Fusible disconnect switch Requires to be locked?

al hildenbrand

Senior Member
Electrical Contractor, Electrical Consultant, Electrical Engineer
Dose a fusible disconnect switch requires to be locked? as it has no dead front and has live parts. I say yes but I am getting kick back from the Solar company's
I think you should get kick back on the "no-dead-front" rational of this. A fused safety switch is manufactured without a dead front, most of the time. And has been, and still is, a UL listed assembly all the way back to the beginning of the 1900s. The fuses are intended to be serviceable by their very nature.

A couple years ago, I had a client that was selling his large single family home, built in 1949, that had a jurisdiction based "truth-in-sale-of-housing" inspection that judged all of the fused safety switches as hazardous for lack of dead front, and that the 30 - odd switches in this sprawling, well-wired and well-maintained electrical assembly had to be repaired or replaced. The Electrical AHJ ruled that the fused safety switches, un-altered and as manufactured, were installed to the NEC of their time of installation, and were unremarkable, needing no attention. The jurisdiction housing inspectors were realized to be creating their own new code and they subsequently stopped condemning fused safety switches.


Senior Member
Clinton, WA
Inspector Peter, it sounds like you have answered your own question. If the code explicitly states that enclosures must be locked if over 1000V, then that clearly implies that enclosures are not required to be locked if under 1000V.
Yes, that’s what this forum is for, but from what I have learnt in here is that in 2020 it will be a requirement. Thank you all for your input.
Just note that that is only for PV systems. I agree with JB it doesn't make sense to require for PV but not other things - not sure what their reasoning is there. Also, those utility type locks would meet the requirement.


Senior Member
There is a change that addresses this in the 2020 code.

690.13 (A) Location. The PV system disconnecting means shall be installed at a readily accessible location. Where disconnecting
means of systems above 30 V are readily accessible to unqualified persons, any enclosure door or hinged cover that exposes live parts when open shall be locked or require a tool to open

I don't think that there is anything in the 2017 and earlier codes that would require this.

I think change is talking about DC disconnect only not AC PV disconnect especially those supplied by line side of building service main disconnect?

Anyways This is exactly same situation I am in. However I am in NEC 2014 and AHJ is considering to make local amendment as stated in NEC 2020 because it would take much longer to adopt NEC 2020 by that time NEC 2026 come out. However if the local change is adopted would it violate any NEC 2014 code?
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