Routing 240v 50A around I-Beam

[ZeeResto]

Curious to know how to make a surface mounted run of a 240v 50A #6 wire to get around this I-Beam. Line will enter at house wall seen in the top-right of image and include an outlet box before passing around the I-beam for another 20 feet to a final outlet box.

This is in the garage of a raised ranch home with garage integrated into the house (a bedroom above). Could possibly route into garage ceiling, but this would expose unseen cable to puncture from below.

Circuit will manage a 5,000 Watt / 21A shop heater plus, for now, a 15A 5HP 20 gallon air compressor, with a 23A larger compressor in mind later to replace it.

House is 200A and 60A breaker will be in a 100 sub-panel inside the garage/shop

I am just not experienced working with BX/Ac or conduit to know how to plan curves or "T's" etc.



Thanks for your comments

 

[Jim greengo]

Can you fish romex through the ceiling above the beam?
Or practice your conduit bending skills.

 

[larry4406]

On top of the I-beam there should be a 1.5" sill plate. Cut ceiling drywall, notch out a section of sill plate, kick plate from above, run conduit thru, patch and paint....?

Or use LB's and go under and then back up?

 

[Sokoloff]

I'd use 3/4" EMT conduit. Bend the inside radius to go vertically down, then use two elbows to go horizontally and then back up and then start bending again. It shouldn't be that hard a set of bends to figure out.

3/4" is good for 4 #6 copper THHN.

 

[ard]

....include an outlet box ,....to a final outlet box.

Two 'outlets' on a 50A 240V circuit?

 

[readhead]

Drill a hole in the beam. Do it all the time.

 

[alfredeneuman]

I'd use 3/4" EMT conduit. Bend the inside radius to go vertically down, then use two elbows to go horizontally and then back up and then start bending again. It shouldn't be that hard a set of bends to figure out. 3/4" is good for 4 #6 copper THHN.

I'd suggest the same thing, but with "LB" conduit bodies instead of elbows

 

[OccupantRJ]

Drill a hole in the beam. Do it all the time.

I was going to suggest the same thing, just keep the hole in the upper third of the web.

 

[spudley]

What am I missing? Why can't he go above the beam? I'd rather cut holes in drywall than steel and none of the construction looks finished. Should be plenty of room as the joists run perpendicular to the beam.

 

[PugetDude]

Step drill will go thru the beam; no problem with a conduit sized hole, especially near the end.

 

[ZeeResto]

Two 'outlets' on a 50A 240V circuit?

Yes. To run heater and compressor at same time.

 

[sberry]

Drill or hole saw, couple minutes.

 

[ard]

Yes. To run heater and compressor at same time.

just watch the peak loads and receptacle ratings...

I dont think they make 21A receptacles...nor even 25A. So 2x30A and you are over 50.

Not in actual intended draw, but what COULD happen if someone plugged in loads as 'allowed' by the receptacles/NEMA plug configurations.

I think... a sparky will chime in


PS I dont understand why the wire isnt just in the wall... so no opinions there.

 

[sberry]

Drill or hole saw, couple minutes. Won't mean squat to this beam. As Readhead said, done all the time. Couple drops of Rapid Tap or even water. A hole this size saws fast, I realize not all can do it but I have drilled 3/8 in as little as 35 seconds. Worth buying a bit, 1 1/8.

 

[u2slow]

I would bend two back-to-back offsets. Essentially a saddle bend to get under the beam. No LB fittings, and you can pull the wire in one shot.

 

[u3b3rg33k]

this sounds "wrong" - heater should be on a 30A circuit, "5hp" compressor that pulls 15A isn't putting out 5HP, it's drawing 5hp. should be pulling around 20A if it's got 5 shaft horsepower. that'd be another 30A circuit. also for residential I think you're only allowed 1 outlet per circuit on 240?

just throwing that out there.

 

[wyliesdiesels]

I would not put both of those on the same circuit.

Does the motor nameplate actually say 5HP and 15a? If so that would be a very efficient motor.

If it says 15a but SPL for HP, then its closer to 3HP.

And if the compressor is rated for more than 3HP, then it will need to be hardwired as NEMA plugs do not go above about 3HP.

Does the heater come with an attachment plug? If it does, I bet its a nema 6-30r

The heater instructions should have the circuit requirements and i doubt it calls for a 50a circuit.

Also, if your jurisdiction falls under the international residential building code, then you cannot have multiple 240v outlets on a circuit above 20a.

