Portable plug in equipment

[don_resqcapt19]

I don't read it that way. I think it says (from memory) supplementary overcurrent protection AT the equipment, or something to that effect. Don't have the code with me, so I can't verify the wording.

It is not completely clear. To me the wording implies the protection on the line end of the cord.

240.10 Supplementary Overcurrent Protection.
Where supplementary overcurrent protection is used for luminaires, appliances, and other equipment or for internal circuits and components of equipment, it shall not be used as a substitute for required branch-circuit overcurrent devices or in place of the required branch-circuit protection. Supplementary overcurrent devices shall not be required to be readily accessible.

 

[don_resqcapt19]

If this were permantly installed equipment the OP could make a 10 foot 14AWG feeder tap on a 60 amp circuit and land it on the disconnect for his equipment.

The only difference in his situation is the cord and plug everything else is the same. The tap starts in the cord cap and ends in the disconnect in his equipment.

But I think that is a huge difference as far as the code rules go. I don't think you can call a cord and plug connection a feeder tap. If you could make a case that the cord and plug connection is a feeder tap, then there would be no issue here.

 

[david luchini]

It is not completely clear. To me the wording implies the protection on the line end of the cord.

Quote:
240.10 Supplementary Overcurrent Protection.
Where supplementary overcurrent protection is used for luminaires, appliances, and other equipment or for internal circuits and components of equipment, it shall not be used as a substitute for required branch-circuit overcurrent devices or in place of the required branch-circuit protection. Supplementary overcurrent devices shall not be required to be readily accessible.

Interesting, to me that wording implied an OCPD installed within, or as part of the luminaire or appliance.

I did a google search and found an interesting document about "supplementary overcurrent protection" on the UL website.
http://www.ul.com/global/documents/...cal/ul_OvercurrentProtectionSupplementary.pdf

It seems to suggest that the supplemental protection in 240.10 is internal to the appliance. It says "In contrast to Listed circuit breakers, supplementary protectors are Recognized Components. They have only been investigated for factory installation in Listed products where UL has investigated the suitability of the combination."

So I'd say the code would allow a flexible cord to have an ampacity in line with the supplementary overcurrent protection, so a 15A flexible cord could run from a 60A receptacle to a listed appliance with a 15A supplementary OCPD, but....Since this is not a Listed piece of equipment, that section would not apply in this case.

 

[kwired]

But I think that is a huge difference as far as the code rules go. I don't think you can call a cord and plug connection a feeder tap. If you could make a case that the cord and plug connection is a feeder tap, then there would be no issue here.

After some more reading I think the only thing preventing us from using a flexible cord as a feeder tap is 240.21(B)(1)(3) and 240.21(B)(2)(3). They both require physical protection of the tap conductors by a raceway or other approved means which the jacket of a flexible cord is probably out of the question. If it were not for these two sections I think you could do it.

If you install it the way the OP wants to I don't see how you can call it anything but a feeder tap, but it is not a legal feeder tap for the reasons mentioned.

OP probably needs to use a 60 amp cord. That will still be easier and less costly than changing multiple receptacles if that is what he is needing, if he only needs to plug this in at one location then a 20 amp receptacle and cord cap plus fuses/reducers are likely less than the 60 amp cord cap alone.

 

[LarryFine]

How about assembling a portable adapter, with a 60a plug and short cord, 2 or 3 15a fuses in of some sort of housing, and a 15 (or 20) amp receptacle?

 

[kwired]

How about assembling a portable adapter, with a 60a plug and short cord, 2 or 3 15a fuses in of some sort of housing, and a 15 (or 20) amp receptacle?

Would still be simpler and cost less to just use a 60 amp cord. He said he has 15 amp overcurrent device in the equipment he is connecting.

 

[dbuckley]

This is a question that coimes up all the time in entertainment technologies.

Every creditable set of regulations worldwide requires that the flexible cord must be protected from damage due to excessive current flowing.

The equipment mounted circuit breaker will ensure this under normal operating circumstances. So having a 60A socket with a 60A plug in it with a 15A rated cable to a machine protected with a 15A breaker is a safe situation; there will never be more than 15A flowing through the cable. However, not all juristictions see it this way, some allow, some do not.

The other issue is under short circuit condiitions where you cannot rely on the 15A breaker to protect the cable, the fault may occur prior to the breaker, for example, in the cable itself. Then the question becomes will the cable be (further) damaged by the shoprt circuit current that will flow until the upstream breaker opens? There are many variables involved in that question.

