BajaNomad - Question regarding electrical panel

Question regarding electrical panel

Santiago - 2-26-2011 at 04:00 PM

This used panel is going in my small off-grid cabin. I will run the hot from the inverter thru a 60am disconnect and to one of the hot buss bars.
1. Don't I run a wire to the other hot buss bar as if the black and red in the photo were tied together?
2. This panel has a small ground buss in the upper left hand corner; I can't remember if I'm supposed to tie that to the neutral buss (black arrows in the photo) or not and I get different info on the internets.
3. Came with two 20s and two 30s - aren't the 30s a little high for a small cabin - I was thinking of replacing them with 15s and using one of the 20s for the kitchen (all propane appliances). Are GFCI breakers the way to go or just use GFCI outlets in the kit/bath/exterior and run everything thru those?

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woody with a view - 2-26-2011 at 04:19 PM

sorry. all i know about electricity is it is invisible and it hurts....

so, do'nt stand in a puddle when you tie in your GFCI's on the wet circuit!

msteve1014 - 2-26-2011 at 05:28 PM

Hi Santiago,
Yes, tie the two busses together if you only have 120 vac to feed it with.
You do not need to bond the ground and the neutral busses together.
Yes, 30 amps is probably more than you need, you would be better protected with the smaller breakers, and most likely you will never trip one of them if you are being careful about your power usage because of being on solar.
If you are going to buy a new breaker any way, check the prices on gfi breakers verses a gfi plug. They will both do what you want.

p.s. buy a ground rod if you do not have one yet, and bond everything to it.

[Edited on 2-27-2011 by msteve1014]

Santiago - 2-26-2011 at 05:37 PM

Thanks Steve: I also just realized that having a disconnect between the inverter and the panel is not needed - don't I just shut the inverter off?
I was going to make a ufer out of a 20' piece of #3 rebar (only size I ever see in BOLA) buried about 2' deep for ground - is this OK for ground?

Bob and Susan - 2-26-2011 at 05:42 PM

the 60 amp breaker for the inverter is probably too big

most inverters are 33amp
so if you stacked 2 then the 60 amp would work

i'd run a 30 amp breaker on one

you can still run the 20 amp breakers

i would fill the box with breakers now...for use later
they are about 10 bucks each

do not connect the common and the ground
you could fry the inverter
remember the inverter is only circuit boards

edit...make sure you mark all the breakers
you will forget what's what later

[Edited on 2-27-2011 by Bob and Susan]

woody with a view - 2-26-2011 at 05:42 PM

deeper. on this side it's 5 feet deep. but that is 2010 code. prolly diferente in baja, where the draw is much less on the entire house.

msteve1014 - 2-26-2011 at 06:04 PM

With the power you will be using you could use one of your 30s as a main in the panel and forget the disco.
The ufer would be ok, but the deeper the better with the dry soil i'm sure you have. Drive a piece of re bar as far in as you can and tie on to that.

RnR - 2-26-2011 at 09:00 PM

Don't forget - the breaker size determines the downstream wire size. Or vice-versa, the wire size determines the maximum size breaker. The intent is to trip the breaker before the wire overheats and possibly arcs or starts a fire.

So, that said, 15 amp breakers require a minimum of 14 ga wire, 20 amp/12 gauge, 30 amp/10 gauge. Change those 30 amp breakers to something smaller or you will have to wire everything with 10 ga wire!

Ex: 14 gauge wire is rated to carry a maximum of 15 amps without overheating. A downstream appliance could short, pull 25 amps, overheat the 14 gauge wire, and never trip the 30 amp breaker.

BajaBruno - 2-27-2011 at 12:33 AM

Good advise here. RnR says it right on choosing breaker sizes--it all depends on the load, which determines the wire size, which determines the breaker size. But, nothing says you can't use 14g wire and a 15 amp breaker for a 5 amp load. However, if the load is much higher (not likely in your solar cabin), then choose the right wire size first.

