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Metal Inclosure To Plastic Conduit

08/24/2011 4:19 PM

Hi Guys

I have been asked to put a DC Disconnect between my solar panels and the inverter. The cable connection between the panels and the inverter is in PVC Conduit. However the DC disconnect is in a metal box. I plan to use flexible conduit from the metal box to the existing PVC conduit with a PVC watertight thingie (not sure what the name of these things is) specially designed for these flexible conduit to connect it to a box.

Hope I explained it well and the question is: is this legal?


Fuif

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#1

Re: Metal inclosure to Plastic conduit

08/24/2011 4:30 PM

The person to ask is your local AHJ (Authority Having Jurisdiction, a.k.a your inspector). Every district and even AHJ seems to have their own preferences on the use of flex conduit.

But there is no issue at all with running PVC conduit into a metal box directly, hopefully you are not going through all this rigamarole of the flex conduit just for that reason.

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#2

Re: Metal inclosure to Plastic conduit

08/24/2011 4:45 PM

If the cable is running in plastic then there can be no real problem having a metal box if it is earthed. Who cares a monkeys how the two are connected? Alterntively mount the dissconnect in a plastic box or a cardboard cereal packet for that matter.
Who asked you to put in the dissconnect? Ask them what they would like...
Del
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#3
In reply to #2

Re: Metal inclosure to Plastic conduit

08/24/2011 4:54 PM

Del you are a baaaad kitty.
You know we need lots of inspectors to stop naughty people installing electrical switchgear in cereal packets. It should be in a Tupperwarebox at least.
Mr K Squirrel
(Safety Ocifer for KrisDelTM)

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#18
In reply to #3

Re: Metal inclosure to Plastic conduit

08/27/2011 7:50 PM

This may be updated later - disconection ? yer avin' a larf ! The East Cliff lift in Hastings got screwed yesterday. More Firecrew than I have seen in the past 20 years, and yet after 2 hours the bugger was still stuck. By stroke of luck, I was armed with zoom lens - there was one poor old dear with her face pressed to the glass like something out of a 'toon. That one ain't getting published out of respect/privacy. No idea (yet) as to the reasons the lift got stuck, but with a 1:3 gradient it must have been pretty hard for the rescue teams to rig gear.

Very Brit - major drama over a stuck lift, just as America is geting hit by a beast of a hurricane. It is, as the saying goes, a world apart.

Initial impressioins I get(been off the loop for a few days) are that contingency plans are being made. Hope to heck all are OK.

Much as I'd like to play and jest here, I'm going nuts trying to catch up on news, especially current events stateside.

**** will happen, but hopefully we can all continue to swap news and banter during hard times. From the little I have caught up on so far, it looks so be potentialy very bad. Hopefully CR4 will be one avenue for people to spread news.

K.S.

KrisDel™ may sell some top notch tat, but we also endevour to help people communicate.

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#4

Re: Metal inclosure to Plastic conduit

08/24/2011 5:00 PM

Liquid tite. Below is one of many styles. I think it would meet code, but check with local authorities as has been suggested.

Don't mind the cat. He must have a fur ball.

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#6
In reply to #4

Re: Metal inclosure to Plastic conduit

08/24/2011 5:55 PM

I was assuming the conduit and box are indoors... in which case surely a simple grommet will do the job and prevent chaffing of the cable.
I don't see why it needs to be watertight. I fact I don't really see why it needs to be in conduit. After all we have power lines strung all over the countryside and in Italy they are draped all over the buildings too without the extra protection of a plastic conduit...mind they don't build their house out of timber.
I don't think the electricity will spill out over the floor...
Del
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#9
In reply to #6

Re: Metal inclosure to Plastic conduit

08/24/2011 6:34 PM

"I was assuming the conduit and box are indoors...", and I was assuming they were outside. Otherwise, why would you need liquid tite connections?

I agree with you, indoors, it's a waste of money.

Cheers.

