Conduits In A Slab

[Alwayslearningelec]

If you had a job that allowed conduits in a slab how do you decide which systems such as feeders, lighting, wiring devices, HVAC etc. you would put in the slab and which you don't. I imagine apce is a consideration and depth of slab. Lets say it is a 24" slab.

Thanks.

 

[cowboyjwc]

I would probably not put anything in the slab that I may need to get to again. So, you should never have to mess with the feeder, but if it was in say a strip center I would probably make it larger to accomedate an upgrade. Things like lights and plugs, I would say over head.

 

[iwire]

I imagine apce is a consideration and depth of slab. Lets say it is a 24" slab.

Thanks.

You have a 24" thick slab? :?

If so I would check the specs and see if the engineer will even allow you to run conduits in it.

If we are talking about a slab on grade we will put as much as possible under it.

If we are talking a slab deck you really only can put the required branch circuits in it, you will not be running a 2" feeder in a 4" slab.

 

[Alwayslearningelec]

You have a 24" thick slab? :?

If so I would check the specs and see if the engineer will even allow you to run conduits in it.

If we are talking about a slab on grade we will put as much as possible under it.

If we are talking a slab deck you really only can put the required branch circuits in it, you will not be running a 2" feeder in a 4" slab.

I think that was the slab on grade. I looked quickly( I'm not doding feeders etc.). I am just doing a device take-off but was curious how this issue was approached. I think the deck slabs are 6".

I though maybe you might try to throw as much as possible in the deck. Thanks.

 

[chris kennedy]

If we are talking about a slab on grade we will put as much as possible under it.

Agreed, as much as time allows.

 

[luckylerado]

I will always put as much as possible under the slab. I try to only put 2 ckts max in each pipe to allow for adds or goofups. I always run 4" to the transformer pad and if possible put in a spare 4" (commercial) and I never use 1/2" under-slab. 3/4 or larger. The only thing that I have learned does not belong under-slab is shielded wire. PVC inevitably will have some water in it and one little nick in a shelided wire can cause all kinds of troubleshooting. I also recommend using rigid 90s to come up out of the slab and I have almost never been allowed to put anything in a slab on deck. One last bit of advise. If you do decide to go underneath don't just put some first year monkeys out there to run it or all the time and money you would have saved will be lost to saw cutting and jack hammering.:happysad:

 

[Alwayslearningelec]

You have a 24" thick slab? :?

If so I would check the specs and see if the engineer will even allow you to run conduits in it.

If we are talking about a slab on grade we will put as much as possible under it.

If we are talking a slab deck you really only can put the required branch circuits in it, you will not be running a 2" feeder in a 4" slab.

So you would put lighting and wiring device branch circuits in the slab?

 

[Alwayslearningelec]

I would probably not put anything in the slab that I may need to get to again. So, you should never have to mess with the feeder, but if it was in say a strip center I would probably make it larger to accomedate an upgrade. Things like lights and plugs, I would say over head.

What exactly do you mean when you say "get to again". What might you have to do? THanks.

 

[Alwayslearningelec]

I thought electricians try to get a lot in the slab. If allowed doesn't it save time??

 

[Cow]

A tenant space in a strip mall for instance. He's saying the main feeders would probably be alright underground, but lights/receptacle circuits underground would probably be a bad idea. Tenant spaces are always changing, walls removed/relocated. A recep circuit coming up underground into a wall that gets removed in a future remodel is worthless. You end up cutting the conduit off flush and going overhead. Where as feeders are probably alright, since the panels they're feeding don't usually move.

 

[Alwayslearningelec]

A tenant space in a strip mall for instance. He's saying the main feeders would probably be alright underground, but lights/receptacle circuits underground would probably be a bad idea. Tenant spaces are always changing, walls removed/relocated. A recep circuit coming up underground into a wall that gets removed in a future remodel is worthless. You end up cutting the conduit off flush and going overhead. Where as feeders are probably alright, since the panels they're feeding don't usually move.

Makes sense. THanks

 

[jrannis]

I would try to put any large equipment circuits and home runs in the slab. Next on the list would be all larger sizes of data and communications, next would be trying to hit outside walls and connecting the receptacles together and maybe tying them together in one extra place just in case one conduit gets damaged.
Make sure you understand all of the circuits you will need to pull and route the underground accordingly or you could end up pulling much more wire than necessary.

 

[Alwayslearningelec]

I would try to put any large equipment circuits and home runs in the slab. Next on the list would be all larger sizes of data and communications, next would be trying to hit outside walls and connecting the receptacles together and maybe tying them together in one extra place just in case one conduit gets damaged.
Make sure you understand all of the circuits you will need to pull and route the underground accordingly or you could end up pulling much more wire than necessary.

Thanks.

 

[cowboyjwc]

A tenant space in a strip mall for instance. He's saying the main feeders would probably be alright underground, but lights/receptacle circuits underground would probably be a bad idea. Tenant spaces are always changing, walls removed/relocated. A recep circuit coming up underground into a wall that gets removed in a future remodel is worthless. You end up cutting the conduit off flush and going overhead. Where as feeders are probably alright, since the panels they're feeding don't usually move.

Wow that's the second time in two days that I haven't had to explain my answer. Good job cow.:happyyes:

 

[BJ Conner]

And Information Allows.

And Information Allows.

Agreed, as much as time allows.

Put in all you can that time allows and information allows as well.
Equipment lcoations ( things like chillers, pumps etc.) have a way of moving. Walls move as well.
Terminate your conduits with flush couplings- it makes it easier to hide where you missed ( or where you got the wrong information).

 

[wawireguy]

I thought electricians try to get a lot in the slab. If allowed doesn't it save time??

Aren't you an electrician?

Put as much as you can in the slab for home runs to your panels. Watch your larger conduits like a hawk. Get in strings as soon as they backfill or pour as some might get broken and will need repairing.

 

[Cow]

Wow that's the second time in two days that I haven't had to explain my answer. Good job cow.:happyyes:

Maybe I'll start using really short responses in the hopes you can return the favor!

 

[kwired]

You should also run under the slab to get to floor outlets in the slab:happyyes:

 

[cdslotz]

So you would put lighting and wiring device branch circuits in the slab?

Hardly ever, sometimes it's necessary if there is a high area you don't want to go over.
Most spec don't allow conduits IN the deck, because of future core drilling for poke-thru's etc.
If you have a deck, you can go under it.

 

[cdslotz]

Just to clarify, I'm talking about conduits in the deck.
Slab on grade we put as much as possible, especially feeders. They require trenching/backhoe, compaction.