What would you do?

[titan1021]

I have been asked to install a receptacle for a large freight company in one of their distribution warehouses. The warehouse is 225'x 200' and of course they need a receptacle for a computer station on the complete opposite side of the warehouse from where the sub-panels are located.

I've got two options for routing the conduit and wiring to the desired location.

Option 1: Across the 30ft high steel truss ceiling creating a run of approx. 360' and a lot of extensive lift work.

Option 2: Utilizing an existing conduit that is run approx halfway to the desired location, by continuing the run along approx. 200' of a
conveyor belt system for a total run distance of approx. 460' (no overhead work required with this option)

When doing voltage drop calcs.

I come up with #4 for 360' at 120v 15amp (3% VD)

I come up with #3 for 460' at 120v 15amp (3% VD)

I looked into Buck Boost transformers but am not really familiar with them, I did see that they aren't recommended for vary load demands.
So am not sure the voltage coming from the transformer would be safe for the computers, should someone also plug another load in.

There is a 277v lighting panel that I can also access. Another option would be to run 277v to the location then step it down with a small transformer.

That calcs out at

#6 for 360' at 277v for 15amp (3% VD)

#6 for 460' at 277v for 15amp (3% VD)

Just hoping to get a little advice or input on which method would be the better way to go.

Thank you

 

[Fulthrotl]

I have been asked to install a receptacle for a large freight company in one of their distribution warehouses. The warehouse is 225'x 200' and of course they need a receptacle for a computer station on the complete opposite side of the warehouse from where the sub-panels are located.

I've got two options for routing the conduit and wiring to the desired location.

Option 1: Across the 30ft high steel truss ceiling creating a run of approx. 360' and a lot of extensive lift work.

Option 2: Utilizing an existing conduit that is run approx halfway to the desired location, by continuing the run along approx. 200' of a
conveyor belt system for a total run distance of approx. 460' (no overhead work required with this option)

When doing voltage drop calcs.

I come up with #4 for 360' at 120v 15amp (3% VD)

I come up with #3 for 460' at 120v 15amp (3% VD)

I looked into Buck Boost transformers but am not really familiar with them, I did see that they aren't recommended for vary load demands.
So am not sure the voltage coming from the transformer would be safe for the computers, should someone also plug another load in.

There is a 277v lighting panel that I can also access. Another option would be to run 277v to the location then step it down with a small transformer.

That calcs out at

#6 for 360' at 277v for 15amp (3% VD)

#6 for 460' at 277v for 15amp (3% VD)

Just hoping to get a little advice or input on which method would be the better way to go.

Thank you

i had a similar situation a few years ago.

if you pull a ground, it has to be the same size as the ungrounded conductors.
i was out to #2 copper for a 7 amp load, and the #2 ground chafed a bit. ended
up using the raceway as a ground, one of the few times i've done that intentionally.

the transformer is a solution. 480/120 will keep your voltage drop within reason.
i'm doing one tomorrow on a piece of moving conveyor, that needs 120 volts to power
some work lights while the thing is moving... a 1 KW single phase feeding three led wall
packs.

 

[ActionDave]

....

When doing voltage drop calcs.

I come up with #4 for 360' at 120v 15amp (3% VD)

I come up with #3 for 460' at 120v 15amp (3% VD)

Where are you coming up with 15A? Why do you think you need to keep VD at 3%?

 

[titan1021]

Where are you coming up with 15A? Why do you think you need to keep VD at 3%?

I would like to provide them with 15amps at that location, should they decide to put more loads on that receptacle in the future being that there is no other receptacle within 100' of that location.

Always heard that 3% was a good rule of thumb, even though most loads can handle +/- 5% without a problem.

 

[ActionDave]

I would like to provide them with 15amps at that location, should they decide to put more loads on that receptacle in the future being that there is no other receptacle within 100' of that location.

Always heard that 3% was a good rule of thumb, even though most loads can handle +/- 5% without a problem.

I don't do math and I don't worry so much about VD as others. I would run 10AWG and bet you my next two pay checks that the customer will not have a problem.

 

[titan1021]

I don't do math and I don't worry so much about VD as others. I would run 10AWG and bet you my next two pay checks that the customer will not have a problem.

I had someone else tell me almost the same thing. This is going to be an expensive receptacle, just hate to run 10's and end up having a problem and re-doing the work.

Sent from my SM-N920P using Tapatalk

 

[ActionDave]

I had someone else tell me almost the same thing. This is going to be an expensive receptacle, just hate to run 10's and end up having a problem and re-doing the work.

Sent from my SM-N920P using Tapatalk

Run 8AWG if it makes feel better. At least then you could still use 3/4" pipe. All I can tell you is I have run three and four hundred feet on 10AWG with no problems.

 

[titan1021]

Run 8AWG if it makes feel better. At least then you could still use 3/4" pipe. All I can tell you is I have run three and four hundred feet on 10AWG with no problems.

Good to know,#4 & 6 seems like total overkill.

Sent from my SM-N920P using Tapatalk

 

[iwire]

I don't do math and I don't worry so much about VD as others. I would run 10AWG and bet you my next two pay checks that the customer will not have a problem.

Dave, this is not great advice.

Because if the customer does have a problem you look like an idiot and it costs a lot more to do it right the second time.

On top of that we make our living installing electrical work, as long as the job estimate is done right we make more when the job costs more.

 

[iwire]

Good to know,#4 & 6 seems like total overkill.