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#10
In reply to #9

Re: Metal inclosure to Plastic conduit

08/24/2011 6:50 PM

But it looks cool and if you spend more it's better...right?

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#15
In reply to #9

Re: Metal inclosure to Plastic conduit

08/25/2011 2:44 AM

Yup, this shows the importance of posting concise questions.
Presumably this dissconnecccttt is for the emergency services (fire brigade?) so they don't get zapped when they come to rescue any cats trapped in the building?
Del

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#17
In reply to #15

Re: Metal inclosure to Plastic conduit

08/25/2011 10:49 AM

Yes, it is for emergency responders, a.k.a. the "Cat Removal Brigade", so they can avoid getting killed by the DC power from the PV arrays as they hack through the roof with their Cat Axes to get at the errant felines. It's either that, or you have to install a remote control switch on the sun.

Of course if all cats were locked up behind bars, there would be n reason for the CRB to be going up on roofs and the problem would be solved in an indirect manner. I'm just saying...

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#5

Re: Metal enclosure to Plastic conduit

08/24/2011 5:06 PM

"(not sure what the name of these things is)" - the word you're groping for is "adapter", or possibly "gland" (though the latter is more usually used to describe a cable entry for an individual round cable).

Legal pretty much everywhere - but check your local regs.

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#7

Re: Metal inclosure to Plastic conduit

08/24/2011 6:17 PM

Hi Guys

Thanks for your answers,

The local AHJ (Authority Having Jurisdiction, a.k.a your inspector) is a government person. Try communicating with that...... impossible.

and indeed the setup is outside.

J

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#8
In reply to #7

Re: Metal inclosure to Plastic conduit

08/24/2011 6:24 PM

Hey now, somebody has to keep you cereal-box types straight!

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#11
In reply to #7

Re: Metal inclosure to Plastic conduit

08/24/2011 6:53 PM

Try to find out what IP rating you need, and select adapters accordingly.

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#12
In reply to #11

Re: Metal inclosure to Plastic conduit

08/24/2011 7:10 PM

Ok can you point me to how I find that out. THANKS

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#14
In reply to #11

Re: Metal inclosure to Plastic conduit

08/24/2011 7:51 PM

We don't use IP ratings here. Maybe we should, but most US based electricians will not know what that means.

We use NEMA ratings. If it is outdoors, it must be NEMA 3R or 4 (or 4X). Most commercial components like that will be NEMA 3R, nobody wants to spend the money for NEMA 4.

There is no exact correlation to NEMA 3R and an IP rating, but IP53 is pretty close. NEMA 3R however does not technically prevent water from entering an enclosure, just from building up to where it comes in contact with live components.

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#13

Re: Metal Inclosure To Plastic Conduit

08/24/2011 7:42 PM

This link has some information for "National" Electric Code.

  • Receptacles and switches mounted outdoors should be installed in weatherproof electrical boxes that incorporate weatherproof covers. It is advised to use bubble covers over receptacles that cover cords from the weather while they are plugged in.
    • Type UF cable is to be used for direct burial wiring needs and is identified by its grey covering. Open wiring not protected in conduit should be buried at least 24" below the surface.
    • Underground wiring run in plastic conduit must be buried at least 18" below the surface and in schedule 80 PVC. This is a more durable plastic conduit (grey colored) than its silimilar-looking water pipe that is a white or cream-colored piping.
    • Receptacle boxes that are run out into the middle of a yard or where there is no anchoring point for the junction box, must have the schedule 80 PVC embedded in concrete to supprot the box. Another method, is to attach the box to a post that is either driven or buried in the ground. Receptacle boxes should be mounted at least 12" above grade but no more than 18" above grade for the unattached method.
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#16

Re: Metal Inclosure To Plastic Conduit

08/25/2011 5:37 AM

All metal parts must be electrically connected to each other and attached to the "Grounding Electrode". This is known as "Bonding". A lug to the box and an appropriatly sized wire to the inverter panel should solve the problem.

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