 

[BD1]

I'd suggest the same thing, but with "LB" conduit bodies instead of elbows

Or use two 1900 boxes instead. Top boxes have bends into them, straight pipe from back of box to box below beam bottom flange.
This will be used as pull boxes too.
You can use the larger 11B boxes too.



Sent from my iPhone using Tapatalk

 

[sberry]

All that stuff will look like Dr. Seuss, like kids did it. Good learning opportunity, put hole in beam. If I was intent on running a single set of wires would put a 6 space on the end and local proper breakers. If I had lots of spaces in main would pull 4 number 10, circuit for both, way easier than wrestling 6 and trying to split.

 

[ZeeResto]

What am I missing? Why can't he go above the beam? I'd rather cut holes in drywall than steel and none of the construction looks finished. Should be plenty of room as the joists run perpendicular to the beam.

Thanks.

I checked on the sole plate and see just a 1" reveal below the finished ceiling.

For locating an existing 12/2 cable for the 120v 20A outlet circuit earlier , I already have a small part of the wall where it meets the ceiling opened up and there I can pass the conduit through to the house side. Inside the house basement, I have access to the floor joists and over the the top of the sub-panel through the common wall top plate which is some 30 inches inside from the I-beam.

So, I'll just come through the top of the common wall, drop down about 10 inches and turn 90 degrees (twice) to run the needed distance to pass under the beam, then turn up again toward locating the rest to the run near the ceiling.

 

[ZeeResto]

Drill or hole saw, couple minutes. Won't mean squat to this beam. As Readhead said, done all the time. Couple drops of Rapid Tap or even water. A hole this size saws fast, I realize not all can do it but I have drilled 3/8 in as little as 35 seconds. Worth buying a bit, 1 1/8.

Thanks, got it.

But as want a receptacle box on the wall to the right of the beam (in the photo) I am already now looking at running below it and it won't look terrible.

Moving to the left past the box, will just turn upward just beyong the beam to return run the thing along the ceiling.

 

[ZeeResto]

just watch the peak loads and receptacle ratings...

I dont think they make 21A receptacles...nor even 25A. So 2x30A and you are over 50.

Not in actual intended draw, but what COULD happen if someone plugged in loads as 'allowed' by the receptacles/NEMA plug configurations.

I think... a sparky will chime in


PS I dont understand why the wire isnt just in the wall... so no opinions there.

Thanks. Maybe you or someone else can review my amperage needs calculations:

At present, with the 21 amp heater / with a 5CFM fan, plus the 15 Amp air compressor I calculated a 75 % margin of safety (under-utilization) like this:

15 x 1.25 = 18.75 + 21 = 39.75 So, a 40A breaker could work, but at the limit, hence the 50A contemplation.

For future with a 23 A compressor (a PUMA 40 gallon model), I calculated like this:

23 x 1.25 = 28.75 + 21 = 49.75 So, within a 50A breaker circuit.

Thoughts?

 

[ZeeResto]

I would bend two back-to-back offsets. Essentially a saddle bend to get under the beam. No LB fittings, and you can pull the wire in one shot.

Hmmm....

 

[ZeeResto]

this sounds "wrong" - heater should be on a 30A circuit, "5hp" compressor that pulls 15A isn't putting out 5HP, it's drawing 5hp. should be pulling around 20A if it's got 5 shaft horsepower. that'd be another 30A circuit. also for residential I think you're only allowed 1 outlet per circuit on 240?

just throwing that out there.

"Rats!" Don't ave room the two, individual circuits. Could run the existing 15A compressor alternately with my welder 30A outlet, though. Don;t need both running at the same time.

 

[Norcal]

"Rats!" Don't ave room the two, individual circuits. Could run the existing 15A compressor alternately with my welder 30A outlet, though. Don;t need both running at the same time.

Will your panel accept a quad breaker? That would be one way get them on separate circuits if the panel manufacturer / listing allows them.

 

[exranger06]

"Rats!" Don't ave room the two, individual circuits. Could run the existing 15A compressor alternately with my welder 30A outlet, though. Don;t need both running at the same time.

If you're running conduit over to this location, why not install a subpanel at the location? You'd only need to run a single circuit through the conduit to feed the subpanel, and then you can run separate circuits from there to the compressor and heater.

 

[ZeeResto]

I would not put both of those on the same circuit.

Does the motor nameplate actually say 5HP and 15a? If so that would be a very efficient motor.

