Low Voltage Transformer Wiring-Michigan

[Sarray]

Hello,

I am being told by an inspector if a low voltage lighting fixture in a store has a Class 2 transformer it must be hardwired.

Also that It must be placed in a metal enclosure, which I do not see in UL-962 & UL-65.

Typically we don't hardwire the LED lights and the transformer and we never use a metal enclosure for the transformers. We use UL-Listed Transformer without a metal enclosure which comes with a plug that directly plugs into the wall.

Could it be because this specific transformer is located in a metal enclosure and the plug is hardwired inside the metal enclosure?

Inspector is suggesting to remove the plug and attach a metal conduit which must be hardwired by an electrician at the store. I am trying to understand that why does a low voltage transformer require a metal enclosure and why is a metal conduit required for the cord plugging into the low voltage transformer. I understand if it was a quadbox or a jbox or a combination of the two but it is just a class 2 transformer rated less than 100W..

I tried to look up the code for Michigan to see if it any different but I am can't find any related information..

Can you some one please advise?

 

[iwire]

See 411.4(A) and (B)

About the transformer.

 

[hbiss]

A little more about the location of this transformer and receptacle. Anything above a ceiling? Does either the power cord or the LV wiring have to go through a hole in the wall or ceiling?

-Hal

 

[Sarray]

See 411.4(A) and (B)

About the transformer.

Thank you for the guidance.

As per 411.A the secondary end of an isolated transformer shouldn't be grounded, which is fine because we never ground the secondary (DC) side of the wiring

411.B requires an isolation transformer for low voltage lightings an automated transformer is not acceptable as primary and secondary are not isolated.


Here is my understanding of the isolated and non-isolated transformer. An Isolated transformer has a Line and Neutral on the primary side. When a 3 prong plug is attached to an isolated transformer the ground wire of that plug needs to be grounded to metal. Hence, the adapter must be placed in a metal enclosure so that ground wire from the plug can be attached to the metal.

A non-isolated transformer is all one assembly. A 3 prong plug from the receptacle directly plugs into the adapter which is already grounded therefore the adapter does not need to be placed in metal enclosure and hence no additional grounding is required.

Typically we never use the isolated transformers for our lightings which is why were never asked to "hardwire" the primary side of the transformers by any inspector. In this specific project the vendor who wired the fixture for us used a non-isolated transformer and I am suspecting that that is the reason why we are asked to hardwire the plug coming out of the low voltage transformer...

 

[Sarray]

A little more about the location of this transformer and receptacle. Anything above a ceiling? Does either the power cord or the LV wiring have to go through a hole in the wall or ceiling?

-Hal

We have a store fixture which is placed directly against the wall. The transformer is located at the top of the fixture inside an enclosure and only the transformer cables coming out of the fixture and plug into the receptacles. None of this is visible from the outside.

None of the receptacles and transformers are located above the ceiling. Power cord doesn't travel through the wall but it plugs into the wall. Low voltage lightings are only wired within the fixture for the lightings therefore they never go through the wall or the ceiling.

 

[hbiss]

Thank you for the guidance.

As per 411.A the secondary end of an isolated transformer shouldn't be grounded, which is fine because we never ground the secondary (DC) side of the wiring

411.B requires an isolation transformer for low voltage lightings an automated transformer is not acceptable as primary and secondary are not isolated...

Don't know where you got that from.

411.4 Specific Location Requirements
(A) Walls, Floors, and Ceilings. Conductors concealed or
extended through a wall, floor, or ceiling shall be in accordance
with (1) or (2):
(1) Installed using any of the wiring methods specified in
Chapter 3
(2) Installed using wiring supplied by a listed Class 2 power
source and installed in accordance with 725.130

(B) Pools, Spas, Fountains, and Similar Locations.
Lighting systems shall be installed not less than 3 m (10 ft)
horizontally from the nearest edge of the water, unless permitted
by Article 680.

We have a store fixture which is placed directly against the wall. The transformer is located at the top of the fixture inside an enclosure and only the transformer cables coming out of the fixture and plug into the receptacles. None of this is visible from the outside.

