Spider boxes

[Isaiah]

And those connectors have to be supplied from a CB with a rating < or equal to the connector's rating. See table Table 210.21(B)(3) 50A receptacle is allowed to be on a 40A or 50A circuit and that's it.

Actually, that’s not what it says. But I agree ideally it should be a 50A CB. There isn’t enough argument here to change the installation. Maybe you could submit a PI to include the word “connector” within the verbiage since currently it doesn’t exist


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[Todd0x1]

Actually, that’s not what it says. But I agree ideally it should be a 50A CB. There isn’t enough argument here to change the installation.


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I wouldn't change the installation either, because we all know 10 extra amps isn't going to melt a 50A receptacle. I REALLY wish UL would come up with a revised standard for those that makes them good for 60 amps while being backwards compatible with existing 50 amp ones.

As far as "that's not what it says" please explain. -Nevermind I see what you're talking about with connector. I believe, and someone please correct me if I am wrong, code treats what we call a connector (in the context of cord attachment) as a receptacle if its female. Regardless you have a 50 amp receptacle on the pass though side of the spider box.

Then there is the whole 'follow the mfgr instructions" -I forget what code section that is.

I have a manual infront of me from a Southwire 6506UGSX spider box, it #1 under operating instructions says "Connect the 50A inlet to a 125/250v 50A power source"

 

[Todd0x1]

I believe, and someone please correct me if I am wrong, code treats what we call a connector (in the context of cord attachment) as a receptacle if its female.

Ah, here we go. In 210.50
(A) Cord Pendants. A cord connector that is supplied by a
permanently connected cord pendant shall be considered a
receptacle outlet.

 

[Isaiah]

Ah, here we go. In 210.50
(A) Cord Pendants. A cord connector that is supplied by a
permanently connected cord pendant shall be considered a
receptacle outlet.

Yes but you do realize this is a temporary construction install? The cord, I.e. power, will be disconnected and removed within a couple weeks


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[winnie]

1) Being temporary doesn't change the code. Substandard situations might be allowed to slide, or you might have a situation permitted in the article on 'temporary wiring', but 'it's temporary' is not a get out of jail free card.

2) That thing built into the box with the blades sticking out? It is a 'receptacle inlet', differentiated from the thing on the wall with the slots, called a 'receptacle outlet'. It is still a receptacle, though arguably not part of building wiring.

3) I think you are misunderstanding the use of breaker '80%' ratings. The 80% rating is a limitation of the breaker; a normal 80% breaker is only permitted to carry 80% of its trip rating on a continuous basis. But this limit doesn't change the protection provided by the trip rating.

If you have devices, wires, receptacles, etc. which require 50A protection, then you need to use a 50A breaker. If that breaker is a common 80% rated breaker, then you will be restricted to 40A of continuous load.

If you take the code sections related to the 80% breaker rating as a whole, you see that wires are sized to 125% of any continuous load, and the breaker similarly sized, so that the breaker is matched to the wire and the load is no more than 80% of the breaker rating.

Jon

 

[Isaiah]

1) Being temporary doesn't change the code. Substandard situations might be allowed to slide, or you might have a situation permitted in the article on 'temporary wiring', but 'it's temporary' is not a get out of jail free card.

2) That thing built into the box with the blades sticking out? It is a 'receptacle inlet', differentiated from the thing on the wall with the slots, called a 'receptacle outlet'. It is still a receptacle, though arguably not part of building wiring.

3) I think you are misunderstanding the use of breaker '80%' ratings. The 80% rating is a limitation of the breaker; a normal 80% breaker is only permitted to carry 80% of its trip rating on a continuous basis. But this limit doesn't change the protection provided by the trip rating.

If you have devices, wires, receptacles, etc. which require 50A protection, then you need to use a 50A breaker. If that breaker is a common 80% rated breaker, then you will be restricted to 40A of continuous load.

If you take the code sections related to the 80% breaker rating as a whole, you see that wires are sized to 125% of any continuous load, and the breaker similarly sized, so that the breaker is matched to the wire and the load is no more than 80% of the breaker rating.

Jon

None of the loads are continuous. So the 40%/80% restrictions do not apply. I believe the issue of receptacle inlet vs receptacle outlet are different functions but I also believe the CB should be restricted to 50A as sort of a ‘default scenario’ since there is no precise language to address it.


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[norcal]

All the spider boxes I have seen have a 50A locking flanged inlet & a 50A locking receptacle, so how can a 60A breaker be used?

 

[Isaiah]

All the spider boxes I have seen have a 50A locking flanged inlet & a 50A locking receptacle, so how can a 60A breaker be used?

All loads are non continuous. All branch circuits within the box are protected per NEC 240. The feeder cable to the box is sized at 65A…please explain — how is this unsafe?


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[winnie]

The receptacles are rated for 50A of current, protected by a 60A breaker.

Code requires 50A receptacles to be protected by 50A breakers.

Exactly how unsafe is this? Probably not much. We don't know the actual current handling capacity of the various connectors, only that they are in a 50A configuration.

Jon

 

[Isaiah]

The receptacles are rated for 50A of current, protected by a 60A breaker.

