Wiring boilers

Ken C.

A coworker and I recently went to start up an oil-fired Buderus boiler with a Logamatic and an indirect HWH. Our company, which does mainly new construction plumbing and heating, installed the boiler, but the GC usually has his electrician wire the controls. Anyway, this electrician made several wiring mistakes that we had to correct. The sparky also didn't install the outdoor air sensor (he probably didn't know what that little white box was). Most plumbing/heating guys will wire the boilers they install, but a few would rather have an electrician do it, either for lack of time or because they simply don't like to wire. Trouble is, I've heard there is a high rate of mistakes because the average residential electrician isn't familiar with heating systems and their controls. Do you agree?

Ken_8

Absolutely Agree!

Most sparkies are good at 115 single phase, 230, 440 3phase etc. Give them Belden wire and a 5 VDC circuit and they leave town.

If I have to have them, I ask them to leave a 1900 ('J') pull or junction box overhead with a 115V hot black, a white neutral and a greenie/ground - no cover.

We take it from there.

In NJ, the only exemption for a licensed electrician to wire anything is heating and A/C guys (and the homeowner).

We are "exempt" from licensure - as long as a dedicated boiler breaker (typically 15 amp) is installed in the panel by the licensed sparky.

We run 440 3-phase - no license required. A few motors on some larger air handlers or bigass boilers will run 440 3-phase.

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DaveGateway

Agree wholeheartedly

All I require from the electricians is a dedicated circuit to the boiler area. ALL low voltage is run by us. If provided with a complete wiring diagram I'm sure they can handle it but I take as much pride in the pumps and control wiring install as the piping. Nothing toasts a nice looking installation than a bad wiring job.

Weezbo

Enlightening N'est pas?

same old tune 6.... "well, let me ask when the electrician is comming back to wire the sensor?....so i can come back and see the complete insallation","Do You Have to Come Back?" "Lady I dont Have to do Anything",turn on my heels and walk...
"oh ah umm... er...is there something wrong with it?"
I think of saying 'Yah Your Attitude!' oops."Well it was working fine when I left and had done so for months before it was put under control by the electrician, perhaps i will ask him when i see him on the next rough in..."
...So when i see him i ask well are you almost out on such and such "nah we are outta there.!"
"Oh....,Well, i stoped in to pick a few utility cords up and noticed the sensor on the tek mar injection system wasnt landed...." he Knows what i am saying is true. so hes kinda like 'ok. wellp. dog doo doo, I guess i best go check'.
there are lotsa controls.this is why we have unlimited licences ....Electricians understand the fact thier trade has become a proffession and some things require special education ....... i think i could do fiber optic lash ups and donated the first fiber optic hand book to the geophysical library in like 1980 or so. i am sure this is now a field that has distanced it self from common residential electricians or may be even Many ELectrical contractors.
There are things in our field that while i have considered many times to do, i have yet to install,it is like this in the new world:) Theres a microscope on me for a second.... I admitt it though:)

Jeff Lawrence_24

I'm with him!

I was on a job on Tuesday and told the homeowner that I would do all the wiring for my system. The sparky needs to give me a junction box with a switch in it and I'd do the rest. When the GC and the HO looked at me funny, I told them I wouldn't miswire my own system. That earned me a wise look from the HO and an embarressed look from the GC.

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Mark Eatherton1

We wire our own...

If the sparky wants to argue, then we say "OKay, then give us your home telephone number so when they call and complain that they have no heat we can have them call you and make sure its not YOUR problem..."

I've never had one that didn't relenquish their power.

We take it from the fused disconnect that they provide, and we offer them an open box inspection prior to cover.

Had one boiler than the sparky wired that ran all the time. When questions, he said "If'n ya didn't want it to run ALL the time, why'd ya have me run power to it?"

I do envy sparkies however, they understand hydronics better than most hydronics people do due to their backgrounds. Amps watts and volts = pressure, flow and flow resistance!

ME

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mph

Sparkies

Here in sunny Washington state only licensed electricians can wire line voltage. We have to have a special HVAC low-voltage license to do our side. Although we cannot do the initial pump wiring, we can later do replacements as long as we replace like-for-like.

I would never let a sparkie do my low voltage. I'd have to stand next to him to show him what to do and it still wouldn't come out looking right. (I don't use any wire nuts on my stuff). That's not to say the local sparkies couldn't learn to do it; I just don't see any of them heading off to Tekmar training classes.

Jeff

Alan(CaliforniaRadiant)Forbes

SSU

We show the electrician where to install the SSU (fused switch) with a 6¼ amp fuse and we take it from there using 14/2 MC lite cable.

Are you guys going to give me flak for using 14 ga. wire?

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Ken_8

No flak..

As long as the breaker is no more than a 15 amper...

In your case - a 6.5 D.C.

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Matt Undy

wire sizing

When motors are involved, the length of the run and size of the motor com into play also, not just the size of the overcurent protection. If the run is long enough so that its resistance is high enough that it can not provide enough voltage at the locked rotor current of the motor then the motor will burn out or trip its overload instead of starting. This is unlikely for a motor with a full load current under 6.5 A but it could be an issue on an extremely long run. Also, if it were in a raceway with enough other conductors it could be derated below 15 A. Technically 14 ga. wire can carry about 20A according to the heat dissipation calculations of the NEC depending on the tempurature rating of the insulation. There is aother rule that specifically says that 14ga wire can not be protected at over 15A.

