Trouble getting service to the shop

[Bert_]

I always consider voltage drop. But here there is no hard limit. Many loads could care less about a little voltage drop and most common loads aren't any where near maxing out a circuit.

Voltage drop is a design issue. Kind of like how many circuits should you put in a shop. The code does not and should not cover these issues. That is left to whoever is designing the feeders and circuits, could be an engineer or as simple as the electrician and homeowner.

 

[ard]

Back to the OPs issue if we could?

Im not sure what is going on, but we have seen guys that are pretty clueless about electric and services get absolutely ABUSED by inspectors, county permit people and POCOs ..for all kinds of reasons.

POCO is too lazy to do work. Local county guy wants to show off and be abusive. Just to be a ****, for no good reason other than it makes them feel powerful.... Or more benign...they are idiots and dont know what they are doing, but because the owner also doesnt know, they sound like genius experts....

Very frustrating to those of us that have done this before.

Really hard to give good advice, becuase it is so hard to really understand what is going on - at the site; at that county; during any one conversation.

I feel bad for the OP- instead of focussing on his one issue and wht might be happening with his job, he is bombarded with tangents and 'heres what happened with my shop' posts. (Im not blaming anyone, we are trying to help)...but it can be hard for a noob to extrapolate that to his situation.

Anyway, good convo on VD and code. But hope the OP gets to the bottom of his poco and county guy jerking him around...

 

[wyliesdiesels]

Damaged equipment and wiring from heat generated by drawing inrush currents for longer than they're designed for. Causes voltage sag on the affected system for other equipment; potential for nuisance tripping and damage. The inverse time-delay action of circuit breakers can expose equipment to moderate overcurrents until the thermal action kicks in. Problems are compounded if the loads are cycling i.e. frequent on/off.

In-rush current draw time would not increase substantially(in-rush current occurs in 100s of a millisecond) due to voltage drop. This isnt a safety concern as the wire does not experience over-current long enough to heat up anyways.

In-rush currents are already over the ampacity of the wire to begin with.

Ive metered many loads with my Fluke 381 that has special circuitry for measuring in-rush current.

My 3 ton air conditioner pulls 85a on startup over #10 wire. Wire is sized correctly per nameplate.

Nuisance tripping occurs even when there is no voltage drop due to improperly sized breakers. This is not a safety issue either otherwise we would hear about it on a large scale. Monthly there are threads on here about nuisance tripping. And yet no safety problems resulted.

the thermal overloads on motors are sized for the current at rated voltage. So they would trip if the current got above that due to voltage drop. Again, this is a non-issue.

Ive seen this happen before. It didnt cause a safety issue.

All of your examples here do not hold water.

Voltage drop is a safety concern in other jurisdictions. I easily found 3 regulatory documents that set a limit. Engineers often supercede Code requirements anyway. Many smaller jobs do not involve an architect or engineer. Is 3% simply a rough rule-of-thumb for the USA?

3% is for feeders, 5% is for branch circuits.

If this was such a serious issue as you claim, the NEC wouldve addressed it long ago.

But its not, so youre grasping at straws....

 

[Railman67]

I really appreciate everyone that has offered insight into my situation. I know without seeing things first hand it's difficult to do so. The general opinion here seems to be that 100 amps will be adequate to run my shop. An electrician should be able to accomplish that for less than 10k. I hope. The local government here is a pain to work with, but with only needing 100 instead of 200 amps they should be easier to get around.

 

[checkthisout]

I really appreciate everyone that has offered insight into my situation. I know without seeing things first hand it's difficult to do so. The general opinion here seems to be that 100 amps will be adequate to run my shop. An electrician should be able to accomplish that for less than 10k. I hope. The local government here is a pain to work with, but with only needing 100 instead of 200 amps they should be easier to get around.

What if you dug trenches and set the conduit and panels yourself along with getting drywall removed and ready?

Is that within the scope of your abilities or a friend that you can pay?

 

[u2slow]

I apologize for the sidebar. I'll re-quote my 2 cents for the OP

So the 200' per the OP's shop....

#2AL @ 90amps = 3.7% voltage drop
#1/0 @ 90a = 2.32%
#1/0 @ 100a = 2.58%
#2/0 @ 90a = 1.84%
#2/0 @ 100a = 2.05%

Wylie - I suppose voltage drop considerations were beaten into me good and hard in electrical school in the early 2000's because it is regulated for us. (Canada and international maritime industry anyways.) Seems odd how prickly the NEC can be about some things, yet not specify a max voltage drop.