Sent from my SM-N920P using Tapatalk

But they may not be, I did a food distribution warehouse where all RTU service outlets where wired with 4 AWG. That was an engineered job.

 

[Fitzdrew516]

Dave, this is not great advice.

Because if the customer does have a problem you look like an idiot and it costs a lot more to do it right the second time.

On top of that we make our living installing electrical work, as long as the job estimate is done right we make more when the job costs more.

Agreed.
If you're trying to run smaller wire than what you calculated then I would suggest only using the load of whatever is going to be plugged in to this receptacle. I know you said you want them to be able to utilize it if they need it in the future, and that's good practice, but since you think you're going overkill on this one I think I'd just explain to the customer his/her options.

1 - The cheaper option would be to use a smaller wire and explain to them it is sized only for what they are using it for now.
2 - Size it for the full 15A and tell them they will be able to plug a few miscellaneous items in later if they want.

I like putting the ball in the customer's court because most likely when they see the cost difference for it they'll go with the cheaper option, and although they may plug other things into it at least you've explained to the customer that it isn't designed for that. I'd send an email with this info to the customer so you have it in writing just in case.

 

[iwire]

I like putting the ball in the customer's court because most likely when they see the cost difference for it they'll go with the cheaper option, and although they may plug other things into it at least you've explained to the customer that it isn't designed for that. I'd send an email with this info to the customer so you have it in writing just in case.

I agree, this is the way to handle it, present the price both ways and let the customer decide.

 

[luckylerado]

It has been discussed by members here in the past the California Title 24 has made voltage drop compliance mandatory. The calculation method is given is section 8.4

Thank God too because someone needs to offset the greenhouse gases released by that Methane leak.

 

[iwire]

I don't do math and I don't worry so much about VD as others. I would run 10AWG and bet you my next two pay checks that the customer will not have a problem.

Here is a real world example of when this method bit the company I work for in the rear.

A supermarket chain has peanut grinders for customer use, often 4 to 8 of them lined up in the bulk nut aisle. Each on a dedicated 20 amp 120 volt circuit. We wired them without concerning ourselves with voltage drop. Well that failed, in the morning at first use they would trip the breakers.

A crew was sent in and replaced the 12s with 10s, nope another fail. I think we ended up using 6s.

The problem is that overnight the product stiffens up and needs full power of the motor to break free. The voltage drop would let the machine sit there in a locked rotor condition until the breakers would trip.

(The machines should probably come with factory 30 amp cord caps but I bet that reduces sales)

That said, for lighting circuits and such I have much less worry about some voltage drop.

 

[Fitzdrew516]

It has been discussed by members here in the past the California Title 24 has made voltage drop compliance mandatory. The calculation method is given is section 8.4

Thank God too because someone needs to offset the greenhouse gases released by that Methane leak.

Most states require voltage drop to be under a certain threshold if you look at the energy codes. California just takes it to a whole new level of stupid. They make you list the VD of every single piece of wire in the building. Pretty sure the last California job I did I had a table with like 500 different line items of different voltage drops listed.

 

[ggunn]

Most states require voltage drop to be under a certain threshold if you look at the energy codes. California just takes it to a whole new level of stupid. They make you list the VD of every single piece of wire in the building. Pretty sure the last California job I did I had a table with like 500 different line items of different voltage drops listed.

Excel is your friend.

 

[Fitzdrew516]

Excel is your friend.

It was, it was... Also got to add 2 sheets to my drawing set just for voltage drop tables. Wasting paper - not very green are we, California?

 

[titan1021]

But they may not be, I did a food distribution warehouse where all RTU service outlets where wired with 4 AWG. That was an engineered job.

I normally always go by the voltage drop calculations, because you can't go wrong with the installation and its the best way to cover your ass.
Installing #4's and the larger conduit needed would be extremely costly for a single duplex receptacle.

 

[titan1021]

Agreed.
If you're trying to run smaller wire than what you calculated then I would suggest only using the load of whatever is going to be plugged in to this receptacle. I know you said you want them to be able to utilize it if they need it in the future, and that's good practice, but since you think you're going overkill on this one I think I'd just explain to the customer his/her options.

1 - The cheaper option would be to use a smaller wire and explain to them it is sized only for what they are using it for now.
2 - Size it for the full 15A and tell them they will be able to plug a few miscellaneous items in later if they want.

I like putting the ball in the customer's court because most likely when they see the cost difference for it they'll go with the cheaper option, and although they may plug other things into it at least you've explained to the customer that it isn't designed for that. I'd send an email with this info to the customer so you have it in writing just in case.

Great suggestion!

 

[ActionDave]

Agreed.
If you're trying to run smaller wire than what you calculated then I would suggest only using the load of whatever is going to be plugged in to this receptacle. I know you said you want them to be able to utilize it if they need it in the future, and that's good practice, but since you think you're going overkill on this one I think I'd just explain to the customer his/her options.

1 - The cheaper option would be to use a smaller wire and explain to them it is sized only for what they are using it for now.
2 - Size it for the full 15A and tell them they will be able to plug a few miscellaneous items in later if they want.

I like putting the ball in the customer's court because most likely when they see the cost difference for it they'll go with the cheaper option, and although they may plug other things into it at least you've explained to the customer that it isn't designed for that. I'd send an email with this info to the customer so you have it in writing just in case.

I agree with this also.

That said I remain steadfast in my opinion that there is no need for 4 or 3AWG for what is basically a convenience receptacle.