Using MHF2224

[johnHarley]

New to forum: posted these question on a much older thread. I will be helping my son run a line ~100' from his main 400amp house panel to a 100amp square D 8 circuit sub panel at his dock storage shed. Thinking of using MHF 2224 and burying it 18" in 2"#40 conduit. Use a 90 amp breaker in main panel. questions: how hard is it to pull through 2" conduit. Is 2224 hard to bend to connect to sub panel main and main panel 90 amp breaker? Local electrician said i don't need a ground rod for sub panel as main panel is grounded Is this true? Sub panel has 8 breaker slots 4 will be used for 220v 10amp breakers to supple indivdual boat lift motors leaving 4 empty slots. Does this qualify for 6 breaker rule and not needing a main cut off at sub panel? Am i thinking clearly on this I'm not an electrician but I have done my own house wiring when we built the house 20 years ago (no problems) Any help or suggestions would b appreciated Thanks John
johnHarley is online now Report Post

Posted in someone elses thread my mistake

 

[Norcal]

Boat lifts are required to have GFCI protection.

 

[johnHarley]

Thanks, had not thought of GFI I was thinking as in a house any outlet closer than 6' required a GFI outlet. Lift motors will be 20'+ from subpanel so regardless of distance they need GFI protection? Is dependent on location of motors to water source ?

 

[pattenp]

Boat houses and boat hoist are specified in NEC 210.8(A)(8) & (C). You should also have outlets at the dock shed GFCI protected. It's just good protection.

 

[pattenp]

The grounding electrode is to handle lighting strikes. The ground wire back to the main panel is for clearing fault current for you breakers to trip and GFCI to trip. I think the ground rod(s) for the dock shed would be a good thing so if a lighting strike happens out at the dock it doesn't potentially travel back to the house. It's just another safeguard though not guaranteed. How far out on the dock is this shed from the shoreline?

 

[johnHarley]

The dock shed is about 8' from the sea wall on solid ground. Then there is 8 foot wide dock beyond the seawall; the boat house and lift will be built out from the dock

 

[Norcal]

A detached structure requires a grounding electrode, either a UFER or a ground rod & if cannot prove 25 Ohms of resistance or less a 2nd needs to be driven at least 6 feet from the first one.

 

[johnHarley]

Thanks got an ohm meter and will add a second if needed you have been very helpful

 

[johnHarley]

Question on GFIC outlet the dock motors can't be hardwired directly from the 220v breaker in the sub panel is that correct it has to go through a GFIC outlet with a 220v plug in is that correct?

 

[Norcal]

Thanks got an ohm meter and will add a second if needed you have been very helpful

It's not that simple, you need expensive testing equipment & the expertise to use it, simpler to just the second rod & be done with it.

 

[johnHarley]

It's not that simple, you need expensive testing equipment & the expertise to use it, simpler to just the second rod & be done with it.

Thanks will do

 

[pattenp]

Question on GFIC outlet the dock motors can't be hardwired directly from the 220v breaker in the sub panel is that correct it has to go through a GFIC outlet with a 220v plug in is that correct?

Be it hardwired or plug-in, being 240V you need to use a 240V GFCI breaker for the hoist motor circuit. This is something I suggest running by your local inspector.

 

[wyliesdiesels]

Thanks got an ohm meter and will add a second if needed you have been very helpful

An ohm meter is not the right equipment for that.

 

[Bert_]

New to forum: posted these question on a much older thread. I will be helping my son run a line ~100' from his main 400amp house panel to a 100amp square D 8 circuit sub panel at his dock storage shed. Thinking of using MHF 2224 and burying it 18" in 2"#40 conduit. Use a 90 amp breaker in main panel.

questions: how hard is it to pull through 2" conduit. #2 will fly though 2", especially with only a 100' run

Is 2224 hard to bend to connect to sub panel main and main panel 90 amp breaker? It is easy to work with

Local electrician said i don't need a ground rod for sub panel as main panel is grounded Is this true? Any feeder to a detached building requires ground rods and a four wire feeder

Sub panel has 8 breaker slots 4 will be used for 220v 10amp breakers to supple indivdual boat lift motors leaving 4 empty slots. Does this qualify for 6 breaker rule and not needing a main cut off at sub panel? The six handle rule does apply but I don't think you will have any spaces left. A "220V" (double pole) breaker takes up 2 spaces.

Am i thinking clearly on this I'm not an electrician but I have done my own house wiring when we built the house 20 years ago (no problems) Any help or suggestions would b appreciated Thanks John
johnHarley is online now Report Post

Posted in someone elses thread my mistake

Looks like the GFCI issues are covered so here's my take on the rest.

 

[Crazyjake8493]

2-2-2-4 will go through 2" PVC easily. I believe 1-1/4" is minimum, I ran mine 65' through 1-1/2" with no issue.

 

[Lelandwelds]

It's not that simple, you need expensive testing equipment & the expertise to use it, simpler to just the second rod & be done with it.

It is more complicated than even that. Something about multiple ground rods is no big deal. More than a single ground wire to the breaker box is a big no no.

 

[rburke65]

For a few dollars more I would be ins5alling at least a 12 circuit panel.

 

[75gmck25]

I just went through a similar job to get power to my detached garage, and have some general observations.

- A 100 amp sub-panel with a main breaker and 24 breakers wil not cost much more than a panel with 8 breakers. Its just easier overall to use the larger panel. However, you will need to isolate the ground and install a separate grounding bar, and you may have to add a larger ground lug for the 2 gauge wire.
- You can use a 90 amp breaker in the main panel, but 60 amp is cheaper and easier to find. There is no risk or code violation with using a smaller breaker on large wire.
- You need two grounds rods at the subpanel, and continuous 6 gauge solid wire connecting the ground rods to the panel. The ground rods and ground wire are readily available at any Home Depot or Lowes.
- 2-2-2-4 MHF pulls easily through 2" conduit if you use the recommended lubricant. It is four conductors that are attached every so often with tape, so try to pull it in the direction where the end of the wire and/or the tape does not catch on the lip of the conduit joints.
- You can buy 2-2-2-4 AL MHF that is dual rated so that it can be used underground and in conduit in a building.

Bruce