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  #1   IP: 67.253.184.77
Old November 21st, 2012, 09:52 AM
amp amp is offline
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Question 400 or 200 amp service

Hey folks..I've been a bit busy so I haven't checked-in in awhile. I'm just starting to gather information for this winter/spring job, but wanted to get some advice first. Customer has a plot of property in which a barn is almost completed. This is a really nice barn and one floor will be dedicated to a workshop. He's a big woodworker and has a lot of equipment. I'm in the process of talking with the electric company about what service they will allow. In the next year or so, the customer will be putting a house on the property as well and it will turn into his main residence. I'm guessing the power company will want two separate services for this property (one for the barn, now....and one for the house later). I was told an engineer will come to the property and give options in addition to cost, advantages, dissadvantage, etc. If I want to get ahead of this a bit so I'm the most informed when the power company comes out, do I just do a load calculation based on all of his equipment and determine if I need a 400-amp or 200-amp....assuming these will be separated services for the barn and house? When do you hit that line of saying you need more than a 200-amp service. This will be easy enough to perform....I just haven't had a customer do it in this order! Thanks for the advice!
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  #2   IP: 130.76.32.212
Old November 21st, 2012, 02:55 PM
suemarkp suemarkp is offline
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It would be cheaper for the customer to have one large service instead of two separate ones. Each service will have a meter, and there is usually a $10 to $15 per month meter fee, even if you use no electricity.

So first, I'd add together the anticipated loads of both buildings (do one service calculation as if all equipment was in one building). Also consider how many men are going to work in the shop. If just a one or 2 man operation, what is the worst case simultaneous use of equipment (e.g. dust collector + saw + lights, or dust collector + air compressor + lights, or welder + ??). Then, do two separate service calculations, one for each building.

The first calculation tells you how large the service needs to be and what you tell the POCO you need. The other two tell you how large the feeder to each building needs to be. The sum of the building feeders will be larger than the first calculation.

Typical ways of doing this:
1. Put a 400A meter on a pole and run two sets of service conductors from it -- one to the house (future) and one to the barn. Most places do not require a disconnect at the pole, but some do. That will add costs and require 4 wires from the pole to each building.

2. Put a 400A meter on the barn with a 200A disconnect for the barn and provisions for a 200A service to the house. The barn should not require a disconnect for the house, but some places may require it. So again, possible added costs.

3. If the house can get away with a 125A service or less, then put your service (200A or 400A) at the barn and run a 125A feeder from the barn to the house when you're ready. This will require a 4 wire feed and come from a 125A breaker in the barn panel. Make sure you get a panel that offers a 125A double pole breaker (some only go up to 100A) and has the bending space to support wires that large (will probably have to be copper).

4. Find a 200A panel with feed through lugs or use a 200A subfeed lug kit if the vendor makes one to feed a full 200A to the house (install the panel at the barn). These plug on like a breaker, but angle the wires up or down and have no overcurrent protection. This would allow you to implement a 200A feeder to the house, but you'd have to minimize the other breakers in this 200A panel and the house load and other circuits in the panel will be limited to 200A.

If you need a service larger than 200A, it will be cheaper to use two smaller panels instead of a single 400A panel. Most people use dual panels, even if they only need 250A or 300A or 400A.

Also, think about generators. If they ever want to run things from a generator, this also gets complicated since 400A services are split between 2 panels. Need to decide which panel doesn't get the generator and think about that design now.
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Last edited by suemarkp : November 26th, 2012 at 09:22 PM.
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  #3   IP: 173.29.96.157
Old November 26th, 2012, 08:13 PM
Nexis Nexis is offline
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Another thing to keep in mind when doing this. Is the woodworking for a business or is this a hobby. If its a business it may be advantageous to run 2 meters so you can keep the bills separate.
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  #4   IP: 198.208.159.20
Old November 30th, 2012, 07:54 AM
amp amp is offline
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More than likely it will be a business, so the idea of isolating the serivces was a thought brought up by the customer. I think he's ok with a monthly meter fee. BTW, I'm going to take suemarkp's advice and do a total and a individual load calculation based on all the maximum amp draws of all the equipment that will be operated. When I complete that, how do you determine if 200 is good enough? I know this sounds like a 101 question, but do you perform a 'worse case' situation when most everything could be running at the same time? And say if you're with 20% of a 200-amp draw.....then you should upgrade to a 400-amp service? Just curious on how to determine it. Most all of the houses I upgrade are turn of the century and have pretty typical modern day requirements.....as a result a 200-amp service is perfect (with some room to expand). This is a bit different for me, so curious on the critera to make a decision. Thanks!
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  #5   IP: 130.76.32.50
Old November 30th, 2012, 11:26 AM
suemarkp suemarkp is offline
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If it is a business, then he'll probably be required to have a separate service. A key question to ask -- are any of his tools 3 phase or will he want to buy any 3 phase equipment. If so, then query as to whether it is 208, 240 or 480V 3 phase. Hopefully if he wants 3 phase he can live with 208V. Also, does he plan to add machines later or does he have all the nameplate information now for what you'll be providing circuits for?

