Running 220v/100a to my Detached Garage/Future Shop - Page 2 - Woodworking Talk - Woodworkers Forum
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post #21 of 82 Old 09-27-2018, 07:39 AM
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Quote:
Originally Posted by NoThankyou View Post
Long story /short version

When an addition was added to the house a 100 Amp sub-panel was added to the shop, er garage. All shop wiring is via conduit. While running power to the various tools I noticed that the ground (green) and neutral (white) bus bars were not connected in the sub panel. Odd I thought and a simple fix.

WRONG

As soon as I connected the cable to the TV in the garage we started getting occasional pixelation on all the TVs along with other annoyances. It took me awhile to realize that the cable is basically an analog device and the extra wire in the sub-panel was creating a ground loop. Removing the extra jumper solved the problem.

There are some anal retentive inspectors that will require the jumper in the sub-panel. Pit it in to make them happy. Just remove it before you put cable TV in the shop.
In a sub-panel you keep the ground and neutral bars separated. All of the white wires go to one bar which is connected to a wire which goes to the main box. Then all the ground wires are connected to the other bar which the green wire goes back to the main box. There should also be a bare wire which goes outside to a ground rod driven into the ground. If that wasn't done the electrical work wasn't up to code and could be the reason for your TV problems.

The reason you separate the green and white wires at the sub-panel is the neutral wire is considered a current carrying line. The green wire is a safety only thing. It's connected to the body of a appliance or tool so in the event of a short the body of a tool isn't energized. Electricity would much rather pass through a copper wire to ground than you so it's there to protect you. If the wires were mixed at the sub-panel and for some reason the neutral wire became disconnected at the main box then the ground wire would then become the neutral wire and then the body of every tool would become current carrying just like the white wire.
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post #22 of 82 Old 09-27-2018, 08:05 AM
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We had a house built in Shreveport, LA. I noticed the ground and common wires were both on the common bar. The builder said it was acceptable. Then why do they have a separate ground bar and common bar in any panel??????

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post #23 of 82 Old 09-27-2018, 08:50 AM
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We had a house built in Shreveport, LA. I noticed the ground and common wires were both on the common bar. The builder said it was acceptable. Then why do they have a separate ground bar and common bar in any panel??????
If the box is used as a main breaker panel it is acceptable to mix the ground and neutral wires on a bar. If it is a sub-panel they should be separated. Some boxes are made with two bars so they could be used for either application. A lot of boxes only have one bar and you would have to add another bar to use it for a sub-panel.
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post #24 of 82 Old 09-27-2018, 09:04 AM
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Quote:
Originally Posted by Pineknot_86 View Post
We had a house built in Shreveport, LA. I noticed the ground and common wires were both on the common bar. The builder said it was acceptable. Then why do they have a separate ground bar and common bar in any panel??????

Most panels do not come with separate bars, you have to add the ground bar, and remove a bonding screw from the neutral bar for use as a sub panel. If the sub panel is in the same building as the main, no ground electrode is required. In a detached structure, the ground electrode is required. The main panel ( or meter base, in some cases) is the only place where the neutral, the EGC and the ground electrode are all tied together.

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post #25 of 82 Old 09-27-2018, 01:15 PM
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This was a main breaker panel in the house in Shreveport. I worked in R&D for an appliance manufacturer just after the earth cooled. Some of the connector blocks on a range had three screws and the new pigtail had four wires. A fellow in the engineering department worked part-time as a technician at a local radio station. He showed me that you could combine the common (white) wire and the green ground wire on the same terminal.

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post #26 of 82 Old 09-27-2018, 02:33 PM
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Originally Posted by woodnthings View Post
It is a "convenience" to not have to swap cords and plugs in the middle of an operation.
why swap plugs and cords? just plug everything in. nothing draws a load until it is turned on
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post #27 of 82 Old 09-27-2018, 02:43 PM
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as mentioned ground and neutral buses can be combined in a panel, separated in a sub-panel
many jurisdictions require separate buses in a panel with a main jumper between the two. this is more for the inspectors convenience in megging the panel, he'd rather remove a jumper than 20 ground screws. as you can see by my other post... i hate those under paid civil servant wanna be electricians that never had the skill set or smarts to actually get an electrical license inspectors :)
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post #28 of 82 Old 09-27-2018, 02:51 PM
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Originally Posted by GeorgeC View Post
Very true. However, I would not use that as an argument against putting in a 100 amp circuit. I would always go with the most capacity that was practicable/affordable.