A GFCI won't work without a good ground. Woody and msteve1014's advise is good--drive that rebar straight down 8' or so and you should be OK. You can do that by slipping a heavy piece of pipe (with cap on end) over the rebar and slamming it down. Outlet GFI's are much cheaper than breaker GFI's and will protect regular outlets downstream. Don't use them on appliances--motors don't like them and it is unnecessary.

Whether the ground and neutral buss bars are tied together depends on the installation: main panel, yes; sub-panel, no. You are using a sub-panel as a main panel, so I don't know, but it's probably a crap shoot.

RnR - 2-27-2011 at 06:58 AM

Quote:

Originally posted by BajaBruno

Whether the ground and neutral buss bars are tied together depends on the installation: main panel, yes; sub-panel, no. You are using a sub-panel as a main panel, so I don't know, but it's probably a crap shoot.

Tie them together.

According to the NEC (National Electrical Code), all "separately derived power sources" are required to be grounded as close to the service entrance (usually the main panel) as possible. The inverter is a "separately derived power source" equivalent to a power company's step down transformer on a distribution line. IE: The source of the 120/240V power.

Household systems are to be grounded "at only one point". Usually the main panel. If a sub was connected and bonded, the nuetral and ground wires will provide TWO return paths for the electricity from the sub to the main and current will actually be flowing in both the nuetral and ground wires between the sub and the main. That is why main panels are connected and subs are not.

There is no real distinction between a breaker box designation as a sub or a main. It's just a metal box. The distinction is in how it is used and wired. That's why there is a green bonding screw for use in the nuetral buss supplied with every new panel and a tag that says something to the effect that "use this screw when equipment is to be used as "service equipment".

RnR - 2-27-2011 at 07:03 AM

If anybody wants to know how and why a GFI works, just ask. It's a little complicated but interesting. They are not overload devices, (breakers).

1bobo - 2-27-2011 at 07:09 AM

Quote:

Originally posted by BajaBruno
Good advise here. RnR says it right on choosing breaker sizes--it all depends on the load, which determines the wire size, which determines the breaker size. But, nothing says you can't use 14g wire and a 15 amp breaker for a 5 amp load. However, if the load is much higher (not likely in your solar cabin), then choose the right wire size first.

A GFCI won't work without a good ground. Woody and msteve1014's advise is good--drive that rebar straight down 8' or so and you should be OK. You can do that by slipping a heavy piece of pipe (with cap on end) over the rebar and slamming it down. Outlet GFI's are much cheaper than breaker GFI's and will protect regular outlets downstream. Don't use them on appliances--motors don't like them and it is unnecessary.

Whether the ground and neutral buss bars are tied together depends on the installation: main panel, yes; sub-panel, no. You are using a sub-panel as a main panel, so I don't know, but it's probably a crap shoot.

Why do you say appliances don't like GFI's? Not questioning your expertise, but rather my assumptions.

cj5orion - 2-27-2011 at 08:05 AM

Quote:

Originally posted by Santiago
Thanks Steve: I also just realized that having a disconnect between the inverter and the panel is not needed - don't I just shut the inverter off?

Use the extra breaker for a main disconnect.
There are times.... when you'll use it.

Is this how I make one of the 30amps a disco?

Santiago - 2-27-2011 at 09:13 AM

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Believe it or not, I'm a general contractor but the only thing I know about 'lektrical is to hire a good electrician and then hope the inspector catches anything goofy. Of course, I DID have a cabin in Shaver Lake burn down following just this procedure.....

wessongroup - 2-27-2011 at 09:22 AM

Of course, I DID have a cabin in Shaver Lake burn down following just this procedure.....

Santiago ...... still laughing...

[Edited on 2-27-2011 by wessongroup]

Bob and Susan - 2-27-2011 at 09:37 AM

he question is...did you save "the box" :biggrin:

RnR - 2-27-2011 at 09:43 AM

Quote:

Originally posted by Santiago
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No reason that this won't work.

