the codes and rules I'm not 100% sure I'm correct. It seems I figured larger....

but regardless that's my main coming up from the floor , even if I could get away with 325A Using copper I'm still undersized with my pipe.

Currently the main is 225A and I've added up 260A of equipment being installed in the kitchen...

The code says 65% of more than 6 pieces of equipment in a non-dwelling kitchen which seems odd because my list of equipment could all very well be running together




What's your final kva?

And

What did u divide it by?

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