 

[Farmall450]

Might be worth calling your county supervisor to check this prohibition on an additional service isn't some **** the smartass inspector made up. Even if it is legit the inspectors boss needs to know that an attitude adjustment is required.

Agreed.

 

[ard]

but with only needing 100 instead of 200 amps they should be easier to get around.

Agree with the 100A assessment.

But don't understand how that changes them lying to you.... I suspect they are 'difficult' only because they know they can abuse you.

Good luck!

 

[jhelrey]

I'd be tempted to get a 120V 20A line ran, and run a generator for the times you need juice. No way would I pay $10,000.

 

[u2slow]

I think these big-shots are bored sometimes and latch onto the biggest amperage number discussed to make their work more interesting and profitable.

Last summer I got #2/0 ACWU for about ~$10/meter. Add a 100A shop panel for $100. Allow $100 for the shop breaker (100A) at the house. Some straps, connectors, misc.... Lets say ~$1000 in material. Labour, permit, digging all extra of course. Might be worth your while to do a homeowner permit.

Or just roll it out and hook it up. Pull the permit after you have the trench dug.

 

[SGKent]

I would still look at the zoning and see if that is affecting the outcome. If the zoning is residential or agricultural there may be a limit on the number of families who can use the property. Two meters may be looked at as two uses on the same property, and that would make it a mixed use property which requires mixed use zoning in many communities. If that is the rationale with the issue the first question would be, if the power company puts two meters on the property but agrees to one bill only will the county accept that. If no, then I would speak with the local supervisor(s) about getting a variance. Without knowing the zoning on this property it is hard to out guess the building dept. On the other hand if the real goal is to set up a small manufacturing business out back in a residential zoned area then the answer will always be no.

 

[850xpeps]

You guys can’t tell him he can pull 100 amps out of his 200 amp service without knowing the load calc on his house.

For instance my load calc on my house was 192 amps...... but I was including a 8kw boiler in the basement.

Also do you plan on heating the garage?

If your load calc allows the extra load to the garage then I would say go the route of a dual lug meter socket and a panel with a main breaker in the garage. The load calc for both panels can’t be over 200 amps.

When I was getting my quote for service done last year before building I knew I was building a shop in the future so opted for a 400 amp service and no extra cost only the prize of the underground wire which was $700 after $500 discount.

Cheaper to plan a head and I know your not in that spot because to go 400 now you need a different meter, transformer and blah blah blah.

 

[u2slow]

You guys can’t tell him he can pull 100 amps out of his 200 amp service without knowing the load calc on his house.

IMO, it doesn't really matter. Run a smaller breaker. Gets the shop going. The rest is details. Burying a big cable is smart because 200' of trench is the biggest part of the job. A future service upgrade will unlock any remaining potential.

 

[850xpeps]

IMO, it doesn't really matter. Run a smaller breaker. Gets the shop going. The rest is details. Burying a big cable is smart because 200' of trench is the biggest part of the job. A future service upgrade will unlock any remaining potential.

Yes burying a cable larger than needed for future kind of makes sense. But simple fact is if it’s too expensive to do it now.... it won’t be cheaper in the future. If he doesn’t have the required amperage available that’s what matters.

40x60 is a big shop. If it were me and the only way to get good power out there is to spend $10k. Then that’s what has to be done. The shop itself doesn’t need to be filling wired right away. That can be picked away at.

 

[Innovate1]

In-rush current draw time would not increase substantially(in-rush current occurs in 100s of a millisecond) due to voltage drop. This isnt a safety concern as the wire does not experience over-current long enough to heat up anyways.

If the voltage drop is enough motors won't ever come up to speed and pull inrush current until something opens the circuit. Ever try to run a table saw or some other equipment on too long or too small of extension cord? I have and that's exactly what happens.

Don't think it is a safety issue as thermal cutouts in the motor or breakers should trip but it does extend inrush current significantly and it's not a good situation.

 

[checkthisout]

I would put new service at the shop then run it back to the house.

Or,

Put a 380 amp meter base out in the yard with 2 200 amp switches with one feeding the shop and the other going to the house. You can unearth the existing line from the transformer to the house and plug that into the meter base.

Of course all this depends on where everything is on the site. Any chance you can draw a map or satellite photo of the property? That would make this thread way cooler.