As a marine electrician I am not licensed nor required to follow the NEC. Most mid-sized 40'-60' vessels are built to ABYC recommended standards with no legal requirement to do so. Many ABYC standards are derived from the NEC, and thus is the case for ampacity rating of portable shore power cords. These boats typically use a 50' 6/4 STOW or SEOOW cord with 120/240 50A plug and conn, and are plugged into 50a dock outlets. I feel that there would be a negligible loss in performance, but a considerable gain in portability if these cords were 8/4. It seems that the conservative ratings of table 400.5 do not reflect the advancement in portable cords, namely temp rating - now at 105C. Is my logic flawed or can I build and offer these cords to my customers, who could I get in trouble with? Thanks Gregg.
NEC 400.5 (B)
- Thread starter seatech
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Re: NEC 400.5 (B)
The problem with you suggestion is that while the cord may have a 105C rating, the equipment that it is connected to does not. In table 310.16 conductors are listed at 90C but this rating can not be used because the equipment has a max 75C rating.
The problem with you suggestion is that while the cord may have a 105C rating, the equipment that it is connected to does not. In table 310.16 conductors are listed at 90C but this rating can not be used because the equipment has a max 75C rating.
- Location
- Windsor, CO NEC: 2023
- Occupation
- Hospital Master Electrician
Re: NEC 400.5 (B)
What is the connected load on the cord in amps?
What is the connected load on the cord in amps?
pierre
Senior Member
- Location
- Westchester County, New York
Re: NEC 400.5 (B)
Just a guess - but the cords you are constructing may be fine, but who has tested them to see if they are designed to the standards that are required?
Cords are permitted to be repaired, 400.9. As far as making extension cords, that may be another issue. There are standards that manufacturers are required to follow to provide a listing/label on their cords, and you want to change the size of the conductor....HMMMM!!!!
Pierre
Just a guess - but the cords you are constructing may be fine, but who has tested them to see if they are designed to the standards that are required?
Cords are permitted to be repaired, 400.9. As far as making extension cords, that may be another issue. There are standards that manufacturers are required to follow to provide a listing/label on their cords, and you want to change the size of the conductor....HMMMM!!!!
Pierre
Re: NEC 400.5 (B)
Thanks for the posts. George, the load can be anywhere from 0-50a but on avg 20-40a is common. The cord is feeding the vessel's main panel, and its loads will determine. I can break this question down to 2 parts. Do you feel as I do, that this cable is capable of 50a without failure, and if so how can I make it compliant or do I even need to. If I need to, will it even be possible given 400.5; if I build and submit this cord to UL will they simply look at 400.5 and reject it or could it be tested and found to be capable of a 50a rating. Thanks Gregg
Thanks for the posts. George, the load can be anywhere from 0-50a but on avg 20-40a is common. The cord is feeding the vessel's main panel, and its loads will determine. I can break this question down to 2 parts. Do you feel as I do, that this cable is capable of 50a without failure, and if so how can I make it compliant or do I even need to. If I need to, will it even be possible given 400.5; if I build and submit this cord to UL will they simply look at 400.5 and reject it or could it be tested and found to be capable of a 50a rating. Thanks Gregg
- Location
- Windsor, CO NEC: 2023
- Occupation
- Hospital Master Electrician
Re: NEC 400.5 (B)
Well, something odd has already taken place, because the 50 amp OCPD's are feeding 45 amp-rated cords. Looks like from 555.19(A)(4), there is no requirement for having a 50 amp receptacle available, you could lower your OCPD to 40, then your cord would be 5 amps shy of where it should be again. There seems to be some sort of acceptance there.
I'm guessing that you don't want to do that. I think you're stuck. But then again, I've seen the Pacific ocean three times and the Atlantic once, so I haven't played with a lot of marinas!
Well, something odd has already taken place, because the 50 amp OCPD's are feeding 45 amp-rated cords. Looks like from 555.19(A)(4), there is no requirement for having a 50 amp receptacle available, you could lower your OCPD to 40, then your cord would be 5 amps shy of where it should be again. There seems to be some sort of acceptance there.
I'm guessing that you don't want to do that. I think you're stuck. But then again, I've seen the Pacific ocean three times and the Atlantic once, so I haven't played with a lot of marinas!
- Location
- Massachusetts
Seatech, Bob nailed this right off the bat.
The plug on the end of the cord will be 75 C rated at best.
If you connect a cord to this plug based on a the higher temp rating of the cord you are likely to have a plug/outlet failure.
The plug on the end of the cord will be 75 C rated at best.
If you connect a cord to this plug based on a the higher temp rating of the cord you are likely to have a plug/outlet failure.
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
Now that you have our "opinions", you should purchase the UL Standard(s) that cords are supposed to be manufactured to and you will most likely have your answer. Providing unlisted equipment will surely get your "name up in lights", maybe not the way you would like.
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