So in practice, if you have a threre foot cable that has an oversized plug on it and a correctly rated breaker in the thing, generally that is viewed as acceptable. A fifty foot cable wouldn't be and would require better protection.

 

[don_resqcapt19]

This is a question that coimes up all the time in entertainment technologies.

Every creditable set of regulations worldwide requires that the flexible cord must be protected from damage due to excessive current flowing.

The equipment mounted circuit breaker will ensure this under normal operating circumstances. So having a 60A socket with a 60A plug in it with a 15A rated cable to a machine protected with a 15A breaker is a safe situation; there will never be more than 15A flowing through the cable. However, not all juristictions see it this way, some allow, some do not.

The other issue is under short circuit condiitions where you cannot rely on the 15A breaker to protect the cable, the fault may occur prior to the breaker, for example, in the cable itself. Then the question becomes will the cable be (further) damaged by the shoprt circuit current that will flow until the upstream breaker opens? There are many variables involved in that question.

So in practice, if you have a threre foot cable that has an oversized plug on it and a correctly rated breaker in the thing, generally that is viewed as acceptable. A fifty foot cable wouldn't be and would require better protection.

Specifically what code section will permit the use of a 15 amp cable with a 60 amp plug and a 60 amp OCPD?

 

[dbuckley]

Specifically what code section will permit the use of a 15 amp cable with a 60 amp plug and a 60 amp OCPD?

I've no idea, and thus I've not attempted to address that issue, that's one for the code gurus to argue over. Edited to add that in a highly regulated electrical environment, such as that mandated by the NEC, there isn't generally much discussion whether something is safe or not; one discusses whether it is compliant, the question of first principle safety being ignored.

I've given a first principles discussion related to the safety (and otherwise) of such an arrangement, assuming a regulatory vacuum.

 

[kwired]

This is a question that coimes up all the time in entertainment technologies.

Every creditable set of regulations worldwide requires that the flexible cord must be protected from damage due to excessive current flowing.

The equipment mounted circuit breaker will ensure this under normal operating circumstances. So having a 60A socket with a 60A plug in it with a 15A rated cable to a machine protected with a 15A breaker is a safe situation; there will never be more than 15A flowing through the cable. However, not all juristictions see it this way, some allow, some do not.

The other issue is under short circuit condiitions where you cannot rely on the 15A breaker to protect the cable, the fault may occur prior to the breaker, for example, in the cable itself. Then the question becomes will the cable be (further) damaged by the shoprt circuit current that will flow until the upstream breaker opens? There are many variables involved in that question.

So in practice, if you have a threre foot cable that has an oversized plug on it and a correctly rated breaker in the thing, generally that is viewed as acceptable. A fifty foot cable wouldn't be and would require better protection.

I've no idea, and thus I've not attempted to address that issue, that's one for the code gurus to argue over. Edited to add that in a highly regulated electrical environment, such as that mandated by the NEC, there isn't generally much discussion whether something is safe or not; one discusses whether it is compliant, the question of first principle safety being ignored.

I've given a first principles discussion related to the safety (and otherwise) of such an arrangement, assuming a regulatory vacuum.

With that line of thinking I would say the cord needs to be at least sized to 250.122 and the 60 amp overcurrent device would be protecting a cord no smaller than 10 AWG although 240.5 does not allow that.

Like I mentioned a few posts back if this were any method beside flexible cord you can use feeder tap rules and 14AWG would be acceptable.

 

[KermodeKT]

Yes, LarryFine, That is the exact question. I cannot change the 60A fuses, as other equipment must have use of this receptical, and requires the full 60 A. My equipment needs 15A service but the receptical I have access to is 60A. I was trying to find something in the code that lets me downsize the cord. Kinda like a lamp cord plugged into a 20 amp outlet. I hope this make a little sense.

 

[Cold Fusion]

Yes, LarryFine, That is the exact question. I cannot change the 60A fuses, as other equipment must have use of this receptical, and requires the full 60 A. My equipment needs 15A service but the receptical I have access to is 60A. I was trying to find something in the code that lets me downsize the cord. Kinda like a lamp cord plugged into a 20 amp outlet. I hope this make a little sense.

Yes, sure does. The code section that applies is 90.2. What you are doing is not premises wiring any more than a table lamp or a cord and plug HomeDepot sump pump.

If cord and plug appliances were mandated to follow the posts here, the AHJ would be making house raids to insist on all 1/8hp sump pumps plugged into 20A receptacles have a #12SO cord.