George
i was just suggesting the 60 amp service run in the existing conduit would save the op from tearing up his asphalt driveway. he could always dig up the driveway to upgrade to 100 amps. practicable/affordable
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post #29 of 82 Old 09-27-2018, 05:27 PM
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You may riun out of slots in a 60 AMP sub

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Originally Posted by _Ogre View Post
why swap plugs and cords? just plug everything in. nothing draws a load until it is turned on

That's my point, go for a 100 AMP if possible. Mine is full. I have a lot of tools and machines and outlets and lights. They are all plugged in. The meter don't spin unless I turn something on. I get that. I still have to swap out my 3 HP planer my 3 HP resaw bandsaw occasionally because there is not an extra 240 V outlet on that wall. 240 breakers take up 2 slots, so you can run out of slots easily IF you have a bunch of 240 V machines like I have. Then you have to swap plugs.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #30 of 82 Old 09-27-2018, 05:37 PM
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Originally Posted by woodnthings View Post

That's my point, go for a 100 AMP if possible. Mine is full. I have a lot of tools and machines and outlets and lights. They are all plugged in. The meter don't spin unless I turn something on. I get that. I still have to swap out my 3 HP planer my 3 HP resaw bandsaw occasionally because there is not an extra 240 V outlet on that wall. 240 breakers take up 2 slots, so you can run out of slots easily IF you have a bunch of 240 V machines like I have. Then you have to swap plugs.

That's when you remove your one 240 volt outlet and install a small sub panel in place of it, then install two 240 volt outlets right next to the sub panel.

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post #31 of 82 Old 09-27-2018, 06:34 PM
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that won't happen

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That's when you remove your one 240 volt outlet and install a small sub panel in place of it, then install two 240 volt outlets right next to the sub panel.
I have 5 - 100 AMP subs in the residence, a 225 AMP main and a 175 AMP main which comprises a living area, 2 shops and a garage. I don't mind switching a plug now and then and that only happens in the wood shop. The house was originally wired for electric heat and in Michigan that proved to be way too expensive. I still heat with electric heaters in the shop and garage, but even that gets costly. The house was designed as solar heated with hot air panels and a heat storage unit but none of that ever happened. The sun don't shine all that much here during winter.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #32 of 82 Old 09-27-2018, 09:33 PM
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Originally Posted by TimPa View Post
neutral and earth ground are tied at one location in a residential service, in the MAIN panel only, and should be electrically isolated from there on out. subpanels included - not connected - ever. very surprised that an inspector made you install a jumper!!!!
Not all building inspectors are rocket scientists. The guy next door who is a building inspector says that he will advise against it but not reject it if the extra jumper is in place.

In another life I can remember three weeks of grief over three shifts where were looking for the logic/AC Safety ground short (about 22K Ohms) in a system. (Can not remember the end customer.) Finally we discovered is was the neutral of a transformer to the step down side. It was a nightmare! Faulty transformer.

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post #33 of 82 Old 09-27-2018, 11:07 PM
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Quote:
Originally Posted by NoThankyou View Post
Not all building inspectors are rocket scientists. The guy next door who is a building inspector says that he will advise against it but not reject it if the extra jumper is in place.

In another life I can remember three weeks of grief over three shifts where were looking for the logic/AC Safety ground short (about 22K Ohms) in a system. (Can not remember the end customer.) Finally we discovered is was the neutral of a transformer to the step down side. It was a nightmare! Faulty transformer.
All we can do is advise you what is common on building codes. Personally I can't picture a building inspector approving it. That is something that isn't borderline bad.
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post #34 of 82 Old 09-28-2018, 08:33 AM
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Locally the building inspector and electrical inspector are two different people. Same with plumbing inspection.