If it says 15a but SPL for HP, then its closer to 3HP.

And if the compressor is rated for more than 3HP, then it will need to be hardwired as NEMA plugs do not go above about 3HP.

Does the heater come with an attachment plug? If it does, I bet its a nema 6-30r

The heater instructions should have the circuit requirements and i doubt it calls for a 50a circuit.

Also, if your jurisdiction falls under the international residential building code, then you cannot have multiple 240v outlets on a circuit above 20a.

The motor is a Dayton 9TC62A and you are correct, it lists HP SPL and not as 5 HP (don't know where I got that idea)

Believe it to be the original motor on this 1999 Speedaire 20 gallon compressor.

The plug has this 6-20P configuration only its molded as part of a 14/3 STO cord.

https://images-na.ssl-images-amazon.com/images/I/516j5-OTl0L._SL1333_.jpg

The heater does not come with a cord.

 

[ZeeResto]

If you're running conduit over to this location, why not install a subpanel at the location? You'd only need to run a single circuit through the conduit to feed the subpanel, and then you can run separate circuits from there to the compressor and heater.

Thanks. Already has a 100A sub-panel and it is from here one or two new circuits will begin.

 

[exranger06]

Thanks. Already has a 100A sub-panel and it is from here one or two new circuits will begin.

OK, so what? You can feed a subpanel from another subpanel.

 

[wyliesdiesels]

Thanks. Maybe you or someone else can review my amperage needs calculations:

At present, with the 21 amp heater / with a 5CFM fan, plus the 15 Amp air compressor I calculated a 75 % margin of safety (under-utilization) like this:

15 x 1.25 = 18.75 + 21 = 39.75 So, a 40A breaker could work, but at the limit, hence the 50A contemplation.

For future with a 23 A compressor (a PUMA 40 gallon model), I calculated like this:

23 x 1.25 = 28.75 + 21 = 49.75 So, within a 50A breaker circuit.

Thoughts?

What youre not factoring in here is in-rush current of the motor.

Also, the larger compressor cannot be on an outlet. it will need to be hardwired.

The motor is a Dayton 9TC62A and you are correct, it lists HP SPL and not as 5 HP (don't know where I got that idea)

Believe it to be the original motor on this 1999 Speedaire 20 gallon compressor.

The plug has this 6-20P configuration only its molded as part of a 14/3 STO cord.

https://images-na.ssl-images-amazon.com/images/I/516j5-OTl0L._SL1333_.jpg

The heater does not come with a cord.

Since it has a 6-20p on it you need to put it on a 6-20r on a 20a circuit.

What is the brand and model of the heater? I suspect the manufacturer calls for a 30a circuit for it and thus a 50a circuit will not work.

 

[ZeeResto]

What youre not factoring in here is in-rush current of the motor.

Also, the larger compressor cannot be on an outlet. it will need to be hardwired.



Since it has a 6-20p on it you need to put it on a 6-20r on a 20a circuit.

What is the brand and model of the heater? I suspect the manufacturer calls for a 30a circuit for it and thus a 50a circuit will not work.

Thanks. It is becoming clearer, unless anything I say from now on is mud....

By the "in-rush of the motor" are you referring to the air compressor? If so, I believed I had considered that when calculating that 15A x 1.25 = 18.75A and then adding the 21A heater for under 40A. Then making it a 50A circuit to begin with for capacity in the future.

The heater is DuraHeat model EWH5500 requiring a minimum 10 gauge SJO of SJTO copper wiring. 240V/60hz 21A 5000 Watts, 17060 BTU/Hr, 1 phase minimum 30AMP circuit.

Questions:

1. Why won't the 21 A heater work in a 50A circuit if a 30A receptacle is used? We do it all the time when plugging a <15A portable radio into a 20A kitchen outlet circuit, for example. Don't understand why an outlet limiting one or both of these loads to a lesser amperage is somehow harmful to protecting the circuit wiring or breaker.

Can you please explain? (not challenging your authority here, just inquisitive)

2. If I can run separate circuits, say a 240, 20A for the Speedaire and a 30A for the DuraHeat, can I pass all wires through the same PVC conduit until dropping out a couple outlet boxes along the <30 foot run? The air compressor is under 8' away from the sub-panel.


BTW, PUMA says the TE-5040v model air compressor lists 21 A at 230v. I have 240v. That 23A in my original post is at 208V
Thanks again.

