Tim163
Member
- Location
- Coldwater,MI
I have driven ground rods at machines in the past as a contractor, I have driven ground rods in the past as a journeyman. I have recently acquired my masters licence, and it has come up yet again. in the past it has been one or two , and I did not say much. but this time my boss ( a mechanical engineer ) found in the nfpa 86( 86 5.2.15 "The metal frames of furnaces shall be electricallygrounded"). we have around 150 furnaces he has purchased ground rods and wire for.
my question is. dose anyone know the reason for this grounding? is it a redundant requirement that is already covered under equipment ground?
I have tried to look up the definition of "electrically grounded" in the nfpa. there is no definition that I can find.
after thinking about it for a wile, we are on a delta / delta system ( ungrounded) no neutral, 4800v primary, 480v secondary. we don't have a grounded conductor to attach it too. we are using EMT / buss duct / IMC / switchgear so the ungrounded system requirements are meet per the NEC.
I tried to explain to him that these ground rods are not away to satisfy the " electrically grounded " requirement, these ground rods are not doing any more than the 1 inch bolts in concrete holding down the furnaces, or more that the 3/4 EMT that is attached with lock nuts are already giving you. He replied with a ground is a ground. and these ground rods make it safe so no one gets shocked. I really don't know where to start, I am thinking of hooking up a 120v hot wire to a ground rod, and watching it not blow the breaker ( I digress )
he left me today with, if you can find what is required in an official document, I will not have your crew install them.
as I said earlier, I have recently got my promotion as plant Master Electrician, and I have 1 masters, 2 journeyman and 3 apprentices all asking me to get them out of this un-needed work, I would like to help them out,and open my bosses eyes to what a ground is for, and what a ground is.
Thank you all for your help and insights, I have been a Mike Holt fan since 1996 ( when I started my apprenticeship)
my question is. dose anyone know the reason for this grounding? is it a redundant requirement that is already covered under equipment ground?
I have tried to look up the definition of "electrically grounded" in the nfpa. there is no definition that I can find.
after thinking about it for a wile, we are on a delta / delta system ( ungrounded) no neutral, 4800v primary, 480v secondary. we don't have a grounded conductor to attach it too. we are using EMT / buss duct / IMC / switchgear so the ungrounded system requirements are meet per the NEC.
I tried to explain to him that these ground rods are not away to satisfy the " electrically grounded " requirement, these ground rods are not doing any more than the 1 inch bolts in concrete holding down the furnaces, or more that the 3/4 EMT that is attached with lock nuts are already giving you. He replied with a ground is a ground. and these ground rods make it safe so no one gets shocked. I really don't know where to start, I am thinking of hooking up a 120v hot wire to a ground rod, and watching it not blow the breaker ( I digress )
he left me today with, if you can find what is required in an official document, I will not have your crew install them.
as I said earlier, I have recently got my promotion as plant Master Electrician, and I have 1 masters, 2 journeyman and 3 apprentices all asking me to get them out of this un-needed work, I would like to help them out,and open my bosses eyes to what a ground is for, and what a ground is.
Thank you all for your help and insights, I have been a Mike Holt fan since 1996 ( when I started my apprenticeship)