Electrical Conduit Through Concrete Floor

Local codes are different. Consult your local government agency that will handle the inspection and ask them.

Or, at least tell your location.

I don't know where you are, but I am alarmed that you ask the question, an elevated reinforced concrete floor needs the attention of a qualified, licensed, engineer.

If I was doing this, I would look at using cellular metal deck or a mix including some cellular. It is a stay in place formwork and, if you use a composite deck you might be able to use less concrete and only a small amount of shrinkage reinforcement. It is used in many office and industrial buildings to allow future uses different to the original design.

A 3" cellular deck is shown http://www.dek-ing.com/dekfloor-n2418cellcomposite.html

Please don't be alarmed. The floor has been designed by a civil engineer and it's my own home. Here in Ontario, Canada, homeowners can install their own electrics. From my limited understanding of the Ontario building code, it says 1" max for combustible raceways to maintain "fire separation" On the other hand being a resisidence that is fully detached, maybe fire separation is a non-issue.

The other part of my question was whether 4 x 1" dia conduit was enough for a 230 FT2 greenhouse, for lighting fans and controls. The floor is heated with hydronics so electric heat will not be used.

Any recommendations will be appreciated.

Thank-you,

Ted.

How big is the area?

Length width height

What equipment are you putting in there?

How do you have a civil engineer design the floor?

If you do not have the weight of equipment

If you know the weight?

You know the load requirements?

You have the electrical load

Your next step is to calculate

Circuits, voltage, amp

Wire size

Distance of your from distribution

To point of use (location of equipment)

Adjust wire size for voltage drop for distance

And now you have what you will use

Keep in mind

Not have more than 3 circuits in

1 electrical raceway run max (tube thru floor)

Adjust your tubing for wire size

And leave a 24 in open for all the rest (Joke)

Match your design plan to local codes

Use a steel oversize pipe thru floor

Project 1 inch above concrete floor

And 1 inch below concrete floor (ceiling)

Stuff inside with Styrofoam , toilet paper, penthouse

Pour concrete, remove foam, or pics

Run your electrical pipes PVC / EMT?

Thru sleeve

Then use fire retardant foam filler between sleeve and PVC / EMT

fillers are rated for fire per hr per deg

And note I could be wrong

oh why is there double space when I type

Hi Ted,

It's been a number of years since I have had to deal with fire penetration issues for piping and conduits (in Vancouver) and I am not familiar with the Ontario Building Code, except that it is likely derived from the National Building Code.

Locally, for single family residences, fire codes do not require the same treatments as for commercial or multi-residential units. For detailing of firestopping and penetrations through various structures (wood and concrete) of various FRR I have used the details from Passive Fire Protection Partners (formerly Firestop Systems). You can likely find what you are looking for there in terms of detailing based on the construction. I would double check with the local code or code officials though just to be sure regarding any code issues and applicability. Although they may allow you to perform your own work, they will likely still require an inspection to ensure it is "kosher".

As for the other part of your question regarding capacity of what you propose, I cannot say as my background is in Mechanical engineering, not Electrical.

Here's the penetration detail link: http://www.firestop.com/listings/searchmain.asp

Cheers,

Duane Tilden, P.Eng

you can go ahead i have done it in several commercial projects including several Star hotels in India In fact you can create duct in the slab for electrical cables in consultation with your Civil/structural engineer, only precaution to taken is to insure your PVC conduit doesn't get chocked while pouring concrete.and insure that both ends of the concrete are plugged before you pore the concrete

crm

sorry for the error in my last sentence i meant both ends of conduit not concrete

crm

Your fine, just be sure you fireseal any gaps once you run the conduit and circuits. UL/CSA rated PVC conduit meet all fire requirements of most countries.

Use a female adapter on the pvc pipe and screw on Rigid Steel Conduit 90 to stub-up through the concrete. (Factory steel 90's are readily available) Tape the steel from just above to just below where the surface of the concrete will be, because this is a very corrosive area. This will protect the conduit from rusting-out where it exits the concrete.

How many floors you have?

Where is the pipe running from and to?

The size of the pipe is more than enough for many wires! However; if you are planning on running more than 4 conductors other than the ground wire (green or bare) you need to consider the increase of the size of wires.

You can use table 310.15(B) (2) (a) NEC 2005.

Once you determine the factor, use table 310.16 NEC 2005 to choose the right size wire.

mike holt website has soom good tools tou can use.

MCS Electrical

www.mcselerctricalinc.com