With this 2 meter approach, you do a service calc for just the barn and a separate one for the house because one will not affect the other.

If the demand load calculation for the barn comes to 200A or less, then you may put in a 200A service. The real question is what approach do you take to the service calc -- a worst case all loads running, or a degraded one assuming a work force of a given number. That is the only choice you have unless this is an existing shop and you have demand metering for 30 days or more to establish the load.

It would be nice if the NEC had some demand factors for workshops, but they don't. So either you have to assume all equipment is being used at one, or tell the inspector that the shop was designed to accommodate X number of people and the worst case loading you'll get is Y. Because this is a workshop and not a dwelling, you have to do the Standard calculation and your lighting load may be considered continuous. Realize that the lighting load won't be 3VA per square foot, but whatever the table has for a workshop (and not sure a workshop is in the table).
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  #6   IP: 198.208.251.23
Old December 3rd, 2012, 06:36 AM
amp amp is offline
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I'll ask what he has in terms of 3-phase equipment. I know there are a few pieces of equipment that are 3phase, but the majority is not. I'll inquire about if they are 208, 240, or 480V as well. If there are only a limited few pieces of 3-phase equipment...can you use some type of convertor? Must be more cost effective than trying to run 3-phase to a site (if it was even available). We should be talking today about his requirements more specifically so I'll start with what you mentioned in the post. Thanks.

Last edited by amp : December 3rd, 2012 at 07:28 AM.
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  #7   IP: 130.76.32.52
Old December 3rd, 2012, 10:06 AM
suemarkp suemarkp is offline
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There are phase converters available to run 3 phase equipment from single phase. But they can draw a lot of power. If he's buying tools meant for commercial shops, the 3 phase stuff if pretty common.

It would be better to provide a 3 phase supply if he has any 3 phase equipment of 6HP or more. But those panels cost more, the service and meter fee may be higher, and he has to watch the supply voltage (208 -vs- 240). Most homeowner grade tools (even the higher end "professional" ones) expect 240V single phase. Those could be a problem when run from 208V unless you use a buck boost transformer, and some motors will take either voltage.

The customer should really draw a line in the sand with which family of tools he wants. 240/120V 3 phase (high leg delta) is less common in many areas compared to 208/120, but if the 3 phase tools are 240V delta that is a good solution. The 208/240V split is the line he needs to draw.
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  #8   IP: 67.253.184.77
Old August 6th, 2014, 07:30 PM
amp amp is offline
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Question Layout for running 230V equipment

I had a few follow up questions.....curious on how folks would approach this. The service in the barn is a 200-amp service, 40-circuit, 40-space.
Most of the equip is labeled 230V with a start-up current as well. I don't have a current list of the equipment, but I have a real good ballpark to at least determine a good approach. Note: The panel is on the opposite end of the barn that the equipment is. Also, I'm approximating 8 spaces of the 40 are used. Another 4 will be used for dedicated 120V circuits. This leaves 28 spaces or (14) 230V dedicated circuits. Customer probably has 14 or more 230 or 240V pieces of equipment such as:
jointer - 230V / 9amp
panel sander - 230V / 8a
table saw - 230V / 7a
This just a small snapshot, but you get the idea (good average usage).
1. Being that this is mainly a 1-man shop (2 tops), is there a way to run more than one piece of equipment on a circuit? Do all the 230V circuits need to be dedicated?
2. For the jointer above, 230V / 9amps.....I'm pulling 4.5amps from each 120 leg in the panel, right? Would you use 12-3 on this? Each hot wire is more than capable of carrying 4.5 amps and the return and ground can handle the combined amperage as well. This plays into my first question. Am I thinking about this right?
3. Again since this basically a 1-man shop with a lot of equipment, does it almost make more sense to run a few subs closer to the equipment if combining equipment on a circuit is not an option? That way, there might be a few more spaces in a sub for additional 120V lines or even another 115/230 line.
Thanks as always!
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  #9   IP: 76.121.216.211
Old August 6th, 2014, 08:14 PM
suemarkp suemarkp is offline
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No, not all 240V circuits need to be dedicated. If you have two motor driven tools, and each draws less than 9 amps, you could put both on the same circuit and use them at the same time. The calculation rule is the sum of motors plus 25% of the largest motor can not exceed the circuit rating (most likely 20A). A picky inspector could get you in to trouble if he makes you use the motor table for the amp value (it goes by horsepower). Many tools lie on HP rating, and most don't draw the motor nameplate amps unless the tool is under load. So doing it completely by the book requires a bunch more circuits.