 

[u3b3rg33k]

Questions:

1. Why won't the 21 A heater work in a 50A circuit if a 30A receptacle is used? We do it all the time when plugging a <15A portable radio into a 20A kitchen outlet circuit, for example. Don't understand why an outlet limiting one or both of these loads to a lesser amperage is somehow harmful to protecting the circuit wiring or breaker.

Can you please explain? (not challenging your authority here, just inquisitive)

2. If I can run separate circuits, say a 240, 20A for the Speedaire and a 30A for the DuraHeat, can I pass all wires through the same PVC conduit until dropping out a couple outlet boxes along the <30 foot run? The air compressor is under 8' away from the sub-panel.


BTW, PUMA says the TE-5040v model air compressor lists 21 A at 230v. I have 240v. That 23A in my original post is at 208V
Thanks again.

1: code says so.

also, an outlet does not limit anything. it's just a connection. also, circuit breakers don't limit anything either. they just stop things when they go too far.

but practically it comes down to appliance application. most 120V appliances (phone chargers, computers, TVs, lights, etc). don't use the whole circuit's capacity. most 240V appliances do.

in cases where there's a 120V appliance that is likely to need the full capacity of the circuit, code says you need a dedicated circuit (microwaves, fridges, garbage disposal, etc).

15A@ 120V 1.8kW (1.4kW cont)
20A @ 120V is 2.4kW (2kW cont). a little different. (about 30%)

30A@ 240V is 7.2kW (6.2kW cont)
50A@ 240V is 12kW (9.6kW cont) a bigger difference (about 65%)

2: if you size the conduit appropriately I believe that's fine.

 

[ZeeResto]

1: code says so.

also, an outlet does not limit anything. it's just a connection. also, circuit breakers don't limit anything either. they just stop things when they go too far.

but practically it comes down to appliance application. most 120V appliances (phone chargers, computers, TVs, lights, etc). don't use the whole circuit's capacity. most 240V appliances do.

in cases where there's a 120V appliance that is likely to need the full capacity of the circuit, code says you need a dedicated circuit (microwaves, fridges, garbage disposal, etc).

15A@ 120V 1.8kW (1.4kW cont)

20A @ 120V is 2.4kW (2kW cont). a little different. (about 30%)

30A@ 240V is 7.2kW (6.2kW cont)
50A@ 240V is 12kW (9.6kW cont) a bigger difference (about 65%)

2: if you size the conduit appropriately I believe that's fine.

Might as well use two 30A dedicated circuits and then cut off that 6-20p and replace it with a 6-30p to be compatible with code needing all receptacles to be the same, yet incomprehensible to me why.

 

[sberry]

1. Why won't the 21 A heater work in a 50A circuit if a 30A receptacle is used? We do it all the time when plugging a <15A portable radio into a 20A kitchen outlet circuit, for example. Don't understand why an outlet limiting one or both of these loads to a lesser amperage is somehow harmful to protecting the circuit wiring or breaker.

Can you please explain? (not challenging your authority here, just inquisitive)

15 ends are designed for 20 circuits, the 120V with this end has wire and internals engineered to handle short circuits with this breaker, they are for use on general circuits. If equipment comes factory cord and end then that is the limit of the circuit it can be installed on due to the fact it is again designed with short circuit in mind, lots of 20 ends on 14 cords but that's the limit, they do not want it on 50A, its internals not designed for it, cord may not be sized for it. When it doesn't come cord and plug then it is the responsibility of the installer to make sure it all matches, it needs adequate wire to run it and then limited ocpd for short,, or faults. There are some fundamental rules with this,,, 12 cords limited to 50, 14 to 30, 10 to 60 etc. That is not to size the load, the breaker doesn't do that, the wire does. When if comes factory plug the mfg has already determined all this and puts a plug on with this limit. No installing recepts with breaker larger than their rating and in most cases with the exception of welders the wire needs to match a recept. Sposed to be a known deal, 30 wire, 30 recept, 30 breaker.
Clear as mud?

 

[matt_i]

I was going to suggest the same thing, just keep the hole in the upper third of the web.

nooooooooOooooooo!

Drill in the middle third of the web. Ideally you want to drill on the neutral axis (horizontal centerline between the flanges) where no bending stress is carried, only the horizontal shear....of which the steel is more than capable. The farther the hole is drilled away from the neutral axis, the more the beam is compromised.

