Electrical service size

[Mitch schiffer]

My electric company specified a specific style meter can and configuration with an internal cut-off. I opted to add a 400a fused safety disconnect before feeding the main panels.

I was specifically looking at your 320/200a quote. I thought the prices were too high.

RE the CT Cabinet, I see a bunch of various CT Cabinet configurations on eBay, but I'd have to research 600a service to say anything else. There are options other than eBay or the electrician, once you know what you need you can search the internet for a good deal. Most power providers publish the specs of service requirements in detail, if you haven't reviewed that, you might want to. If you have reviewed it, it should indicate what type of CT cabinet configuration you need. I would expect most of the cost to be the labor.

Good luck!

Thanks I will definitely check that out and see if I can find the specs for what is required.

[Mitch schiffer]

I run multiple (2 at most at a single time) 7.5hp machines at a time on my 100amp house feed with a 60amp branch to my shop and I have NEVER blown a breaker with all the fluorescent lights on and the electric wall heaters running. The estimates here are all over the place and most sound very outrageous. To me it sounds like you need REAL advice, not internet advice even if the internet advice is well intentioned. Talk to someone that knows what they are talking about!

Here is my "Internet" advice (worth every penny of what you are paying for it!):

From your figures it sounds to me like 320 amp constant draw 400amp service should be more than plenty... even with a 20hp belt sander, a 7.5hp something else and 90amp kiln all running at the same time.

Attachment 473067

Running a 20hp wide belt sander off a RPC should draw no more than 100 amps 230v 1ph at full load of a 36" wide board being hit hard with 40 grit, call it 120 amps for a bit of extra headroom. 40 amps for a 7.5hp machine run at max power (like an air compressor, a saw draws no where near half this much). 90 amps for a kiln in the process of heating up (after it has heated to working temperature it will only occasionally come on to keep it at working temperature).

120a + 40a + 90a = 250a

That leaves you 70 amps constant draw, 150 amps intermittent draw to run the rest of the house and still be under a 320amp constant draw. You should be fine with 400amp service, with the ability to intermittently draw 400amps if everything decides to all of the sudden start up simultaneously (You would have to switch the main breaker on with everything powered on to have everything start up simultaneously).

P.S. Power companies get pretty temperamental about unbalanced 3 phase service usage. If you are drawing 200 amps between legs L1 - L2 and 20 amps between L2 - L3 and 10 amps between L3-L1 the power company has to generate 200 amps of current on all 3 legs even though only one leg is drawing this much current. 200 amps 208v 3 phase isn't really anything for the power company unless they have a dozen other businesses all running the same lopsided legs. My father was an electrical engineer and I remember him showing me a 3 phase load balancer they constructed for one of their factories so they could switch 1 phase circuits between different 3 phase legs to balance the 3 phase usage. That was in Taiwan and the power on many blocks became much more stabile after they balanced the power usage of the factory.

Thanks for the internet advice. I actually did pay a electrician to do load calculations for me, but he didn't seem very thorough or honest really. If I remember correctly he came to 390 amps for mine and my wife's shop and 135 amps for the house and another 35 apms for the storefront. He wouldn't tell me how he came to these numbers. For these reasons I was hoping to get some information from others who may have had similar situations to choose how to proceed. I would rather not pay another electrician to do calcs for me again to have a similarly poor result. Im wondering if the guy who did it just wanted to up sell the more expensive service option. I am going to have another electrician give me a quote I have called 6 electricians. Out of that 4 looked at it and I actually have gotten quotes from 3.

[Michael Schuch]

Thanks for the internet advice. I actually did pay a electrician to do load calculations for me, but he didn't seem very thorough or honest really. If I remember correctly he came to 390 amps for mine and my wife's shop and 135 amps for the house and another 35 amps for the storefront. He wouldn't tell me how he came to these numbers. For these reasons I was hoping to get some information from others who may have had similar situations to choose how to proceed. I would rather not pay another electrician to do calcs for me again to have a similarly poor result. Im wondering if the guy who did it just wanted to up sell the more expensive service option. I am going to have another electrician give me a quote I have called 6 electricians. Out of that 4 looked at it and I actually have gotten quotes from 3.

A reality check is simple. Turn absolutely everything on in the house and the storefront (lights, ovens, stoves, air conditioners, every possible tool you currently own, etc.) and clamp a ammeter over each of the hot lines between the meter and the breaker box. Cut the main breaker, leave it off for a minute, then turn it back on. The ammeter will spike for an instant and settle down to the continuous draw with all the appliances running. The spike will be the "start up draw" when everything is powered on at once. The greater of the readings on each leg will be the readings you want to use. You will want to have someone used to working in a distribution panel do this for you. This "start up draw" is going to a fraction of what you were quoted by the electrician.