I do have some problems with somone without some sort of traning in line voltage wiring methods wiring HVAC equipment. They don't know som of the ffiner details of the code. The contractor that instlled my furnace did the wiring and did not propperly secure the conduit and did not terminate the wiring at the switch. Instead of looping the wires around the terminal screws, he simply stuck them straight under and tightened the screws like it was 24V wiring to a Honeywell control. Some switches and other devices have terminals listed for this type of termination. This device is not. It could potentialy overheat at higher curents. It must be terminated in the maner it was tested for its listing.

He also failed to use anti short bushings in the ends of the greenfield.

It makes sense for HVAC contractors to do the control wiring, the power involved is too small to heat enough to cause a fire, but the line voltage wiring should be done bey someone with the proper licensing. I'd be happy if enough to know how to run raceway and terminate wiring were part of the HVAC licensing. HVAC equipment consumes a lot of power, is more likely to be in conditions that deteriorate electrical wiring materials and terminations, and is more likely to be used unattended than a dryer or range. It is very important that the propper materials be used and that they be installed correctly.

Matt

John Felciano

Never

Let electricians near our boilers.We have them provide us with a 115 volt switch and we take it from there.For some reason the electricians around here have no clue how to wire controls.They seldomly ever get even zone vales wired correctly and the mess of BX they leave is awefull.

Unknown

Why

no wire nuts ?

DaveGateway

Way to Chime in Matt

It's good that an electrical PRO added his two cents and sense. Wire sizing and derating are things a lot of HVAC contractors need to know. Fortunately most of our residential equipment operates at low enough current that bad connections rarely overheat. Most boiler and pump systems actually operate at less current draw than a 1200 cfm furnace. It still doesn't condone poor connection and safety practices. Allen's 6&1/4Amp SSY, while no longer required by code in most locations as primary disconnect, is not a bad idea for overload protection.

Most of us do enough research into control stategies and VA ratings of our low volt stuff, we shouldn't (and probably most don't) overlook the line volt equipment.

Has any one needed and/or requested TWO circuits for a residential installation? I'm curious. Stack up enough 1/20 hp pumps and anythings possible.

Ken C.

Speaking of bad wiring...

... the sparky on the afore-mentioned job used armored cable instead of EMT to run the 115-V circuit from the Firomatic junction box down to the boiler. Looked like a vine swaying from the ceiling.

stonehouse_2

Matt, are bushings required on Greenfield, I know it is for BX but I always thought Greenfield was exempt...never understood why though....

Matt Undy

First a disclaimer. I am not a licensed electrician but have done enough reading to install my own electrical system properly. I am also an EE. I believe my information to be correct but assume not liability if it is not correct.

I can’t see how the Greenfield connector he installed is listed for use without a bushing. The cut edge and the sharp edge of the end of the Greenfield is exposed in a way that the wiring could contact and be cut by it. I meant to take a picture of the fiting as installed. It is the 90 degree type with a sheet metal cover that clamps the Greenfield in. I think there are some fittings that screw into the end like liquidtite fittings do, these would protect the wiring and not require a bushing, just like the shoulder inside EMT fittings but without it the only way I see that the wiring would be adequately protected is with an anti-short bushing.

Incompetent electricians are another matter. BX and Greenfield must be secured every 4.5’ and near every box. There is an exception for vibration isolation and things that must move somewhat for adjustments but hanging from the ceiling is a clear violation.

As far as proper termination goes, I was thinking more AC condensers and packaged units. They along with their disconnects are out prone to dampness and seem to frequently be wired with aluminum wire.

Matt

stonehouse_2

I'm no electrician either...

nor an engineer, but I vaguely remember from my youthful reading, that Greenfield (Flexible Metal Conduit) didn't require them...though I never knew why... After a lot of Googling I found the NEMA document dealing with this.

Check out:
http://www.nema.org/DocUploads/F16833FA-FA67-4B0C-BA0ACB3B9ECCC892/FB_2_20.pdf

page 18 on the PDF or their page 10.

It seems that FMC connectors have smooth innards that are supposed to bush the "square cut" end of the FMC... It seems the reason for not using bushings is that they won't stay on when you pull the cable through. BX cable already has the cable in it, so there is generally no stress on the bushing...

Matt Undy

Ok, so sometimes i'm wrong....The square cut ends is vitaly important though. The method used to cut BX where one turn of the spiral is cut and it is "unwound" wouldn't be acceptable. Even the pretty comprehensive book I have on residential wiring doesn't mention that it must be square cut, but unless it is the shoulder doesn't offer any protection (which it wasn't in this installation). Some connectors are far better than others. I think there is a type that screws into the end of the FMC which would offer much better protection than the clamp on type. I have attached pictures of 2 styles. I would not use the first type as its shoulder isn't that robust and isnt' cintinued in the cover. I'd use the second type if I couldn't find anything better. There are many methods that are approved that aren't particularly safe such as the spring pressure type backwire devices and recepticles with contacts that loosen up within a few years of use.

Matt

joel_19

last call

One of the last calls into my office yesterday, "The electrition couldn't get the furnace and A/C going at xxx He said he thinks your unit has a defective transformer, and you need to come fix it" good timing on this thread, that's all i've got to say!

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lchmb

just an afterthought

another reason greenfield does not require a bushing is due to the cut being made with a hacksaw. I have seen a number of tech's pull out the handy dandy copper cutter and snip of a piece..problem with that is it roll's the greenfield in leaving a razor edge inside...