No, you're not thinking about this right. A 9A 240V jointer is pulling 9A from each leg (it is going out of one leg and in to the other). This is just like a 120V circuit where a 9 amp tool is pulling 9A from the hot conductor and returning 9A on the neutral. Most tools only need two hots and no neutral. But, you should look at the power plug as some tools have built in 120V light sockets so those would have a 4 prong plug. If you don't know what he'll have, you may want to run 12-3 just so you could mix in a 120V receptacle should one be needed or you get a tool that needs a neutral.

I'd assess what he has and try to determine what could possibly run at the same time. I'd put a dust collector on a different circuit than one with the dust making tools. If there are other things that are small and can run at the same time and fit on the circuit, those could go on the dust collector circuit too. I'd also put an air compressor on its own circuit since they tend to be hard users (but short duration). He probably can't use the jointer, table saw, sander, drill press, etc at the same time, so all those could share a circuit.

The main fly in the ointment is power plugs. Hopefully, they all have 15A or 20A 240V plugs (most 240V 20A plugs are T slotted like the 120V ones so they will take a 15A or 20A cord). A twist lock plug is OK too, but adds work for you if he has a mix of stuff and wants to move them around. A 15A twist lock won't fit into a 20A twist lock receptacle though. If something has a 30A, it needs to be on a 30A circuit. Definitely don't put multiple 30A plug equipment on the same circuit unless you know he'll never run two at the same time. It shouldn't have a plug that large unless it has a motor of 16A or larger.

Some shops try to plug all their equipment the same (e.g. 30A plug on everything) so only one outlet type needs to be installed. This can be permissible with motors, especially if they have a large breaker to ride it through start up. The rules that let you put a #14 wire on a 12A motor using a 30A circuit breaker can not be used when cord and plug connection is used. The motor in that case would have to be hard wired or cord-and-plug on a #10 30A circuit.
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Last edited by suemarkp : August 6th, 2014 at 08:27 PM.
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  #10   IP: 161.242.10.254
Old August 14th, 2014, 08:02 AM
amp amp is offline
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Quote:
No, you're not thinking about this right. A 9A 240V jointer is pulling 9A from each leg (it is going out of one leg and in to the other). This is just like a 120V circuit where a 9 amp tool is pulling 9A from the hot conductor and returning 9A on the neutral. Most tools only need two hots and no neutral. But, you should look at the power plug as some tools have built in 120V light sockets so those would have a 4 prong plug. If you don't know what he'll have, you may want to run 12-3 just so you could mix in a 120V receptacle should one be needed or you get a tool that needs a neutral.
Just so I'm understanding this perfectly......the way you describe it sounds like there's 2x the pressure (voltage) in the line when describing 240V vs 120V. Each hot leg is 180 deg out of phase....so each leg serve's as the others neutral path...and that reverses every 60x/sec. So, why do some boilerplates say 240V/9a, 120V/4.5a? At first glance it looks like if you run the circuit 240V you will use 9amps....and 120V you will use 4.5a. Thinking about this, it must be that there is some type of 120V circuit that requires 4.5a.....requiring an additional conductor. So 12-3 instead of 12-2. do you add the 9a and 4.5a together?
I'm starting to think about my dryer and why it is 4 conductors and it makes sense. I understand there is a 120V circuit to run the timer....but the timer is running as the dryer is running as well. I guess the 120 V circuit has it's own neutral so do you not add this current together when sizing a circuit? meanwhile I have the 240V part of the circuit functioning as I mentioned above when the dryer is on as well.

Last edited by joed : August 14th, 2014 at 08:23 AM. Reason: fix quote
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