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kherr
Premium Member
join:2000-09-04
Collinsville, IL

kherr

Premium Member

Grounding multiple panels

When you have multiple panels, do you connect all the ground rods together or do you leave them separate?? One panel is in a detached garage about 40’ from the house (wire length is 100’, 100A), and two are in the basement. The panel that comes off the meter only has main breakers going to subpanels (3, 2-100, 1-60). Right now only the two 100A panels are energized.

garys_2k
Premium Member
join:2004-05-07
Farmington, MI

garys_2k

Premium Member

All the grounds have to be bonded together to prevent fatal differences in voltage in the event of a nearby lightning strike. Bonding them will also improve their performance by lowering the total impedance to the ground for each connection.
kherr
Premium Member
join:2000-09-04
Collinsville, IL

kherr

Premium Member

I sorta thought that. Thanks for confirming it.

alkizmo
join:2007-06-25
Pierrefonds, QC

alkizmo to kherr

Member

to kherr
How many service drops do you have? Or is it multiple SUB panels all enegrized from one main panel? If thy are subs, then they should already be grounded to the main panel through wiring feeding them.

As for the rods, all bonded by meeting up at a central point, like in the main panel, or right next to it, I guess.
kherr
Premium Member
join:2000-09-04
Collinsville, IL

kherr to garys_2k

Premium Member

to garys_2k
Would running a #6 from the garage panel suffice or should I go #4??
kherr

kherr to alkizmo

Premium Member

to alkizmo
They're all fed from one main panel.

garys_2k
Premium Member
join:2004-05-07
Farmington, MI

garys_2k to kherr

Premium Member

to kherr
said by kherr:

Would running a #6 from the garage panel suffice or should I go #4??

I'll let the pros answer as to wire size, length may play a role, but if this is going to be trenched I'd use bare a stranded conductor to maximize contact with the soil.

nunya
LXI 483
MVM
join:2000-12-23
O Fallon, MO
·Charter

1 recommendation

nunya to kherr

MVM

to kherr
The main panel will be the main grounding / bonding point for all the other panels.
The outbuilding panel should also be 4-wire and have a ground rod.
If it was installed back when 3 wire was acceptable, a ground rod must be driven anyway and the n+g bonded. This is only allowed provided there are no continuous metallic pathways between the garage and house (conduit, gas pipe, water pipe, etc...).

All sub panels should be 4-wire back to the main panel. Hot, Hot, Neutral (isolated), Ground.

Any supplemental rods must be bonded to the main by #6 copper minimum.