The electrician added up the amperage of all the appliances that could possibly be running at one time (while running at 100%load) and multiplied it by a 1.5x CYA (cover your ass) factor. (This is the exact same thing you will get from any HVAC sales guy quoting a new heating / AC system for your establishment.) I think you are missing an important difference between an electrician and an electrical engineer. I doubt another electrician will give you any more realistic results.

Using the electricians numbers (390 + 135 + 35 = 560). A 600 amp service will cover his calculations with TONS of room to spare! It will be cheaper to pay for 600amp service now and be covered than pay for 400 amp service now then pay for 600 amp later when you find out that 400 amp service is too small. What is the cost difference between 400 amp service and 600 amp service?

If it were me I would install a 400 amp service and never think about it again. If I were you I would install the 600 amp service and never worry about it again since you don't have any real comprehension of how huge 600 amps of 230v single phase is. 600 amps at 230v single phase is 138 kilowatts. I.e. 138,000 watts... 3,312,000 watt hours running full load for a single day.

$.11 per kwh x 138kw x 24hr = $364 to run full 600amp service for one day! (or $132,000 a year!). Of course you won't be running full load 24 x 365 but if you put it in terms you understand ($) you can start to see the absurdity of it all. 400 amp service will be more than enough to cover the highest load you will ever possibly actually see. 600 amp service is absurd but you will unquestionably have your butt covered. Anything higher than 600 amp service is just completely insane and the electric company will be laughing so hard that they will probably forget to put your order in by the time they stop laughing.

Have you priced out how much a 600 amp distribution panel costs? Have you priced out how much a 400 amp distribution panel cost? If you start to consider how much just the copper wire is going to cost to distribute 600 amps or 400 amps from the distribution panel to the wall receptacles where you are plugging everything in you had better be sitting down (AND have the paddles charged ready to go!).

P.S. How many actual home and shop square feet are you talking about? Are you talking about a 3000 sq foot house and a 3000 square foot shop? Or a 20,000 sq foot house and a 100,000 sq foot shop? How many sq feet is the retail space? I don't think in terms of mansions and factories so I could be totally off base here with a complete misunderstanding of the scale being discussed?

[Mitch schiffer]

Michael unfortunately the building is gutted right not so a actual amperage test is not a option. The total square footage is about 8k. If you have a couple tools that are pulling close to 100amps each before anything else is on it starts to seem like 400 amps or 320 nominal is not much especially when you start to introduce other medium size loads like the dust collection and air compressor or even items for the house we will have a steam generator for a steam shower l, 3 water heaters, 4 air conditioners, 3 ovens, 2 dryers, a snow melt system for a exterior patio, and probably a few more things im not thinking of. I know some of these could be gas, but with greatly increased gas prices im thinking I might stick with electric. I will say I am a bit numb to the size of services. I worked as a maintenance mechanic in a foundry where the service voltage was 13,600 volts at I believe 2000 amps. I could be over thinking it but I just want to do the best I can to balance budget with a product that will last me many years to come.

[derek labian]

I see Wisonson has many electric coops, so I'm not sure how helpful they would be. With the electric companies here (the 3 I know of in the area) all publish specs (which is where the electricians get the details of what and how to install) but you can also simply call them and open a ticket. They may connect you with an engineer who will actually come on-site to help asses your situation and provide advice.

If you have a couple tools that are pulling close to 100amps each

You may have already answered this and I may have forgotten, but is the 100a load on these machines from the load rating label, startup load, peak running load, or nominal running load? If you haven't tested, you may find that the nominal running load for these machines is substantially lower, and as long as they don't all start or reach peak load at the same time, you won't have an issue. Just a thought.

[Mitch schiffer]

You may have already answered this and I may have forgotten, but is the 100a load on these machines from the load rating label, startup load, peak running load, or nominal running load? If you haven't tested, you may find that the nominal running load for these machines is substantially lower, and as long as they don't all start or reach peak load at the same time, you won't have an issue. Just a thought.