The regulations are the same for wood framing: do not drill (or notch!!!) in the upper or lower 1/3 of the joist....

Just want to make sure the O.P. doesn't make a serious mistake.

 

[ZeeResto]

nooooooooOooooooo!

Drill in the middle third of the web. Ideally you want to drill on the neutral axis (horizontal centerline between the flanges) where no bending stress is carried, only the horizontal shear....of which the steel is more than capable. The farther the hole is drilled away from the neutral axis, the more the beam is compromised.

The regulations are the same for wood framing: do not drill (or notch!!!) in the upper or lower 1/3 of the joist....

Just want to make sure the O.P. doesn't make a serious mistake.

No worry. In my newest thinking about routing, it'll be below that I-beam by the time it goes the 20 inches to get past it before turning up to the ceiling.

Thanks for your guys thoughts

 

[exranger06]

Questions:

1. Why won't the 21 A heater work in a 50A circuit if a 30A receptacle is used? We do it all the time when plugging a <15A portable radio into a 20A kitchen outlet circuit, for example. Don't understand why an outlet limiting one or both of these loads to a lesser amperage is somehow harmful to protecting the circuit wiring or breaker.

Can you please explain? (not challenging your authority here, just inquisitive)

It's because the appliance that's plugged into a 30A receptacle SHOULD use only 30A max, but what if the appliance malfunctions and it starts drawing more than that? The breaker will trip if it goes over 50A, but what if it stays at around 40A? The receptacle can only handle 30A. It can start to melt, burn and start a fire and the breaker will never trip to stop it.

An appliance that draws 4A can be plugged into a 15A receptacle because the receptacle can handle 15A, and it's on a 15A breaker. If the current goes above 15A, the breaker tops before any damage happens to the receptacle.

 

[sberry]

It's because the appliance that's plugged into a 30A receptacle SHOULD use only 30A max, but what if the appliance malfunctions and it starts drawing more than that? The breaker will trip if it goes over 50A, but what if it stays at around 40A? The receptacle can only handle 30A. It can start to melt, burn and start a fire and the breaker will never trip to stop it.

An appliance that draws 4A can be plugged into a 15A receptacle because the receptacle can handle 15A, and it's on a 15A breaker. If the current goes above 15A, the breaker tops before any damage happens to the receptacle.

Sort of not exactly. It really won't just start drawing more. The reason it's limited to 30 is the internals are not rated for faults above that. Lots of cords, lots of 14 wire is allowed on 30A, it's thermally limited by its design or additional internal protection. Think Christmas lights, wire so fine it won't fault 20 breakers, won't trip them on thermal so they add a fuse.
Things that pull 4 a on 20 are designed for it. Lots of stuff on dedicated has no internal protection, all its components and wire designed to carry it's connected load but heavy enough to fault the breaker.
There is a notion that breaker only protects the circuit wire which is not true and often not the case except for general 120v with multiple outlets. AN electric range is a good example, a 225 buzzer welder is somewhat an example, connected by a 12 cord with no thermal. A range is a bunch of circuits, all 12 wire from each burner spliced to a cord that can't be overheated by the combination of all the loads, sized so a fault from any wire will trip up a 50.

 

[sberry]

Look at cooking equipment, one of the places putting 2 pieces on the same circuit is allowed. These are different than a range where it's all one unit. They are limited to 30 or 50 depending on design, could put 2 ovens or a cook top and oven on a 30A circuit, they have 14 wire. Same for 50, each has a 12. Thesee are hard wired, no recept. A recept tells that it is available, that the wire size is adequate and that it has proper overcurrent. It's why some home brew adapters, a 50 to a 20 is not legal, the device being plugged in to it is not suffecient for that high current limit.
A 50 to 30 for a travel trailer may be fine, the 10 wire to the trailer is good for shorts, it has further protection in the trailer (similar to being a power strip) which limits the thermal to protect the wire and has 15 or 20 breakers to limit short circuit for 120,v equipment.

 

[sberry]

A common power strip is designed along some of these principles, cant overload a 20A with a strip with additional breaker. It's different than a simple 3 way which simply provides more recepts and will pass thru 20A. A strip has breaker that protects the 14 wire AHEAD of it. Just limits the thermal draw to 14 , plugged in to 20A. If the strip has a 16 cord and multiple outlets then it has 10A breaker, 20 protects it from fault till it gets to the 10 which does thermal. (Probably trip from internal fault also] this is all generalization.