Some cautions:

1. Might want to cover the exposed lugs/buss of the "A" side with tape or shrink wrap. Turning off the 30 amp/disconnect breaker to the "B" side still leaves those "A" side terminals hot and exposed.

2. Putting breakers in those "A" side slots to cover them and then using those breakers in the future may lead to turning off the disconnect and again leaving the "A" side breakers and circuits hot.

3. Do the next future owner a favor and put a note/tag on the breaker explaining the setup.

BajaBruno - 2-27-2011 at 11:52 AM

Quote:

Originally posted by 1bobo

Quote:

Why do you say appliances don't like GFI's? Not questioning your expertise, but rather my assumptions.

GFCI's are designed to protect people, rather than wire, by tripping in the presence of even tiny amounts of current traveling to ground, such as might happen if you touched a broken wire while you were grounded.

Some appliances create these tiny ground faults, either deliberately (such as a stove ignitor) or unintentionally (in a motor). They are not a shock hazard in a well designed electrical system, but they will give you annoyance trips with a GFCI, which is why your refrigerator is not plugged into one, and your garage has a single non-GFCI outlet for these type of appliances.

Most appliance manufacturers recommend against using GFCI outlets for their products. I hope this helps.

msteve1014 - 2-27-2011 at 11:57 AM

Quote:

Originally posted by Santiago
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No, run the hot from the inverter to the 30 amp c.b. Tie the two hot buss lugs together, like we were going to do any way. Now both busses are fed by the 30, and all the other spaces are switched by the 30 amp "main".

[Edited on 2-27-2011 by msteve1014]

Bob and Susan - 2-27-2011 at 12:11 PM

why don't you get a better box with a place for a main cut-off

and then the breakers

cost about $30 usa at home depot includes breakers

Got it - final diagram and now we can start drinking

Santiago - 2-27-2011 at 12:48 PM

OK: black and white from inverter; green/yellow ties the ground and neutral busses; green to ufer ground and red ties the two hot busses together so they are both 110v. Throw the left 30 amp and everything to the right is disco. :cool:

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Bob - you're right, I'm just trying to use what I've got laying around in the shop until everyone who owes me money gets out of bankruptcy -- sheeesh.

Kinda funny how this got started: last spring SWMBO brings down a bunch of candles for lighting - OK, no problem. My fishing buddy and I go down in early October for a fishing trip and one evening I light all the candles, put on some latin jazz, pour a couple of glasses of WHITE wine and start making a pizza while my buddy opens a book. My neighbor comes over and remarks that it sure looks 'gay' in here.....5 minutes later we had both coleman lanterns on full blast, switched to blues/rock and Jack Daniels. Gotta nip these things in the bud.

[Edited on 2-27-2011 by Santiago]

Bob and Susan - 2-27-2011 at 01:16 PM

i still say don't tie the ground to the common

a common feed still has some electricty and could fry the inverter

you ARE NOT "on the grid"

Bob and Susan - 2-27-2011 at 01:17 PM

i have one panel like that but i bought a double breaker for the main breaker

then the hot from the inverter to that and loop it

then both top and bottom strings are protected

[Edited on 2-27-2011 by Bob and Susan]

msteve1014 - 2-27-2011 at 02:38 PM

Everything is protected by the 30 the way it is wired now, you do not need a 30 on each leg. Bob may be right about the bonding. There is no need to tie them together. The neutral can be left "floating". It is not a common practice, but some systems are wired that way to prevent "roaming" currents in sensitive electronic equipment.

wessongroup - 2-27-2011 at 02:56 PM

BajaGringo - 2-27-2011 at 03:10 PM

Quote:

Originally posted by Bob and Susan
i still say don't tie the ground to the common

a common feed still has some electricty and could fry the inverter

you ARE NOT "on the grid"

I am no electrician but folks who are (and I know) tell me the same thing - keep the common and ground separate in the panel when the power is fed from an inverter.

Might be a good idea to check with a an experienced, licensed professional you know and trust to be completely safe on this one.

