sharing emt with a battery back up

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Jim W in Tampa

Jim W in Tampa

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Tampa Florida
Am in process of remodeling my master bed room.It is being built to withstand a cat 5 hurricane.I am rewiring it in emt mostly for flexability to change as needed.We would like to have a quad at each location,one duplex on normal #12 20 amp arc fault,and other to be for small battery back up 1800 watt with batteries that can hold up for about 10 hours at half load if needed.My question is can they share the same conduit ?
 
Re: sharing emt with a battery back up

Jim W in Tampa said:
...and other to be for small battery back up 1800 watt with batteries that can hold up for about 10 hours at half load if needed.My question is can they share the same conduit ?
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With the way you describe your application it does not fit the Scope definition of Article 700 "Emergency Systems", if it did the answer to your question would be no, as per 700-9(B).

Your described application does fit the criteria of Article 692 "Fuel Cell Systems" and it sounds like a stand-alone system. See 692-10 & 692-31 these allow your circuits to be installed "normal" (as per Chapter 3) and not separate like in 700.

Yes your wiring for branch general lighting and battery back up can share the same conduit because you are not installing an emergency system.
 
Its purpose is to keep lights,tv,radio,computer and my security cameras running while a hurricane is going thru in the likely event of loosing electric.There is a generator back up but would require rope pull to start it.This back up itself is supplied by the same bedroom circuit.
 
Optional Standby Systems

Optional Standby Systems

Yes is the correct answer. Article 702 . Optional Standby Systems. Make sure all wire insulation is rated for your highest voltage.
 
702-2 & 702-9 "The optional standby system wiring shall be permitted to occupy the same raceways, cables, boxes, and cabinets with other general wiring."

Yes install it :)
 
Thanks,i felt it was plenty safe but wanted other opinions.All of the wires will be thhn and will include a green ground wire as well as other conductors.Emt just seems like best way should changes ever need be made.Florida is exspected to have a hard next 10 years so its worth prepairing.
 
What type construction

What type construction

Jim, would you comment on what type of construction/studs etc. your employing on your project. I've been a master electrician/electrical contractor for 28 years with residential, commercial, industrial, hospital and institutional experience AND I never/remember anyway, wiring a residential bedroom with emt.

From working in commercial and or hospitals etc, its hard enough fighting emt thru steel studs already punched and having to punch extra holes thru plates to boot with a stud puncher. You might have radius issues around corners and all the rest of it. I cant imagine boring/notching holes in wood for this application. Sounds like grief. Beware of the Building Inspector. I suppose you could "stub out" into a drop ceiling/attic, or stub down into the basement, it might work, but boring/notching wood and installing emt is not how I would go. Maybe ent, ac, mc etc. I would be careful of radius with ent. Please explain. Tell me your using 6" steel commercial type stud construction. :D
 
I gotta jump in with Gmack here, you can weaken your structure for the sake of what?s thought of as a "better application", and you will certainly spend more money for conduit circuitry.

I often use a question to help agencies and designers decide if they really want to spend more money for a conduit application and it is: when was the last time you, your staff, or a contractor added circuitry through existing conduit to a particular destination for an item? Usually they cannot answer this question and I know myself in the 28 years I?ve installed I can probably only count on one hand when I have. I can also couple this with two prices one for cabling and the other for conduit and the value difference usually resolves the issue because most of the time it's about a 60% savings to cable.

Honestly an electrician will most likely prefer to install new rather then fish through existing because there are so many unknowns involved like, potential damage to existing wiring, wire fill, chasing through multiple outlets to the destination, splicing, opening and closing multiple outlets, overload, derate, power off ? Whew, I?ll just bring another new one in.

In residential, with correctly sized circuitry, I believe the best application is NM cable and not just for cost it?s simply fine for the application.
 
While i am not the best pipe bender going around corners is not tough .Reasoning behind the emt is that i have 500 hundred feet in storage and plenty of wire.Also have enough romex and plastic boxs to wire a large house.Material is not a factor here.After all the wiring is in and extra hurricane straps added it will then be geting 2 layers of plywood .Liquid nails goes on studs first and between layers of plywood.Drywall will then be added.Overboard ? Maybe ,but then piece of mind that my family has one safe room to run to is worth the cost.I was a rope puller for 20 years,now only do commercial work.Emt to me is the safeist system out there.Should i change my mind on what i want switched or not switched is easy to change anytime.
 
Chicago

Chicago

Don, can you elaborate? What is gained over mc, ac, etc. Why do they have such a code. I know "fire". But its not consistent with NEC.
 
What is gained over mc, ac, etc. Why do they have such a code. I know "fire". But its not consistent with NEC.
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They don't use the NEC in Chicago, there is the Chicago code. Many of the suburbs adopt the NEC with modifications that prohibit the use of most cable wiring methods. I don't know the original reasons.
To keep electricians busy.
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It really doesn't add that many manhours to the job....one of the Joliet area suburbs did a study of the costs for the same house using NM and EMT, the EMT was only 12-15% more expensive so they adopted a pipe code.
Don
 
don_resqcapt19 said:
It really doesn't add that many manhours to the job....one of the Joliet area suburbs did a study of the costs for the same house using NM and EMT, the EMT was only 12-15% more expensive so they adopted a pipe code.
Don
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Fair enough....but the study was done in an area where electricians are allready skilled at wiring homes with pipe. I'll bet if the study was done in other parts of the country, the labor to wire a home with EMT would be significantly higher.
 
Peter,
I'll bet if the study was done in other parts of the country, the labor to wire a home with EMT would be significantly higher.
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The comparison was between a house done in EMT by people who normally do that to a house done in NM by people who normally do that. Have the electricians switch jobs and the labor will be high for both projects.
Don
 
It seems totally impossible that the cost would only be 12-15% more. It seems the material alone would be that much. The labor certainly would be higher. :?
 
Ok, let's do the math. Let's take a base measurement of 500'. In reality, we may have to go much further than that, but let's start there.

A single 500' spool of #12 THHN/THWN is around $40. I need at least 3 colors. That's $120. For 3 spools of THHN I can only go 500 feet. Now, I can buy 2 coils of 12/2 NM for the same price as 3 spools of #12 THHN and go 1000 feet (twice as far).

Also, to go 500' with pipe I need about $150 worth of 1/2' EMT, plus hardware, metal boxes and mud rings.
 
peter d said:
I can buy 2 coils of 12/2 NM for the same price as 3 spools of #12 THHN and go 1000 feet
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NM coils are 250', not 500'

Here goes my estimate to run 500'

3 rolls #12 THHN $120
500' 1/2 EMT $150
straps $ 5
screws $3
couplings $6
connectors $6
25 4" sq. w/ P-rings $35

OR

2 coils NM $120
staples $ 5
25 nailons $10


Pipe method = $325
NM method = $135

I am sure someone out there knows the labor units for pipe and NM.
 
It was done a number of years ago. I was not involved in the study. It appears that if the study was done today, there would be a larger difference.
From an online supplier a foot of 1/2 EMT with 2 #12s would cost 36 cents and 12-2 NM would cost 29 cents.
Don
 
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