None of the receptacles and transformers are located above the ceiling. Power cord doesn't travel through the wall but it plugs into the wall. Low voltage lightings are only wired within the fixture for the lightings therefore they never go through the wall or the ceiling.

This is what I thought, it's a store fixture that is plug and cord connected. NEC is not applicable so I have no idea why the inspector is even involved. Maybe Canada is different?

-Hal

 

[K8MHZ]

This is what I thought, it's a store fixture that is plug and cord connected. NEC is not applicable so I have no idea why the inspector is even involved. Maybe Canada is different?

-Hal

OP specified Michigan. If he is having problems with an inspector making up code, he can call the state.

Contact the Electrical Division:
Phone: 517-241-9320
Fax: 517-373-8547
E-Mail: bccelec@michigan.gov
The Electrical Division is responsible for the administration and enforcement of the Michigan Electrical Code and the electrical provisions of the Michigan Residential Code by conducting inspections of electrical wiring and installations. The division also follows up on violations of the Michigan Electrical Code and assures proper electrical permits have been issued.

 

[Sarray]

Don't know where you got that from.

411.4 Specific Location Requirements
(A) Walls, Floors, and Ceilings. Conductors concealed or
extended through a wall, floor, or ceiling shall be in accordance
with (1) or (2):
(1) Installed using any of the wiring methods specified in
Chapter 3
(2) Installed using wiring supplied by a listed Class 2 power
source and installed in accordance with 725.130

(B) Pools, Spas, Fountains, and Similar Locations.
Lighting systems shall be installed not less than 3 m (10 ft)
horizontally from the nearest edge of the water, unless permitted
by Article 680.



This is what I thought, it's a store fixture that is plug and cord connected. NEC is not applicable so I have no idea why the inspector is even involved. Maybe Canada is different?

-Hal

It was a US Store inspector in Michigan who flagged the fixture

Store Inspector flagged the fixture and said that the Cable carying Line voltage to the adapter MUST be hardwired, which has never been a concern in the past.
Typically what we have done in the past is use the a low voltage lighting set up where we don't have to worry about any grounding or metal enclosures. Plug from the wall directly goes into the Adapter, out of the Adapter we have connections straight to the low voltage lightings.

In this specific case our vendor who built the units used the non-isolated low voltage transformers....These transformers are hardwired within a metal enclosure. Line Neutral from the Plug wired to Line and Neutral of the adapter and the Ground from the plug is connected to a grounding bolt attached to a metal enclosure. I am assuming due to this set up we are being asked to hardwire the AC side of the adapter?

Instead of retrofitting and hardwiring every single fixture, can simply use isolated transformers so there is no hardwiring and grounding the AC side is involved?

 

[K8MHZ]

It was a US Store inspector in Michigan who flagged the fixture

Store Inspector flagged the fixture and said that the Cable carying Line voltage to the adapter MUST be hardwired, which has never been a concern in the past.
Typically what we have done in the past is use the a low voltage lighting set up where we don't have to worry about any grounding or metal enclosures. Plug from the wall directly goes into the Adapter, out of the Adapter we have connections straight to the low voltage lightings.

In this specific case our vendor who built the units used the non-isolated low voltage transformers....These transformers are hardwired within a metal enclosure. Line Neutral from the Plug wired to Line and Neutral of the adapter and the Ground from the plug is connected to a grounding bolt attached to a metal enclosure. I am assuming due to this set up we are being asked to hardwire the AC side of the adapter?

Instead of retrofitting and hardwiring every single fixture, can simply use isolated transformers so there is no hardwiring and grounding the AC side is involved?

Cold be the OP is dealing with an inspector that does NOT work as an inspector under Michigan's AHJ. It sounds like the inspector works for the store and is enforcing company policy, not the Michigan codes or the NEC. As such, we have no idea what the company inspector will allow. I think we are dealing with more of a contract/legal issue if the store is making requirements above the codes. It's entirely possible any advice given here, based on the NEC, may also get shot down by the company inspector.