1 of these is my wide belt sander which is currently in storage so I used a online calculator to determine the amperage of that if ran on single phase based on the nameplate amperage. From my understanding sanders can draw pretty close to full loads fairly easy. And the other is my wife's kiln so that is rated at the actual draw of the heating elements, however it wasn't clear to me how long that draw is sustained for. The other tools I just used the nameplate amperage for my calculations which didn't come out the same as the electrician. Im not sure how he came to his number. I have been meaning to test the actual amperage draw of all my tools but I haven't got around to it yet. I do trip 30 amp 2 pole breakers on a semi regular basis now with the air compressor and occasionally the shaper

[Lawrence Duckworth]

I built a 15,000 watt electric moly glass furnace that melts 200lbs of batch at 2350f, the furnace is single phase and draws about 60 amps when batching, at work/pipe temp i ramp down to 2100f, and draws maybe 32amps to keep. my annealers (2-7500watt, 1-5000 watt) work at 935f and soak at 780. and draw maye 25/30 amps at full bore which would be 1850f fusing temp. if your annealer actually draws 90 amps at annealing temp of 935f...that thing must be a monster and at nearly 22,000watts.... listen to Derek and Michael

[Mitch schiffer]

I could be overlooking something but the kiln she wants to get is rated by the manufacturer at 23,600 wattsScreenshot_20220204-104020_Chrome.jpg

[Lawrence Duckworth]

Wow 🤩 that’s a monster!!
Be interesting to see what she’s making 👍

[Tom M King]

This might be useful to someone figuring:
https://skutt.com/products-page/cera...627-3pk/#specs

That's a Nice kiln!

edited to add: That link doesn't take you directly to the specs page, but you can click on the link on that page. Looks like Cone 10 is only available with the 3 phase model.

[Mitch schiffer]

Tom thanks for that im not real firmiliar with kilns but I will ask my wife about this for sure. I got the watts from a different website after selecting the single phase model but it is possible that was incorrect or I misunderstood the description.

[Tom M King]

My Wife was doing pottery when we first met. After we got married, she wanted a pottery shop before we built a house. We decided to build the pottery shop back in the woods, and fix it so we could live there for a while. We've lived in it for almost 42 years now, but we have added onto it several times over those years. She stopped doing pottery after we had our first child, so the pottery business didn't last long.

[Timothy Thorpe Allen]

Another one chiming in with a wife who does pottery -- her big kiln (12 cubic feet) is gas fired, with an array of 6 burners totaling up to 150,000 BTU/hr (equivalent to 44 kw). She needs gas rather than electric in order to achieve a reducing atmosphere for the glazes she uses. A cone 10 firing takes about 10 hours and burns around 15 gallons of propane (and with one 120 size tank, we often suffer freeze-ups). She does have two electric kilns for the bisque firing (one at 32 amps, the other at 48 amps, both 240 volts single phase).

[Mitch schiffer]

Another one chiming in with a wife who does pottery -- her big kiln (12 cubic feet) is gas fired, with an array of 6 burners totaling up to 150,000 BTU/hr (equivalent to 44 kw). She needs gas rather than electric in order to achieve a reducing atmosphere for the glazes she uses. A cone 10 firing takes about 10 hours and burns around 15 gallons of propane (and with one 120 size tank, we often suffer freeze-ups). She does have two electric kilns for the bisque firing (one at 32 amps, the other at 48 amps, both 240 volts single phase).

My wife isn't into pottery actually. She does glass fusing but I believe the kilns are similar. I believe most glass kilns are electric due to better temperature control. I could be wrong on that though. I know we have a poetry kiln now that I got from a auction that needs a different controller before it can be used for glass. Do you know how sustained the draw is from your wife's electric kilns?

[Timothy Thorpe Allen]

I know we have a poetry kiln now that I got from a auction that needs a different controller before it can be used for glass. Do you know how sustained the draw is from your wife's electric kilns?

My wife's 32-amp kiln is controlled by manual switches and a cone-sitter. During a firing, she'll turn the switches on in succession during the ramp-up, until all elements are on and then it is running continuously at full draw until the cone-sitter turns the whole thing off. And I have clamped an ammeter on the leads just to satisfy my own curiosity! This is why a nominal 50-amp circuit requires that the wiring be sized for 60 amps because of the continuous nature of the load (check the installation instructions for the kiln you are interested in, they'll tell you what you need).

Cones, btw, in case you don't know, are a measure of heat work not just temperature. I believe the 48-amp kiln also has a cone-sitter manual controller -- we never hooked it up because it needs new elements and the smaller kiln has been getting the job done.

A modern computer controlled kiln might be a little different, but still it takes a lot of power to maintain cone 10 temperatures -- these kilns are not that well insulated!