A 15A cord with a 60A plug is just fine.

If you have to have a code/spec to build to, I'd recommend looking for a Ul spec on cord and plug equipment.

cf

 

[iwire]

Yes, sure does. The code section that applies is 90.2. What you are doing is not premises wiring any more than a table lamp or a cord and plug HomeDepot sump pump.

If cord and plug appliances were mandated to follow the posts here, the AHJ would be making house raids to insist on all 1/8hp sump pumps plugged into 20A receptacles have a #12SO cord.

A 15A cord with a 60A plug is just fine.

If you have to have a code/spec to build to, I'd recommend looking for a Ul spec on cord and plug equipment.

cf

I disagree, the NEC is full of requirements that apply to portable appliances and utilization equipment.

 

[KermodeKT]

I would like to thank all of you for your responses, from the excellent conversations I see this is a good question for debat. To note, I am being required to sevice my equipment with 10 AWG cord (not by code as much as the end user), I'll just have to make a step to feed it into the 15A breaker.

 

[gadfly56]

Yes, sure does. The code section that applies is 90.2. What you are doing is not premises wiring any more than a table lamp or a cord and plug HomeDepot sump pump.

If cord and plug appliances were mandated to follow the posts here, the AHJ would be making house raids to insist on all 1/8hp sump pumps plugged into 20A receptacles have a #12SO cord.

A 15A cord with a 60A plug is just fine.

If you have to have a code/spec to build to, I'd recommend looking for a Ul spec on cord and plug equipment.

cf

I won't pretend to be conversant with the finer code points discussed thus far. I have two questions and one suggestion.

Is the 60A plug going to be able to accept the conductor size of the 15A cord? Terminal connections frequently have minimum as well as maximum size requirements.

If there was a high-resistance fault prior to the 15 amp OCPD, line-to-line or line-to-ground, would the 15A cord be more likely to be the source of a fire than the 60A cord due to the likely longer trip time on the 60 amp OCPD?

All other things being equal, for a custom piece of equipment I personally can't see a significant project cost difference; I'd go with a 60A rated cord. It's going to have better survivability in an industrial setting, especially if this portable equipment is going to be hauled from pillar to post.

 

[jim dungar]

I disagree, the NEC is full of requirements that apply to portable appliances and utilization equipment.

I disagree with the concept "full of".

Yes, the NEC does have a few requirements for cord connected end use equipment (primarily appliances in 422). Except for requiring GFCIs on vending machines, it seems the NEC leaves the details of selecting the cord, size and type, to the equipment manufacturer and and applicable listing agencies.

 

[iwire]

I disagree with the concept "full of".

OK agreed, lets back it down to quite a few. But I disagree that 90.2 has the NEC stopping at the outlet.

I doubt even UL will allow a 15 amp cord on a 60 amp circuit.

 

[Cold Fusion]

OK agreed, lets back it down to quite a few. ...

How about two - vending machines and hair dryers

... But I disagree that 90.2 has the NEC stopping at the outlet. ...

There is absolutely no question that you could find an AHJ that agrees with you and is willing to make house raids to see what is being plugged into receptacles. There is a real problem with an AHJ shutting down a project just because it does "does not feel right"

But - consider this, you guys are pretty good code readers and "code understanders" and in 30 odd posts you guys can't figure out what sections apply - maybe that's because they don't (apply - that is)

... I doubt even UL will allow a 15 amp cord on a 60 amp circuit.

...All other things being equal, for a custom piece of equipment I personally can't see a significant project cost difference; I'd go with a 60A rated cord. It's going to have better survivability in an industrial setting, especially if this portable equipment is going to be hauled from pillar to post.

Gad, you're right - it likely isn't the money. The reason is no one wants to drag around a hundred feed of 4c - #6, type G or W. They would much rather drag around a 4c-#12 or 4C-#10.

edit to add:; make that a #4 if it is an SO

iwire -
If it were me building it, I'd check rather than just discount out-of-hand. That would be pretty poor engineering.

But if you don't like a #12, use a #10.

cf

 

[gadfly56]

Gad, you're right - it likely isn't the money. The reason is no one wants to drag around a hundred feed of 4c - #6, type G or W. They would much rather drag around a 4c-#12 or 4C-#10.

Well enough, but the OP was talking about 10'. I doubt that even a dedicated desk jockey like yours truly would have a problem dragging around that length of cord.