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post #35 of 82 Old 09-28-2018, 04:09 PM
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Quote:
Originally Posted by woodnthings View Post

That's my point, go for a 100 AMP if possible. Mine is full. I have a lot of tools and machines and outlets and lights. They are all plugged in. The meter don't spin unless I turn something on. I get that. I still have to swap out my 3 HP planer my 3 HP resaw bandsaw occasionally because there is not an extra 240 V outlet on that wall. 240 breakers take up 2 slots, so you can run out of slots easily IF you have a bunch of 240 V machines like I have. Then you have to swap plugs.
now i understand. your panel is too small, not the service. breaker spaces have nothing do with the size of the panel. you can have a 8 space panel with a 200 amp service (very common in trailer parks), or a 40 breaker panel with a 60 amp service (very uncommon anywhere). the amount of breakers has nothing to do with the size service or load. breakers protect the wire, nothing else. a 60 amp breaker feeding a sub-panel is sized at 60 amps to protect the wire going to the panel. each individual breaker is sized to protect the wire going to the branch circuit.

most residential circuits have minimal load on them, other than the kitchen and gfic circuits, code says nothing about the number of breakers for the rest of the house. you could run all the lighting and receptacles on one breaker. it would be stupid to do it; but code is minimum, not the recommended.

my shop had an existing 30 amp, 240 volt, 6 screw in fuse panel. when i wired my shop i bought a 20 breaker panel and threw in a 30 amp main. it's been that way for 20 years, have yet to pop either main. never mind the voltage drop, it's wired with 200 feet of 50 year old #10/2 uf cable.
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post #36 of 82 Old 09-28-2018, 04:16 PM
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@RepairmanJack
if you try the 60 amp service in the existing conduit... use a 20 breaker panel minimum, it will probably have a 100 amp main, replace it with a 60 amp main or not, the wire will be protected by the 60 amp breaker in the house
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post #37 of 82 Old 09-28-2018, 07:47 PM
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Originally Posted by woodnthings View Post
I still have to swap out my 3 HP planer my 3 HP resaw bandsaw occasionally because there is not an extra 240 V outlet on that wall.
just like multiple 120 outlets on a wall in the same circuit, you can add a 2nd or 3rd 240 volt plug to the circuit. if there's not enough room in the box to make up the wires along with the plug, just add a junction box and split the wires to each 240 outlet. i've done it many times. if the breaker is sized correctly for the wire, you can't overload the wire.

both your 3 hp motors should run at 17 amps on 240 volts. a simple 20 amp breaker and 12 gauge wire would work for that circuit. start up amps might be as high as 25 or more amps, but only momentarily and the breaker should handle it. if you have a 30 amp breaker and 10 gauge wire, you could probably run both machines as 17 amps is full load, idle amps may be as low as 5
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post #38 of 82 Old 09-28-2018, 08:03 PM
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Originally Posted by _Ogre View Post
just like multiple 120 outlets on a wall in the same circuit, you can add a 2nd or 3rd 240 volt plug to the circuit. if there's not enough room in the box to make up the wires along with the plug, just add a junction box and split the wires to each 240 outlet. i've done it many times. if the breaker is sized correctly for the wire, you can't overload the wire.

both your 3 hp motors should run at 17 amps on 240 volts. a simple 20 amp breaker and 12 gauge wire would work for that circuit. start up amps might be as high as 25 or more amps, but only momentarily and the breaker should handle it. if you have a 30 amp breaker and 10 gauge wire, you could probably run both machines as 17 amps is full load, idle amps may be as low as 5

To the best of my recollection, only one receptacle is allowed on a 240 volt circuit. Don't have the NEC book handy, if not so, someone will chime in.

Alexis de Tocqueville was a very smart man.
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post #39 of 82 Old 09-28-2018, 08:19 PM
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Originally Posted by Alchymist View Post
To the best of my recollection, only one receptacle is allowed on a 240 volt circuit. Don't have the NEC book handy, if not so, someone will chime in.
You are right however I think working by yourself if you know you are only going to run one piece of equipment at a time I would be inclined to break that rule.
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post #40 of 82 Old 09-29-2018, 10:22 AM
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If you decide to forget about the electrical code send any money you would have paid for fire insurance to charity, they will put it to good use, otherwise it is just wasted money.

“Everything we hear is an opinion, not a fact. Everything we see is a perspective, not the truth.”
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