Code requires 50A receptacles to be protected by 50A breakers.

Exactly how unsafe is this? Probably not much. We don't know the actual current handling capacity of the various connectors, only that they are in a 50A configuration.

Jon

The fact is, it is NOT unsafe and meets the intent of the code. Purists will say it’s not code compliant, and they have a point. Nonetheless, there isn’t enough argument to modify installation especially since it will be dismantled with a week or two.


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[winnie]

It does not meet the intent of code, and explicitly violates code sections posted by others.

You can assert without evidence that it isn't that unsafe, and I would agree with you.

But based on your previous comments about 125% requirements for continuous loads, you misunderstand the reason for those code sections, and that misunderstanding leads you to think this installation meets the intent of the code.

Try again: how does a 50A device on a 60A breaker meet the intent of the code?

Jon

 

[ActionDave]

I would hook it up that way and not worry a bit about it. There is no rule that allows a 50A recpt on a 60A breaker, but the principal still exists. The code has many places where it allows some wiggle room on sizing wires. We can put 90A wire on a hundred amp breaker because of load diversity, we can put 4/0 AL on a 200A breaker because of the next size up rule. It may not have the blessing of the so-called team of experts that write the code, but it's not unsafe.

 

[Isaiah]

It does not meet the intent of code, and explicitly violates code sections posted by others.

You can assert without evidence that it isn't that unsafe, and I would agree with you.

But based on your previous comments about 125% requirements for continuous loads, you misunderstand the reason for those code sections, and that misunderstanding leads you to think this installation meets the intent of the code.

Try again: how does a 50A device on a 60A breaker meet the intent of the code?

Jon

I didn’t misunderstand anything. For continuous loads the CB is a sized up by 125% because standard CBs are rated only 80%. 100% rated CBs do not require the additional 125% - even for continuous loads. The feeder cable must also be sized up by 125% to meet NEC 240. The boxes will never see more than 30A-40A of non-continuous loads due to the nature of the loads themselves. You have not convinced me the installation is unsafe. And will it not be changed. But thanks for your observations Case closed


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[texie]

I didn’t misunderstand anything. For continuous loads the CB is a sized up by 125% because standard CBs are rated only 80%. 100% rated CBs do not require the additional 125% - even for continuous loads. The feeder cable must also be sized up by 125% to meet NEC 240. The boxes will never see more than 30A-40A of non-continuous loads due to the nature of the loads themselves. You have not convinced me the installation is unsafe. And will it not be changed. But thanks for your observations Case closed


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While I admire your tenacity, I must say you are simply wrong. Your installation violates the NEC and the NRTL standards that the spider box is listed to. I will politely say that this demonstrates a lack of understanding of NEC fundamentals and NRTL standards.
But as you say, case closed, so I don't think I or anyone else here can convince you otherwise.

 

[Dale001289]

I didn’t misunderstand anything. For continuous loads the CB is a sized up by 125% because standard CBs are rated only 80%. 100% rated CBs do not require the additional 125% - even for continuous loads. The feeder cable must also be sized up by 125% to meet NEC 240. The boxes will never see more than 30A-40A of non-continuous loads due to the nature of the loads themselves. You have not convinced me the installation is unsafe. And will it not be changed. But thanks for your observations Case closed


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It’s not code complaint but most inspectors would allow it to stand given the scenario as described.


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[Dale001289]

While I admire your tenacity, I must say you are simply wrong. Your installation violates the NEC and the NRTL standards that the spider box is listed to. I will politely say that this demonstrates a lack of understanding of NEC fundamentals and NRTL standards.
But as you say, case closed, so I don't think I or anyone else here can convince you otherwise.

During the construction process, electrical superintendents have to look at the overall risk. If the code was strictly followed in every single situation construction costs would go through the roof. This installation is not unsafe.


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[texie]

During the construction process, electrical superintendents have to look at the overall risk. If the code was strictly followed in every single situation construction costs would go through the roof. This installation is not unsafe.


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I'm not saying it is unsafe or not. I'm simply saying it does not meet code which the OP in arguing it is.

 

[Tulsa Electrician]

Did I miss it some where?
What size and type of temporary cord was used.

How hard is it to put in a 50 and be done with it.

Back to op question.
To figure a base number out.
Use you cord size and distance to each load. Assign a load to each box. Then you will have an answer. Most of the time these days there nothing heavy other than radios and battery chargers. Maybe a roto hammer stud saw.
I would figure per box a load of 3kva.
This will get you close on VD.

Be sure to start with an accurate voltage reading at the source. Also keep in mind most of this will be line to netural loads.

Helpful notes for site:
So at each box label battery chargers, cord load(saw/drill)
This way you can balance loads. Then if a trip occurs you can show GC to pass along. Or he can pay to put in more.
Also limit each subs cord to 100' or it's on them. And let them know if cord is too small of gauge and there an issue with the load, it's on them.

Look forward to see what you come up with.

 

[Todd0x1]

The feeder cable to the box is sized at 65A

How are you coming to that conclusion? 6/4 SOOW cable is rated for 55 amps in 120/240v single phase (2 CCC) and 45 amps in your application -3CCC when H-H-N supplied from two phases of a 3ph system.