(My attorney made me say that...)

[Edited on 2-27-2011 by BajaGringo]

captkw - 2-27-2011 at 04:27 PM

why do I see more funky wireing,the older I get?????

BajaBruno - 2-27-2011 at 05:38 PM

Quote:

Originally posted by Bob and Susan
i still say don't tie the ground to the common

a common feed still has some electricty and could fry the inverter

you ARE NOT "on the grid"

After a little research, I see that Bob/Susan is sometimes correct. Some inverters (e.g. the Sunpower model) have the following warnings:

"The inverter must be connected to an AC equipment-grounding conductor directly and a DC grounding electrode conductor to a single point ground.

"The AC Neutral connection is for voltage sensing only and is not used as a current carrying conductor, nor is it bonded to ground."

Others, however (e.g. SureSine model), require that both the AC and DC neutral and the AC grounding wire are bonded to earth at the same place. This is the type I am familiar with.

Having been humbled, it seems that, once again, reading the manual is the best place to start. What kind of inverter is it, Santiago?

Bob and Susan - 2-27-2011 at 06:15 PM

the "weakest link" and MOST expensive part is the inverter

protect that at all cost

it's like a lightbulb...it could go out at any time...then you're in trouble

Santiago - 2-27-2011 at 07:40 PM

I don't have the inverter yet - but I notice that Midnight Solar shows that their e-panel has the ground buss and the neutral buss connected. I have a pdf file of it but can't figure how to post a pdf file. Trace's gagillion page installation manual is no help what so ever.
I'm going with the guy with the dachshunds as I'm a doxie guy - and I suspect he's living with his decisions. The green/yellow goes.
Thanks a lot for the info and opinions - it has helped. Now where's that white wine....

Bob and Susan - 2-28-2011 at 06:01 AM

the work never ends...

biggerhose.jpg - 47kB

durrelllrobert - 2-28-2011 at 02:09 PM

if you total the wattage of all light, appliances and other stuff on each circuit and divide by 120 volts you get the total amps being drawn for that circuit. the main amperage is the total watts of all circuits. even though most of the lights and appliances wil not be on all the time there only needs to be one time for all to be on to exceed the allowed ampacity of th circuit .
US Code only allows any circuit to be loaded 80 % of its rated load. , and to be sure there is absolutely no fire hazard, the 80% rule should be followed.

A 15 amp circuit with 14 gage wire can only be loaded with a total of 1440 watts,which is 80% of the 1800 watt maximum.

A 20 amp circuit with 20 gage wire can be loaded 1920 watts which is 80% of the 2400 watt maximum.

Bob and Susan - 2-28-2011 at 03:25 PM

20 guage?

i'd put 6-10 guage

i guess no hairdryers if you use 15a breakers
some are 1500w

and then what about the times you need a toaster...
or
a breadmaker

bajalou - 2-28-2011 at 04:44 PM

Quote:

Originally posted by durrelllrobert
A 15 amp circuit with 14 gage wire can only be loaded with a total of 1440 watts,which is 80% of the 1800 watt maximum.

A 20 amp circuit with 20 gage wire can be loaded 1920 watts which is 80% of the 2400 watt maximum.

Smaller wire for larger load???? :?:

msteve1014 - 2-28-2011 at 05:10 PM

I think that was a topographical error. :lol:

20 amps= 12 gauge
Don't get all carried away with the calcs. If your on solar, you will probably be watching your amps and volts real close.

durrelllrobert - 2-28-2011 at 05:19 PM

Quote:

Originally posted by msteve1014
I think that was a topographical error. :lol:

20 amps= 12 gauge
Don't get all carried away with the calcs. If your on solar, you will probably be watching your amps and volts real close.

yep, typo. meant 12 gauge :rolleyes:

Bob and Susan - 2-28-2011 at 06:00 PM

heat is a BIG factor down here

in the summer when its HOT the wire heats up and you should use BIGGER wire

don't discount this factor...we ain't in kansas anymore