 

[Sarray]

Cold be the OP is dealing with an inspector that does NOT work as an inspector under Michigan's AHJ. It sounds like the inspector works for the store and is enforcing company policy, not the Michigan codes or the NEC. As such, we have no idea what the company inspector will allow. I think we are dealing with more of a contract/legal issue if the store is making requirements above the codes. It's entirely possible any advice given here, based on the NEC, may also get shot down by the company inspector.

Thank you for your input. It might be the case that the inspector is requesting something not related to any code

 

[K8MHZ]

Thank you for your input. It might be the case that the inspector is requesting something not related to any code

No matter what, they can't make stuff up. Even if the inspector works for the company, the only rules he can enforce are those written by the company. Before you make any further plans, try to get a copy of the company rules. Failing that, run your new plans by the inspector you are dealing with and inform him that the changes won't be made for free, and you will need a valid PO # to charge the work to.

I would still give a call to the state. It may be the store inspector is violating state law by making up rules. Get as much info as you can before buckling under to a 'store inspector'.

 

[hbiss]

Store Inspector flagged the fixture and said that the Cable carying Line voltage to the adapter MUST be hardwired

Probably doesn't want to see flexible cords on top of fixtures because of the possibility of damage. Nothing to do with grounding.

Can you run Greenfield from a plate (remove the receptacle) to a KO in the transformer housing?

-Hal

 

[Sarray]

No matter what, they can't make stuff up. Even if the inspector works for the company, the only rules he can enforce are those written by the company. Before you make any further plans, try to get a copy of the company rules. Failing that, run your new plans by the inspector you are dealing with and inform him that the changes won't be made for free, and you will need a valid PO # to charge the work to.

I would still give a call to the state. It may be the store inspector is violating state law by making up rules. Get as much info as you can before buckling under to a 'store inspector'.

Thank you so much, I have forwarded the request for the inspector to specify which code he is referring to before we decide to go any further.

If it's just a store/company policy then retrofitting for one store is not an issue but I just need to confirm that it is not a violation of any code which may have an impact on every fixture.

 

[Sarray]

Probably doesn't want to see flexible cords on top of fixtures because of the possibility of damage. Nothing to do with grounding.

Can you run Greenfield from a plate (remove the receptacle) to a KO in the transformer housing?

-Hal

We don't have a receptacle in the transformer housing. Just a metal enclosure that contains a grounding bolt a transformer (LED DRIVER) 3 prong plug cable at the primary side and 2 Conductor DC on the secondary

 

[K8MHZ]

Thank you so much, I have forwarded the request for the inspector to specify which code he is referring to before we decide to go any further.

If it's just a store/company policy then retrofitting for one store is not an issue but I just need to confirm that it is not a violation of any code which may have an impact on every fixture.

For code violation info, you will need to call the Electrical Division, I posted the numbers. There is only one set of rules in Michigan. Local jurisdictions can no longer have their own rules. As of a couple code cycles ago, everyone in the state has to play by the same rules.

FWIW, I have called the Electrical Division before on code clarification issues and found them to be very polite, friendly and helpful.

Good luck.

 

[hbiss]

We don't have a receptacle in the transformer housing. Just a metal enclosure that contains a grounding bolt a transformer (LED DRIVER) 3 prong plug cable at the primary side and 2 Conductor DC on the secondary

You would cut the "plug cable" off within the enclosure and wire nut it to some THHN that is pulled from the receptacle box location through the Greenfield. I would pull a ground also, bond the green from the line cord to the ground screw with the green from the receptacle box.

-Hal

 

[Sarray]

For code violation info, you will need to call the Electrical Division, I posted the numbers. There is only one set of rules in Michigan. Local jurisdictions can no longer have their own rules. As of a couple code cycles ago, everyone in the state has to play by the same rules.

FWIW, I have called the Electrical Division before on code clarification issues and found them to be very polite, friendly and helpful.

Good luck.

Thank you very much! At least now its clear that it was not a grounding issue. I will call the Electrical Division as you suggested.